Thomas Loren Friedman (; born July 20, 1953) is an American political commentator and author. He is a three-time Pulitzer Prize winner who is a weekly columnist for The New York Times. He has written extensively on foreign affairs, global trade, the Middle East, globalization, and environmental issues.

Early life and education

Friedman was born on July 20, 1953, in Minneapolis, Minnesota, the son of Margaret Blanche (née Phillips) and Harold Abe Friedman. Harold, who was vice president of a ball bearing company, United Bearing, died of a heart attack in 1973 when Tom was nineteen years old. Margaret, who served in the United States Navy during World War II and studied Home Economics at the University of Wisconsin, was a homemaker and a part-time bookkeeper. Margaret was also a Senior Life Master duplicate bridge player, and died in 2008. Friedman has two older sisters, Shelly and Jane.

From an early age, Friedman, whose father often took him to the golf course for a round after work, wanted to be a professional golfer. He played a lot of sports, and became serious about tennis and golf. He caddied at a local country club and in 1970 caddied for professional golfer Chi Chi Rodriguez when the US Open came to town.

Friedman is Jewish. He attended Hebrew school five days a week until his Bar Mitzvah, then St. Louis Park High School, where he wrote articles for his school's newspaper. He became enamored with Israel after a visit there in December 1968, and he spent all three of his high school summers living on Kibbutz HaHotrim, near Haifa. He has characterized his high school years as "one big celebration of Israel's victory in the Six-Day War."

Friedman studied at the University of Minnesota for two years, but later transferred to Brandeis University and graduated summa cum laude in 1975 with a degree in Mediterranean studies. Friedman also pursued Arabic studies at The American University in Cairo, where he graduated in 1974 from its Arabic language unit (ALU). Friedman later taught a class in economics at Brandeis in 2006, and was a commencement speaker there in 2007.

After graduating from Brandeis, he attended St Antony's College at the University of Oxford as a Marshall Scholar, earning an M.Phil. in Middle Eastern studies.

Journalism career

Friedman joined the London bureau of United Press International after completing his master's degree. He was dispatched a year later to Beirut, where he lived from June 1979 to May 1981 while covering the Lebanon Civil War. He was hired by The New York Times as a reporter in 1981 and re-dispatched to Beirut at the start of the 1982 Israeli invasion of Lebanon. His coverage of the war, particularly the Sabra and Shatila massacre, won him the Pulitzer Prize for International Reporting (shared with Loren Jenkins of The Washington Post). Alongside David K. Shipler he also won the George Polk Award for foreign reporting.

In June 1984, Friedman was transferred to Jerusalem, where he served as the New York Times Jerusalem Bureau Chief until February 1988. That year he received a second Pulitzer Prize for International Reporting, which cited his coverage of the First Palestinian Intifada. He wrote a book, From Beirut to Jerusalem, describing his experiences in the Middle East, which won the 1989 U.S. National Book Award for Nonfiction.

Friedman covered Secretary of State James Baker during the administration of President George H. W. Bush. Following the election of Bill Clinton in 1992, Friedman became the White House correspondent for the New York Times. In 1994, he began to write more about foreign policy and economics, and moved to the op-ed page of The New York Times the following year as a foreign affairs columnist. In 2002, Friedman won the Pulitzer Prize for Commentary for his "clarity of vision, based on extensive reporting, in commenting on the worldwide impact of the terrorist threat."

In February 2002, Friedman met Saudi Crown Prince Abdullah and encouraged him to make a comprehensive attempt to end the Arab–Israeli conflict by normalizing Arab relations with Israel in exchange for the return of refugees alongside an end to the Israel territorial occupations. Abdullah proposed the Arab Peace Initiative at the Beirut Summit that March, which Friedman has since strongly supported.

Friedman received the 2004 Overseas Press Club Award for lifetime achievement and the same year was named to the Order of the British Empire by Queen Elizabeth II.

In May 2011, The New York Times reported that President Barack Obama "has sounded out" Friedman concerning Middle East issues.

Views
Friedman has been criticized for his staunch advocacy of the Iraq War and unregulated trade and his early support of Saudi Royal Prince Mohammed bin Salman.

Aadhaar
Friedman has publicly expressed his support for the biometrics based Unique Identification program of India. When asked about the privacy concerns raised by the UID program in India he said

Globalization

Friedman first discussed his views on globalization in the book The Lexus and the Olive Tree (1999). In 2004, visits to Bangalore, India, and Dalian, China, led Friedman to write a follow-up analysis, The World Is Flat (2005). The book was on the New York Times Best Seller list from its April 2005 publication until May 2007.

Friedman believes that individual countries must sacrifice some degree of economic sovereignty to global institutions (such as capital markets and multinational corporations), a situation he has termed the "golden straitjacket".

In 2000, Friedman championed Free Trade with The People's Republic of China, claiming that Free Trade would make China more democratic.

He has also expressed concern about the United States' lack of energy independence. He has stated, "First rule of oil—addicts never tell the truth to their pushers. We are the addicts, the oil producers are the pushers—we've never had an honest conversation with the Saudis."

In 2007, Friedman viewed American immigration laws as too restrictive and damaging to U.S. economic output: "It is pure idiocy that Congress will not open our borders—as wide as possible—to attract and keep the world's first-round intellectual draft choices in an age when everyone increasingly has the same innovation tools and the key differentiator is human talent."

After visiting the San Ysidro Port of Entry in San Diego, California in early April 2019, Friedman wrote, "The whole day left me more certain than ever that we have a real immigration crisis and that the solution is a high wall with a big gate — but a smart gate."

Terrorism
After the September 11 attacks in 2001, Friedman's writing focused more on the threat of terrorism and the Middle East. He was awarded the 2002 Pulitzer Prize for Commentary "for his clarity of vision, based on extensive reporting, in commenting on the worldwide impact of the terrorist threat". These columns were collected and published in the book Longitudes and Attitudes. For a while, his reporting on post-9/11 topics led him to diverge from his prior interests in technological advances and globalization, until he began to research The World Is Flat.

After the 7/7 London bombings, Friedman called for the U.S. State Department to "shine a spotlight on hate speech wherever it appears", and to create a quarterly "War of Ideas Report, which would focus on those religious leaders and writers who are inciting violence against others". Friedman said the governmental speech-monitoring should go beyond those who actually advocate violence, and include also those whom former State Department spokesperson Jamie Rubin calls "excuse makers". In his July 22 column, Friedman wrote against the "excuses" made by terrorists or apologists who blame their actions on third-party influences or pressures. "After every major terrorist incident, the excuse makers come out to tell us ... why the terrorists acted. These excuse makers are just one notch less despicable than the terrorists and also deserve to be exposed. When you live in an open society like London, where anyone with a grievance can publish an article, run for office or start a political movement, the notion that blowing up a busload of innocent civilians in response to Iraq is somehow "understandable" is outrageous. "It erases the distinction between legitimate dissent and terrorism" Mr. Rubin said, "and an open society needs to maintain a clear wall between them." As part of their response to this column, the editors at FAIR encouraged their readers to contact Friedman and inform him that "opponents of the Iraq War do not deserve to be on a government blacklist-even if they oppose the war because they believe it encourages terrorism".

Kosovo War
During the 1999 NATO bombing of Yugoslavia, Friedman wrote the following in The New York Times on April 23, 1999: "Like it or not, we are at war with the Serbian nation (the Serbs certainly think so), and the stakes have to be very clear: Every week you ravage Kosovo is another decade we will set your country back by pulverizing you. You want 1950? We can do 1950. You want 1389? We can do 1389 too." Friedman urged the US to destroy "in Belgrade: every power grid, water pipe, bridge [and] road", annex Albania and Macedonia as "U.S. protectorates", "occupy the Balkans for years,"  and "[g]ive war a chance."

Fairness and Accuracy in Reporting (FAIR) labeled Friedman's remarks "war-mongering" and "crude race-hatred and war-crime agitation". Steve Chapman, critical of the response taken by NATO, referred to Friedman as "the most fervent supporter of the air war" and ironically asked in the Chicago Tribune: "Why stop at 1389? Why not revive the idea, proposed but never adopted in Vietnam, of bombing the enemy all the way back to the Stone Age?" Norman Solomon asserted in 2007 that "a tone of sadism could be discerned" in Friedman's article.

Iraq
Friedman supported the 2003 invasion of Iraq, writing that the establishment of a democratic state in the Middle East would force other countries in the region to liberalize and modernize. In his February 9, 2003, column for The Wall Street Journal, Friedman also pointed to the lack of compliance with the United Nations Security Council Resolution regarding Iraq's weapons of mass destruction:

Nevertheless, he found the incoherence of the American position to be an asset, arguing that "the axis-of-evil idea isn't thought through -- but that's what I like about it. (...) There is a lot about the Bush team's foreign policy I don't like, but their willingness to restore our deterrence, and to be as crazy as some of our enemies, is one thing they have right. It is the only way we're going to get our turkey back.

After the invasion, Friedman expressed alarm over the post-invasion conduct of the war by the George W. Bush administration. Nevertheless, until his piece dated August 4, 2006 (see below), his columns remained hopeful to the possibility of a positive conclusion to the Iraq conflict (although his optimism appeared to steadily diminish as the conflict continued). Friedman chided George W. Bush and Tony Blair for "hyping" the evidence, and stated plainly that converting Iraq to democracy "would be a huge undertaking, though, and maybe impossible, given Iraq's fractious history". In January 2004, he participated in a forum on Slate called "Liberal Hawks Reconsider the Iraq War", in which he dismisses the justification for war based on Iraq's lack of compliance with the U.N. Resolutions:

In his September 29, 2005, column in The New York Times, Friedman entertained the idea of supporting the Kurds and Shias in a civil war against the Sunnis: "If they [the Sunnis] won't come around, we should arm the Shiites and Kurds and leave the Sunnis of Iraq to reap the wind."

Critics of Friedman's position on the Iraq War have noted his recurrent assertion that "the next six months" will prove critical in determining the outcome of the conflict. A May 2006 study by Fairness and Accuracy in Reporting cited 14 examples of Friedman's declaring the next "few months" or "six months" as a decisive or critical period, dating from in November 2003, describing it as "a long series of similar do-or-die dates that never seem to get any closer".

The blogger Atrios coined the neologism "Friedman Unit" to refer to this unit of time in relation to Iraq, noting its use as a supposedly critical window of opportunity.

In a live television interview aired June 11, 2006, on CNN, Howard Kurtz asked Friedman about the concept: "Now, I want to understand how a columnist's mind works when you take positions, because you were chided recently for writing several times in different occasions 'the next six months are crucial in Iraq.'"  Friedman responded: "The fact is that the outcome there is unclear, and I reflected that in my column. And I will continue to reflect."  Responding to prodding from Stephen Colbert, Friedman said in 2007: "We've run out of six months. It's really time to set a deadline."

Environment
Iran's Great Weakness May Be Its Oil, by Thomas Friedman, challenges and debates conflicts about oil. Friedman states,"The best tool we have for curbing Iran's influence is not containment or engagement, but getting the price of oil down in the long term with conservation and an alternative-energy strategy. Let's exploit Iran's oil addiction by ending ours".

In Hot, Flat, and Crowded, he says that "any car company that gets taxpayer money must demonstrate a plan for transforming every vehicle in its fleet to a hybrid-electric engine with flex-fuel capability, so its entire fleet can also run on next generation cellulosic ethanol".

In a Fresh Dialogues interview, Friedman described his motivations for writing the book: "My concern is about America.... Demand for clean energy, clean fuel and energy efficiency is clearly going to explode; it's going to be the next great global industry. I know that as sure as I know that I'm sitting here at De Anza College talking to you. By being big in the next big thing, we'll be seen by the rest of the world as working on the most important problem in the world."

Some of Friedman's environmental critics question his support of still-undeveloped coal pollution mitigation technology ("clean coal") and coal mining as emblematic of Friedman's less than "green" commitment to renewable energy.

Israel
Friedman has been criticized by organizations such as Fairness and Accuracy in Reporting for defending Israeli airstrikes in Lebanon as a form of "educating" Israel's opponents; according to FAIR, Friedman was explicitly endorsing terrorism by Israel against Lebanese and Palestinians. Journalist Glenn Greenwald and professor Noam Chomsky also accused Friedman of endorsing and encouraging terrorism by Israeli forces.

Political reporter Belen Fernandez heavily critiques Friedman's commentary regarding Israel. Among other criticisms, Fernandez singles out Friedman's suggestion that Israeli forces were unaware that their allied Lebanese militias carried out the Sabra and Shatila massacre while under their guard, contradicting the assessments of other journalists and observers; his encouragement of strong-armed force by the Israeli army against Palestinians; and his opposition to settlements only on the grounds that they are counter-productive, rather than because they violate international law or cause suffering for Palestinians. Fernandez suggests that Friedman is most worried about successfully maintaining Israel's Jewish ethnocracy and actively opposing a "one-man, one-vote" system of democracy.

Friedman has also come under criticism from supporters of Israel. In an op-ed, Yitzhak Benhorin criticized Friedman's alleged suggestion that Israel relinquish territory it had occupied in the 1967 Middle Eastern War.

Friedman sparked criticism for writing that congressional ovations for Israeli Prime Minister Benjamin Netanyahu were "bought and paid for by the Israel lobby." A letter from the American Jewish Committee objected that "Public opinion polls consistently show a high level of American ... support for and identification with Israel. This indicates that the people's elected representatives are fully reflecting the will of the voters." Friedman responded to criticism by writing: "In retrospect I probably should have used a more precise term like 'engineered' by the Israel lobby – a term that does not suggest grand conspiracy theories that I don't subscribe to."

Friedman hailed the Trump-brokered peace agreement between Israel and the United Arab Emirates as "exactly what Trump said it was in his tweet: a 'HUGE breakthrough.

Following the outbreak of the 2023 Israel–Hamas war, Friedman urged Israel against military over-reach and futher settlement expansions, saying to do so otherwise would risk destablizing the region and the US-Israel alliance.

China
In September 2009, Friedman wrote an article praising China's one-party autocracy, saying that China's leaders are "boosting gasoline prices" and "overtaking us in electric cars, solar power, energy efficiency, batteries, nuclear power and wind power." The article was in turn subject to critical analysis: Matt Lewis who wrote, "Friedman's apparent wish for a 'benign' dictator is utopian, inasmuch as it ignores Lord Acton's warning that 'absolute power corrupts absolutely.'" and William Easterly who quotes Friedman's one-party autocracy assertions as part of his academic paper in which he concluded that, "Formal theory and evidence provides little or no basis on which to believe the benevolent autocrat story" and that, "economists should retain their traditional skepticism for stories that have little good theory or empirics to support them." However, in a July 2012 article in the NYT, he also wrote that the current Chinese leadership has not used its surging economic growth to also introduce gradual political reform and that, "Corruption is as bad as ever, institutionalized transparency and rule of law remain weak and consensual politics nonexistent." When asked if he had "China envy" during a Fresh Dialogues interview, Friedman replied, "You detect the envy of someone who wants his own government to act democratically with the same effectiveness that China can do autocratically." Likewise, in a 2011 interview with the BBC Friedman says that he wants his children to live in a world where "there's a strong America counterbalancing a strong and thriving China, and not one where you have a strong and rising China and an America that is uncertain, weak and unable to project power economically and militarily it historically did."

Friedman's work is popular in China. His book The World is Flat was a bestseller in the country, although criticism of China in the book was removed when it was published in the country. A translated version of his article from The New York Times, "China Needs Its Own Dream", has been credited with popularizing the phrase "Chinese Dream" in China, a term that was later adopted as a slogan by Xi Jinping. Friedman, in the magazine Foreign Policy, has attributed the phrase to Peggy Liu and her environmental NGO JUCCCE.

In September 2020, Friedman told CNBC that "Trump is not the American president America deserves, in my opinion. But he definitely is the American president China deserved. We needed to have a president who was going to call the game with China. And Trump has done it, with I would say more grit and toughness than any of his predecessors. I give him credit for that." In November the same year, Friedman observed that Xi Jinping had brought about "an end to four decades of steady integration of China's economy with the West".

Iran
As the Iran nuclear deal agreement reached between Iran and a group of world powers (the P5+1). In Friedman's interview, he mentioned that "Our view of the Middle East is deeply colored by Israel, Saudi Arabia and Turkey and they all have their own interest. 15 of the 19 hijackers on 911 were from Saudi Arabia, none from Iran! Iranians had a spontaneous demonstration to support Americans on 911." He added, "What strikes you most about Iran (vs. Saudi Arabia) is that Iran has real politics... A country of 85 million people, a great civilization, many educated men and women, if they want to get a bomb they will get it. They have demonstrated they could do it under the most severe sanctions... Show me where Iranians have acted reckless [like Saddam Hussein]. These are survivors."

Radical centrism
In the 2010s, Friedman wrote several columns supporting the politics of radical centrism. In one he stated that, if the "radical center wants to be empowered, it can't just whine.  It needs its own grass-roots movement".  In another column Friedman promoted Americans Elect, an organization trying to field a radical-centrist candidate for the 2012 U.S. presidential election.  That column decried "the two-party duopoly that has dominated American political life".   Friedman's radical-centrist columns received a considerable amount of criticism, particularly from liberals.

Criticism

American journalist Glenn Greenwald, writing for Salon on July 25, 2012, commented: "His status among American elites is the single most potent fact for understanding the nation's imperial decline."

John Esposito criticized him in 2014 for writing twice that Muslims do not speak up against terrorism, and yet "his own newspaper has had these denunciations [by Muslims]."

Some critics have derided Friedman's idiosyncratic prose style, with its tendency to use mixed metaphors and analogies. Walter Russell Mead described his prose as being "an occasionally flat Midwestern demotic punctuated by gee-whiz exclamations about just how doggone irresistible globalization is – lacks the steely elegance of a Lippmann, the unobtrusive serviceability of a Scotty Reston or the restless fireworks of a Maureen Dowd and is best taken in small doses."  Similarly, journalist Matt Taibbi has said of Friedman's writing that, "Friedman came up with lines so hilarious you couldn't make them up even if you were trying – and when you tried to actually picture the 'illustrative' figures of speech he offered to explain himself, what you often ended up with was pure physical comedy of the Buster Keaton/Three Stooges school, with whole nations and peoples slipping and falling on the misplaced banana peels of his literary endeavors."

In a column for the New York Press, Alexander Cockburn wrote: "Friedman exhibits on a weekly basis one of the severest cases known to science of Lippmann's condition, named for the legendary journalistic hot-air salesman, Walter Lippmann, and alluding to the inherent tendency of all pundits to swell in self-importance to zeppelin-like dimensions". Cockburn said Friedman's hubris allowed him to pass off another war correspondent's experience in Beirut as his own.
In December 2017, Hamid Dabashi wrote about Friedman: "Thomas Friedman is an ignorant fool - and I do not mean that as an insult. I mean it as a clinical diagnosis of an almost-illiterate man who has been cheated out of a proper undergraduate education, sold as a liberal Zionist to the highest bidder, and thus has managed to ramble and blabber his way up as a top-notch New York Times columnist."

In November 2017 Mehdi Hasan criticized "Saudi Arabia's Arab Spring, at Last", a column written by Friedman, in which the latter characterized Mohammed bin Salman as a modernizing reformer and a champion of a moderate form of Islam. Hasan described Friedman's article as "nauseating", and suggested that "if the Saudi Arabian government were to set up a Ministry of Truth and Propaganda, they could offer the job of minister to Tom Friedman", critiquing the piece for only mentioning the Yemeni Civil War in passing despite Saudi Arabia and bin Salman's significant involvement in the conflict, and arguing that Friedman's claim that bin Salman was returning Saudi Islam to a state of moderation that existed before the 1979 Grand Mosque seizure in Mecca ignored the long history of ties between the Salafi movement and the House of Saud.

In April 2018, Barrett Brown criticized Friedman for "his serial habit of giving the benefit of the doubt to whoever happens to hold power", such as Friedman's column supporting Vladimir Putin as a modernizing reformer, in which he urged Americans to "keep rootin' for Putin". Brown also used this phrase in the title of his 2014 book "Keep Rootin' for Putin: Establishment Pundits and the Twilight of American Competence".

Documentaries
Friedman has hosted several documentaries for the Discovery Channel from several locations around the world. In Straddling the Fence (2003), he visited the West Bank and spoke to Israelis and Palestinians about the Israeli West Bank barrier and its impact on their lives. Also in 2003, Thomas L. Friedman Reporting: Searching for the Roots of 9/11 aired on the Discovery Times Channel. This program investigated how the Sept. 11 attacks in New York, Pennsylvania, and the Pentagon were viewed in the Muslim world.

In The Other Side of Outsourcing (2004), he visited a call center in Bangalore, interviewing the young Indians working there, and then traveled to an impoverished rural part of India, where he debated the pros and cons of globalization with locals (this trip spawned his later book The World is Flat).

In Does Europe Hate Us? (2005), Friedman traveled through Britain, France and Germany, talking with academics, journalists, Marshall and Rhodes scholars, young Muslims and others about the nature of the strained relationship between Europe and the United States.

Addicted to Oil (2006) premiered at the Silverdocs Documentary Festival at 5:30 PM on June 16, 2006, and aired on June 24, 2006, on the Discovery Times Channel.  In it he examined the geopolitical, economic, and environmental consequences of petroleum use and ways that green technologies such as alternative fuels and energy efficiency and conservation can reduce oil dependence.

In Green: The New Red, White and Blue (2007), Friedman elaborates on the green technologies and efforts touched on in Addicted to Oil and in doing so, attempts to redefine green energy as geostrategic, geoeconomic, capitalistic and patriotic.  He explores efforts by companies and individuals to reduce their carbon footprint and save money with conservation, efficiency, and technologies such as solar, wind, biomass, nuclear, and clean coal.

In 2014, Friedman served as a correspondent for Years of Living Dangerously, a documentary show about climate change. For the show's first season, he traveled to cover the role climate change has played in conflicts in the region. He also interviewed U.S. President Barack Obama. For the show's second season in 2016, he traveled to Africa.

Personal life
Friedman's wife, Ann (née Bucksbaum) is  a teacher and a native of Marshalltown, Iowa. A graduate of Stanford University and the London School of Economics, she is the daughter of real estate developer Matthew Bucksbaum, whom Friedman describes as his "best friend". They were married in London on Thanksgiving Day 1978 and live in an 11,400-square-foot mansion in Bethesda, Maryland. They have two daughters, Orly (born 1985) and Natalie (born 1988).

Friedman supported Hillary Clinton for President of the United States in the 2016 election, and supported Michael Bloomberg in the 2020 primaries. He supported Joe Biden in the 2020 United States presidential election.

Friedman is on the board of directors for Planet Word, a Washington, D.C. based private museum dedicated to language.

Awards and recognition
Friedman has won the Pulitzer Prize three times:
 1983: for his coverage of the war in Lebanon. A distinguished example of international reporting
 1988: for coverage of Israel: a distinguished example of reporting on international affairs
 2002: for his commentary illuminating the worldwide impact of the terrorist threat

Additionally, in 2004 he was elected as a member of the Pulitzer Prize Board, from which he retired in 2013.

In 2003, he received the Golden Plate Award of the American Academy of Achievement. He was elected to the American Philosophical Society that same year.

Published works
 From Beirut to Jerusalem (1989; expanded edition 1990) – winner of the National Book Award in its first edition
 The Lexus and the Olive Tree: Understanding Globalization (1999; revised edition 2000)
 Longitudes and Attitudes: Exploring the World After September 11 (2002; reprinted 2003 as Longitudes and Attitudes: The World in the Age of Terrorism)
 The World Is Flat: A Brief History of the Twenty-first Century (2005; expanded edition 2006; revised edition 2007)
 Hot, Flat, and Crowded: Why We Need a Green Revolution—And How It Can Renew America (2008)
 That Used to Be Us: How America Fell Behind in the World It Invented and How We Can Come Back (Co-written with Michael Mandelbaum 2011)
 Thank You for Being Late: Finding a Job, Running a Country, and Keeping Your Head in an Age of Accelerations (November 2016)

See also
 Curiosity quotient
 New Yorkers in journalism

References

External links

 Columns for The New York Times

1953 births
Living people
Alumni of St Antony's College, Oxford
American columnists
American male journalists
American non-fiction environmental writers
Brandeis University alumni
Bucksbaum family
Carnegie Council for Ethics in International Affairs
George Polk Award recipients
Jewish American journalists
Jewish American writers
Marshall Scholars
National Book Award winners
Writers from Bethesda, Maryland
People from St. Louis Park, Minnesota
Pulitzer Prize for Commentary winners
Pulitzer Prize for International Reporting winners
Radical centrist writers
The New York Times columnists
University of Minnesota alumni
Writers about globalization
Writers from Minnesota
Members of the American Philosophical Society

Thomas Friedman


A scientific demonstration is a procedure carried out for the purposes of demonstrating scientific principles, rather than for hypothesis testing or knowledge gathering (although they may originally have been carried out for these purposes).

Most scientific demonstrations are simple laboratory demonstrations intended to demonstrate physical principles, often in a surprising or entertaining way. They are carried out in schools and universities, and sometimes in public demonstrations in popular science lectures and TV programs aimed at the public. Many scientific demonstrations are chosen for their combination of educational merit and entertainment value, which is often provided by dramatic phenomena such as explosions.

Public scientific demonstrations were a common occurrence in the Age of Enlightenment, and have long  been a feature of the British Royal Institution Christmas Lectures, which date back to 1825. In the television era, scientific demonstrations have featured in science-related entertainment shows such as MythBusters and Brainiac: Science Abuse.

Many scientific demonstrations are potentially dangerous, and should not be attempted without considerable laboratory experience and appropriate safety precautions. Many older well-known scientific demonstrations, once mainstays of science education, are now effectively impossible to demonstrate to an audience without breaking health and safety laws. Some older demonstrations, such as allowing the audience to play with liquid mercury, are sufficiently dangerous that they should not be attempted by anyone under any circumstances.

See also
 Demonstration (teaching)
 List of scientific demonstrations
 Physics Instructional Resource Association
 Science in the Age of Enlightenment
 Technology demonstration

References

Science education
Entertainment

Scientific demonstration


King v. Chapman is a 1945 court case between Primus King, a religious leader and barber in Columbus, Georgia, and  J. E. Chapman, Jr., the chair of the Muscogee County Democratic Party. It ruled the white primary as used by the Democratic Party of Georgia to be unconstitutional. This case followed the Smith v. Allwright case, which struck down the white primaries in Texas and began the downfall of white primaries in other Deep South states.

Background and ruling

On July 4, 1944, Primus E. King, an African-American registered voter, went to the Muscogee County Courthouse in Columbus to cast his vote in the Democratic Party's primary election. He was turned away by law enforcement. Dr. Thomas Brewer, a local physician who co-founded the local branch of the NAACP, encouraged and financially supported Mr. King in his lawsuit filed in federal court. In a landmark ruling in 1945, the United States District Court for the Middle District of Georgia found in Mr. King's favor, deciding that the exclusion of black voters was unconstitutional under the Fourteenth, Fifteenth and Seventeenth Amendments. The U.S. Court of Appeals affirmed, and the U.S. Supreme Court refused to hear the appeal by Chapman, which ended the white primary in Georgia.

Impact
The end of the white primary in Georgia allowed African Americans to pursue the right to vote in Georgia for the first time, although the enforcement of poll taxes, literacy tests and the County Unit System would remain a significant barrier to most African-American voters in Georgia until the 1960s. It would take nearly two decades before Leroy Johnson, the first African American to serve in the Georgia General Assembly, would be elected.

King v. Chapman also served as an inspiration to Martin Luther King Jr., then a 15-year-old who was admitted to Morehouse College.

References

1944 in United States case law
20th-century American trials
African-American segregation in the United States
Civil rights movement case law
History of voting rights in the United States
United States district court cases
United States elections case law
United States equal protection case law
United States Fourteenth Amendment case law
United States Fifteenth Amendment case law
United States Seventeenth Amendment case law
Primary elections in the United States
Democratic Party (United States) litigation
Politics of Georgia (U.S. state)
Georgia (U.S. state) elections
Democratic Party of Georgia
United States District Court case articles without infoboxes
United States racial discrimination case law

King v. Chapman


Giorgio di Sant' Angelo (Jorge Alberto Imperatrice), commonly known as Giorgio Sant'Angelo, (19331989) was an Italian/Argentinian fashion designer based in the United States. He was known for creating ethnic-inspired looks early in his career, for which he won the prestigious American Coty Fashion Critic's award in 1968 and in 1970.  Using fabrics like tie-dyed chiffon, leather and cotton, he created romantic clothing that reflected the hippie culture of the era.  But his innovative use of knitwear, which he continuously developed throughout his career, was often his signature and was an influence on other designers.

Early years

Sant'Angelo was born as Jorge Alberto Imperatrice in Rosario, Argentina, to a middle class family. Son of Domingo Antonio Imperatrice and Leila Ratti, he had a younger brother, Hector Daniel Imperatrice (born 10/4/1945). Later in life, he said he was born a nobleman in Florence, Italy, the son of a Florentine count.

He received a degree in architecture at the University of Florence, then studied industrial design and ceramics.  He also studied with Picasso for six months, as the result of winning an international ceramics competition, sponsored by the French government. Picasso encouraged his student to "trust his own restless creativity and to keep on trying new artistic ventures,"  and Sant'Angelo created an animated film cartoon and submitted it to Walt Disney.  Impressed by the film's inventiveness, Disney brought him to Hollywood and gave him an apprenticeship.  But unable to speak English well, Sant'Angelo was lost in the vastness of Los Angeles and quit after 15 days.

New York

Sant'Angelo moved to New York City after his experience at Disney.  He first worked as textile artist, and later worked in interior design.  For fun, he started making Lucite and plastic jewelry.  Catherine Murray di Montezemolo first noticed the jewelry, then later Diana Vreeland, who started featuring it in Vogue magazine.  This set his career into motion.  Ms. Vreeland recognized the talent that Sant'Angelo showed, and hired him as a freelance stylist.  It was out of this collaboration that some of the most iconic fashion photographs of the 1960s were taken.  Shots like the model Verushka wrapped in fur in the desert, or psychedelic flower makeup around one of Twiggy's eyes.

Seventh Avenue

Sant'Angelo opened his own ready-to-wear business in 1966.  He experimented with knits, and developed new fabrications with textile mills like DuPont.  He also collaborated with textile converters like Crantex, to create his own prints, and leather makers like Calderon, for his accessories.  He cited various native and ethnic cultures as the inspiration for his collections, like the American Indian or the Bohemian Gypsy.  But his most important contribution to modern women's clothing at the time was his liberating construction techniques and his use of stretch fabrics.  He rejected the traditional shift with the zipper-up-the-back, and instead, designed clothing that wrapped, tied, hung or clung to the body. He didn't simply design clothes, he ornamented the body and made fantasy wearable.  He made couture pieces for celebrities and entertainers as well.  Eventually, he started to license his name and expand into cheaper, more affordable clothing.  The first line was called Sant'Angelo 4U2, which were less expensive versions of his fantasy pieces.  Then there was the 'Marjer Parts' line, which was also more affordable, but more trend-influenced.  Later, he dropped the 'di' from his last name and licensed out his name as Giorgio Sant'Angelo. Unfortunately, much of that clothing did not have his own hand involved, and instead, was overly commercial and did not possess his innovative signature. In 1976, Sant'Angelo befriended guitarist Michael Laucke, whom he met through jewelry designer, philanthropist and former fashion model Elsa Peretti, and Sant'Angelo frequently hired Laucke to play at the launching of his new lines in New York, setting "the pace for a more subdued Sant'Angelo".

Comeback

In the mid-1980s, Sant'Angelo added the "di" back to his last name and continued to design his high end signature line.  Made almost entirely out of stretch knits, critics hailed it, confirming the return of his influence.  The versatile, wrap stretch pieces of clothing, in unique materials, colors and patterns, proved an antidote to the overly tailored styles of the time. Unfortunately, di Sant'Angelo died of lung cancer in 1989, so his comeback was short-lived.  But his legend continues in the minds of modern-day fashionistas, with designers like John Galliano and Marc Jacobs citing him as an influence.  He was given a plaque on the 7th Avenue walk of fame along with his contemporaries such as Halston and Stephen Burrows.

References

 Life magazine, article on Giorgio di Sant'Angelo titled 'Fantasy Fashions', 7 March 1969
 New York Fashion, The Evolution of American Style, by Caroline Reynolds Milbank, book published by Harry N. Abrams, 1989
 The Fashion Makers, by Bernadine Morris & Barbara Walz, book published by Random House, 1978

External links

 19331989 Giorgio di Sant' Angelo

1933 births
1989 deaths
Deaths from lung cancer
American fashion designers

Giorgio di Sant' Angelo


The Sil Canyon () is a gorge in Galicia, Spain along the Sil. It covers the last 50 km before the Sil enters the Minho. The scenery is considered to be the most spectacular in Galicia.

The walls rise almost vertically up to 500 m from water level. Due to the extraordinary terrain, the local climate differs from surrounding areas and allows the growth of Mediterranean vegetation, such as  olive trees. The river cliffs have been terraced to allow production of grape vines. Wine production started in this area already in Roman times. The area is called the Ribeira Sacra wine region, and it is  the only place in Galicia that produces more red than white wine.

The gorge is classified in Natura 2000 as a site of community importance. It is a home to several rare bird species, and some mammals such as otters and bats.

References

Landforms of Galicia (Spain)
Canyons and gorges of Spain
Natura 2000 in Spain
Protected areas of Galicia (Spain)
Tourism in Galicia (Spain)

Sil Canyon


Jill Bolte Taylor (; born May 4, 1959) is an American neuroanatomist, author, and public speaker.

Taylor began to study severe mental illnesses because of her brother's psychosis. In the early 1990s, she was a postdoctoral fellow at Harvard Medical School, where she was involved in mapping the brain to determine how cells communicate with each other. On December 10, 1996, Taylor had a massive stroke. Her personal experience with a stroke and her subsequent eight-year recovery influenced her work as a scientist and speaker. It is the subject of her 2006 book My Stroke of Insight, A Brain Scientist's Personal Journey.  She gave the first TED talk that went viral on the Internet,, after which her book became a New York Times bestseller.

In May 2008 she was named to Time Magazine's 2008 Time 100 list of the 100 most influential people in the world. "My Stroke of Insight" received the top "Books for a Better Life" Book Award in the Science category from the New York City Chapter of the National Multiple Sclerosis Society in 2009.

Taylor founded the nonprofit Jill Bolte Taylor Brains, Inc., she is affiliated with the Indiana University School of Medicine, and she is the national spokesperson for the Harvard Brain Tissue Resource Center.

Stroke
On December 10, 1996, Taylor woke up to discover that she was experiencing a stroke. The cause proved to be bleeding from an abnormal congenital connection between an artery and a vein in the left hemisphere of her brain, an arteriovenous malformation (AVM). Three weeks later, on December 27, 1996, she underwent major brain surgery at Massachusetts General Hospital (MGH) to remove a golf ball-sized clot that was placing pressure on the language centers in the left hemisphere of her brain.

My Stroke of Insight
Taylor's February 2008 TED Conference talk about her memory of the stroke garnered widespread attention. It became the second most viewed TED talk of all time.

Following her stroke, Taylor published My Stroke of Insight: A Brain Scientist's Personal Journey, about her recovery from the stroke and the insights she gained into the workings of her brain because of it. Published in May 2008, it spent 63 weeks on the New York Times Bestseller List, reaching number 4.

Taylor appeared on The Oprah Winfrey Show on October 21, 2008. In her later commencement address at Duke University on May 10, 2009, Winfrey quoted Taylor's assertion that "You are responsible for the energy that you bring" and encouraged the students to assume this same responsibility in their future lives. Taylor was the first guest featured on Oprah's Soul Series podcast.

Ballet
Cedar Lake Ballet Company made a ballet about My Stroke of Insight called "Orbo Novo." Deborah Jowitt from The Village Voice wrote: "The piece's title, Orbo Novo, is drawn from a 1493 reference to North America by Spanish historian Pietro Martire d'Anghiera. The "new world" that Cherkaoui is exploring, however, is current theories about the brain, and the text that the seventeen dancers speak during the first moments of the 75-minute work comes from My Stroke of Insight, neuroanatomist Jill Bolte Taylor's uncanny recollection of her stroke. The choreography is based on the ramifications of a single resonant idea: the duality between rationality (the left brain) and instinctive, sensual responses (the right brain); between control and the lack of it; between balance and instability, solitude and society."

The Cecilia Chorus of New York
On May 3, 2019, on the occasion of Taylor's 60th birthday, the Cecilia Chorus of New York presented the world premiere of Fifty Trillion Molecular Geniuses at New York City's Carnegie Hall, setting text from My Stroke of Insight to the music of Johannes Brahms and Edward Elgar.

References

External links

 Jill Bolte Taylor on Oprah's Soul Series
 NPR radio interview
 In a Single Stroke: The Metamorphosis of Jill Bolte Taylor. O, The Oprah Magazine, October 2002
 Interview for the podcast Love + Radio

1959 births
Living people
American neuroscientists
Harvard Medical School alumni
Indiana State University alumni
Indiana University alumni
Indiana University faculty
People with hypoxic and ischemic brain injuries
American women neuroscientists
Writers from Louisville, Kentucky
Kentucky women health professionals
American women physicians
American women academics
21st-century American women

Jill Bolte Taylor


Mars is the fourth planet and the furthest terrestrial planet from the Sun. The reddish color of its surface is due to finely grained iron(III) oxide dust in the soil, giving it the nickname "the Red Planet". Mars's radius is second smallest among the planets in the Solar System at . The Martian dichotomy is visible on the surface: on average, the terrain on Mars's northern hemisphere is flatter and lower than its southern hemisphere. Mars has a thin atmosphere made primarily of carbon dioxide and two irregularly shaped natural satellites: Phobos and Deimos.

Geologically, Mars is fairly active, with dust devils sweeping across the landscape and marsquakes (Martian analog to earthquakes) trembling underneath the ground. The surface of Mars hosts a large shield volcano (Olympus Mons) and one of the largest canyons in the Solar System (Valles Marineris). Mars's significant orbital eccentricity and axial tilt cause large seasonal changes to the polar ice caps' coverage and temperature swings between  to  on the surface. A Martian solar day (sol) is equal to 24.5 hours and a Martian solar year is equal to 1.88 Earth years.

Like the other planets in the Solar System, Mars was formed approximately 4.5 billion years ago. During the Noachian period from about 4.1 to 3.7 billion years ago, Mars's surface was marked by meteor impacts, valley formation, erosion, and the possible presence of water oceans. The Hesperian period from 3.7 to 3.2–2 billion years ago was dominated by widespread volcanic activity and flooding that carved immense outflow channels. The Amazonian period, which continues to the present, was marked by the wind's influence on geological processes. It is unknown whether life has ever existed on Mars.

Mars is among the brightest objects in Earth's sky, and thus has been known from ancient times. Its high-contrast albedo features make it a common subject for viewing with a telescope. Since the late 20th century, Mars has been explored by uncrewed spacecraft and rovers, with the first flyby by the Mariner 4 probe in 1965, the first Mars orbiter by the Mars 2 probe in 1971, and the first landing by Viking 1 in 1976. As of 2023, there are at least 11 active probes orbiting Mars or at the Martian surface. Currently, Mars is an attractive target for the first future interplanetary human missions.

Natural history

Scientists have theorized that during the Solar System's formation, Mars was created as the result of a random process of run-away accretion of material from the protoplanetary disk that orbited the Sun. Mars has many distinctive chemical features caused by its position in the Solar System. Elements with comparatively low boiling points, such as chlorine, phosphorus, and sulfur, are much more common on Mars than on Earth; these elements were probably pushed outward by the young Sun's energetic solar wind.

After the formation of the planets, all were subjected to the so-called "Late Heavy Bombardment". About 60% of the surface of Mars shows a record of impacts from that era, whereas much of the remaining surface is probably underlain by immense impact basins caused by those events. There is evidence of an enormous impact basin in the Northern Hemisphere of Mars, spanning , or roughly four times the size of the Moon's South Pole – Aitken basin, the largest impact basin yet discovered. This theory suggests that Mars was struck by a Pluto-sized body about four billion years ago. The event, thought to be the cause of the Martian hemispheric dichotomy, created the smooth Borealis basin that covers 40% of the planet.

The geological history of Mars can be split into many periods, but the following are the three primary periods:
 Noachian period: Formation of the oldest extant surfaces of Mars, 4.5 to 3.5 billion years ago. Noachian age surfaces are scarred by many large impact craters. The Tharsis bulge, a volcanic upland, is thought to have formed during this period, with extensive flooding by liquid water late in the period. Named after Noachis Terra.
 Hesperian period: 3.5 to between 3.3 and 2.9 billion years ago. The Hesperian period is marked by the formation of extensive lava plains. Named after Hesperia Planum.
 Amazonian period: between 3.3 and 2.9 billion years ago to the present. Amazonian regions have few meteorite impact craters but are otherwise quite varied. Olympus Mons formed during this period, with lava flows elsewhere on Mars. Named after Amazonis Planitia.

Geological activity is still taking place on Mars. The Athabasca Valles is home to sheet-like lava flows created about 200 mya. Water flows in the grabens called the Cerberus Fossae occurred less than 20 Mya, indicating equally recent volcanic intrusions. The Mars Reconnaissance Orbiter has captured images of avalanches.

Physical characteristics

Mars is approximately half the diameter of Earth, with a surface area only slightly less than the total area of Earth's dry land. Mars is less dense than Earth, having about 15% of Earth's volume and 11% of Earth's mass, resulting in about 38% of Earth's surface gravity. The red-orange appearance of the Martian surface is caused by ferric oxide, or rust. It can look like butterscotch; other common surface colors include golden, brown, tan, and greenish, depending on the minerals present.

Internal structure

Like Earth, Mars has differentiated into a dense metallic core overlaid by less dense materials. Current models of its interior imply a core consisting primarily of iron and nickel with about 16–17% sulfur. This iron(II) sulfide core is thought to be twice as rich in lighter elements as Earth's. The core is surrounded by a silicate mantle that formed many of the tectonic and volcanic features on the planet, but it appears to be dormant. Besides silicon and oxygen, the most abundant elements in the Martian crust are iron, magnesium, aluminium, calcium, and potassium. The average thickness of the planet's crust is about , with a maximum thickness of . By comparison, Earth's crust averages  in thickness.

Mars is seismically active. In 2019, it was reported that InSight (now offline) had detected and recorded over 450 marsquakes and related events. In 2021 it was reported that based on eleven low-frequency marsquakes detected by the InSight lander the core of Mars was indeed liquid and had a radius of about  and a temperature around 1900–2000 K. The Martian core radius is abnormally large, accounting for more than half the radius of Mars and about half the size of Earth's core. To this, it has been suggested that the core contains some amount of lighter elements like oxygen and hydrogen in addition to the iron–nickel alloy and about 15% of sulfur.

The core of Mars is overlaid by the rocky mantle, which does not seem to have a thermally insulating layer analogous to the Earth's lower mantle. The Martian mantle appears to be solid down to the depth of about 500 km, where the low-velocity zone (partially melted asthenosphere) begins. Below the asthenosphere the velocity of seismic waves starts to grow again; and at the depth of about 1050 km lies the boundary of the transition zone extending down to the core.

Further analysis of data from the InSight lander has suggested that Mars has a liquid core. On 25 October 2023, scientists, helped by information from InSight, reported that Mars has a radioactive magma ocean under its crust.

Surface geology

Mars is a terrestrial planet with a surface that consists of minerals containing silicon and oxygen, metals, and other elements that typically make up rock. The Martian surface is primarily composed of tholeiitic basalt, although parts are more silica-rich than typical basalt and may be similar to andesitic rocks on Earth, or silica glass. Regions of low albedo suggest concentrations of plagioclase feldspar, with northern low albedo regions displaying higher than normal concentrations of sheet silicates and high-silicon glass. Parts of the southern highlands include detectable amounts of high-calcium pyroxenes. Localized concentrations of hematite and olivine have been found. Much of the surface is deeply covered by finely grained iron(III) oxide dust.

Although Mars has no evidence of a structured global magnetic field, observations show that parts of the planet's crust have been magnetized, suggesting that alternating polarity reversals of its dipole field have occurred in the past. This paleomagnetism of magnetically susceptible minerals is similar to the alternating bands found on Earth's ocean floors. One theory, published in 1999 and re-examined in October 2005 (with the help of the Mars Global Surveyor), is that these bands suggest plate tectonic activity on Mars four billion years ago, before the planetary dynamo ceased to function and the planet's magnetic field faded.

The Phoenix lander returned data showing Martian soil to be slightly alkaline and containing elements such as magnesium, sodium, potassium and chlorine. These nutrients are found in soils on Earth. They are necessary for growth of plants. Experiments performed by the lander showed that the Martian soil has a basic pH of 7.7, and contains 0.6% of the salt perchlorate, concentrations that are toxic to humans.

Streaks are common across Mars and new ones appear frequently on steep slopes of craters, troughs, and valleys. The streaks are dark at first and get lighter with age. The streaks can start in a tiny area, then spread out for hundreds of metres. They have been seen to follow the edges of boulders and other obstacles in their path. The commonly accepted theories include that they are dark underlying layers of soil revealed after avalanches of bright dust or dust devils. Several other explanations have been put forward, including those that involve water or even the growth of organisms.

Radiation levels on the surface are on average 0.64 millisieverts of radiation per day, and significantly less than the radiation of 1.84 millisieverts per day or 22 millirads per day during the flight to and from Mars. For comparison the radiation levels in low Earth orbit, where Earth's space stations orbit, are around 0.5 millisieverts of radiation per day. Hellas Planitia has the lowest surface radiation at about 0.342 millisieverts per day, featuring lava tubes southwest of Hadriacus Mons with potentially levels as low as 0.064 millisieverts per day.

Geography and features

Although better remembered for mapping the Moon, Johann Heinrich Mädler and Wilhelm Beer were the first areographers. They began by establishing that most of Mars's surface features were permanent and by more precisely determining the planet's rotation period. In 1840, Mädler combined ten years of observations and drew the first map of Mars.

Features on Mars are named from a variety of sources. Albedo features are named for classical mythology. Craters larger than roughly 50 km are named for deceased scientists and writers and others who have contributed to the study of Mars. Smaller craters are named for towns and villages of the world with populations of less than 100,000. Large valleys are named for the word "Mars" or "star" in various languages; smaller valleys are named for rivers.

Large albedo features retain many of the older names but are often updated to reflect new knowledge of the nature of the features. For example, Nix Olympica (the snows of Olympus) has become Olympus Mons (Mount Olympus). The surface of Mars as seen from Earth is divided into two kinds of areas, with differing albedo. The paler plains covered with dust and sand rich in reddish iron oxides were once thought of as Martian "continents" and given names like Arabia Terra (land of Arabia) or Amazonis Planitia (Amazonian plain). The dark features were thought to be seas, hence their names Mare Erythraeum, Mare Sirenum and Aurorae Sinus. The largest dark feature seen from Earth is Syrtis Major Planum. The permanent northern polar ice cap is named Planum Boreum. The southern cap is called Planum Australe.

Mars's equator is defined by its rotation, but the location of its Prime Meridian was specified, as was Earth's (at Greenwich), by choice of an arbitrary point; Mädler and Beer selected a line for their first maps of Mars in 1830. After the spacecraft Mariner 9 provided extensive imagery of Mars in 1972, a small crater (later called Airy-0), located in the Sinus Meridiani ("Middle Bay" or "Meridian Bay"), was chosen by Merton Davies, Harold Masursky, and Gérard de Vaucouleurs for the definition of 0.0° longitude to coincide with the original selection.

Because Mars has no oceans and hence no "sea level", a zero-elevation surface had to be selected as a reference level; this is called the areoid of Mars, analogous to the terrestrial geoid. Zero altitude was defined by the height at which there is  of atmospheric pressure. This pressure corresponds to the triple point of water, and it is about 0.6% of the sea level surface pressure on Earth (0.006 atm).

For mapping purposes, the United States Geological Survey divides the surface of Mars into thirty cartographic quadrangles, each named for a classical albedo feature it contains. In April 2023, The New York Times reported an updated global map of Mars based on images from the Hope spacecraft. A related, but much more detailed, global Mars map was released by NASA on 16 April 2023.

Volcanoes

The vast upland region Tharsis contain several extinct volcanoes, which include the shield volcano Olympus Mons (Mount Olympus). The edifice is over  wide. Because the mountain is so large, with complex structure at its edges, giving a definite height to it is difficult. Its local relief, from the foot of the cliffs which form its northwest margin to its peak, is over , a little over twice the height of Mauna Kea as measured from its base on the ocean floor. The total elevation change from the plains of Amazonis Planitia, over  to the northwest, to the summit approaches , roughly three times the height of Mount Everest, which in comparison stands at just over . Consequently, Olympus Mons is either the tallest or second-tallest mountain in the Solar System; the only known mountain which might be taller is the Rheasilvia peak on the asteroid Vesta, at .

Impact topography
The dichotomy of Martian topography is striking: northern plains flattened by lava flows contrast with the southern highlands, pitted and cratered by ancient impacts. It is possible that, four billion years ago, the Northern Hemisphere of Mars was struck by an object one-tenth to two-thirds the size of Earth's Moon. If this is the case, the Northern Hemisphere of Mars would be the site of an impact crater  in size, or roughly the area of Europe, Asia, and Australia combined, surpassing Utopia Planitia and the Moon's South Pole–Aitken basin as the largest impact crater in the Solar System.

Mars is scarred by a number of impact craters: a total of 43,000 craters with a diameter of  or greater have been found. The largest exposed crater is Hellas, which is  wide and  deep, and is a light albedo feature clearly visible from Earth. There are other notable impact features, such as Argyre, which is around  in diameter, and Isidis, which is around  in diameter. Due to the smaller mass and size of Mars, the probability of an object colliding with the planet is about half that of Earth. Mars is located closer to the asteroid belt, so it has an increased chance of being struck by materials from that source. Mars is more likely to be struck by short-period comets, i.e., those that lie within the orbit of Jupiter.

Martian craters can have a morphology that suggests the ground became wet after the meteor impacted.

Tectonic sites

The large canyon, Valles Marineris (Latin for "Mariner Valleys", also known as Agathodaemon in the old canal maps), has a length of  and a depth of up to . The length of Valles Marineris is equivalent to the length of Europe and extends across one-fifth the circumference of Mars. By comparison, the Grand Canyon on Earth is only  long and nearly  deep. Valles Marineris was formed due to the swelling of the Tharsis area, which caused the crust in the area of Valles Marineris to collapse. In 2012, it was proposed that Valles Marineris is not just a graben, but a plate boundary where  of transverse motion has occurred, making Mars a planet with possibly a two-tectonic plate arrangement.

Holes and caves
Images from the Thermal Emission Imaging System (THEMIS) aboard NASA's Mars Odyssey orbiter have revealed seven possible cave entrances on the flanks of the volcano Arsia Mons. The caves, named after loved ones of their discoverers, are collectively known as the "seven sisters". Cave entrances measure from  wide and they are estimated to be at least  deep. Because light does not reach the floor of most of the caves, they may extend much deeper than these lower estimates and widen below the surface. "Dena" is the only exception; its floor is visible and was measured to be  deep. The interiors of these caverns may be protected from micrometeoroids, UV radiation, solar flares and high energy particles that bombard the planet's surface.

Atmosphere

Mars lost its magnetosphere 4 billion years ago, possibly because of numerous asteroid strikes, so the solar wind interacts directly with the Martian ionosphere, lowering the atmospheric density by stripping away atoms from the outer layer. Both Mars Global Surveyor and Mars Express have detected ionised atmospheric particles trailing off into space behind Mars, and this atmospheric loss is being studied by the MAVEN orbiter. Compared to Earth, the atmosphere of Mars is quite rarefied. Atmospheric pressure on the surface today ranges from a low of  on Olympus Mons to over  in Hellas Planitia, with a mean pressure at the surface level of . The highest atmospheric density on Mars is equal to that found  above Earth's surface. The resulting mean surface pressure is only 0.6% of Earth's . The scale height of the atmosphere is about , which is higher than Earth's , because the surface gravity of Mars is only about 38% of Earth's.

The atmosphere of Mars consists of about 96% carbon dioxide, 1.93% argon and 1.89% nitrogen along with traces of oxygen and water. The atmosphere is quite dusty, containing particulates about 1.5 μm in diameter which give the Martian sky a tawny color when seen from the surface. It may take on a pink hue due to iron oxide particles suspended in it. The concentration of methane in the Martian atmosphere fluctuates from about 0.24 ppb during the northern winter to about 0.65 ppb during the summer. Estimates of its lifetime range from 0.6 to 4 years, so its presence indicates that an active source of the gas must be present. Methane could be produced by non-biological process such as serpentinization involving water, carbon dioxide, and the mineral olivine, which is known to be common on Mars, or by Martian life.

Compared to Earth, its higher concentration of atmospheric CO2 and lower surface pressure may be why sound is attenuated more on Mars, where natural sources are rare apart from the wind. Using acoustic recordings collected by the Perseverance rover, researchers concluded that the speed of sound there is approximately 240 m/s for frequencies below 240 Hz, and 250 m/s for those above.

Auroras have been detected on Mars. Because Mars lacks a global magnetic field, the types and distribution of auroras there differ from those on Earth; rather than being mostly restricted to polar regions as is the case on Earth, a Martian aurora can encompass the planet. In September 2017, NASA reported radiation levels on the surface of the planet Mars were temporarily doubled, and were associated with an aurora 25 times brighter than any observed earlier, due to a massive, and unexpected, solar storm in the middle of the month.

Climate

Of all the planets in the Solar System, the seasons of Mars are the most Earth-like, due to the similar tilts of the two planets' rotational axes. The lengths of the Martian seasons are about twice those of Earth's because Mars's greater distance from the Sun leads to the Martian year being about two Earth years long. Martian surface temperatures vary from lows of about  to highs of up to  in equatorial summer. The wide range in temperatures is due to the thin atmosphere which cannot store much solar heat, the low atmospheric pressure (about 1% that of the atmosphere of Earth), and the low thermal inertia of Martian soil. The planet is 1.52 times as far from the Sun as Earth, resulting in just 43% of the amount of sunlight.

If Mars had an Earth-like orbit, its seasons would be similar to Earth's because its axial tilt is similar to Earth's. The comparatively large eccentricity of the Martian orbit has a significant effect. Mars is near perihelion when it is summer in the Southern Hemisphere and winter in the north, and near aphelion when it is winter in the Southern Hemisphere and summer in the north. As a result, the seasons in the Southern Hemisphere are more extreme and the seasons in the northern are milder than would otherwise be the case. The summer temperatures in the south can be warmer than the equivalent summer temperatures in the north by up to .

Mars has the largest dust storms in the Solar System, reaching speeds of over . These can vary from a storm over a small area, to gigantic storms that cover the entire planet. They tend to occur when Mars is closest to the Sun, and have been shown to increase global temperature.

Hydrology

Water in its liquid form cannot exist on the surface of Mars due to low atmospheric pressure, which is less than 1% that of Earth, except at the lowest of elevations for short periods. The two polar ice caps appear to be made largely of water. The volume of water ice in the south polar ice cap, if melted, would be enough to cover the entire surface of the planet with a depth of . Large quantities of ice are thought to be trapped within the thick cryosphere of Mars. Radar data from Mars Express and the Mars Reconnaissance Orbiter (MRO) show large quantities of ice at both poles, and at middle latitudes. The Phoenix lander directly sampled water ice in shallow Martian soil on 31 July 2008.

Landforms visible on Mars strongly suggest that liquid water has existed on the planet's surface. Huge linear swathes of scoured ground, known as outflow channels, cut across the surface in about 25 places. These are thought to be a record of erosion caused by the catastrophic release of water from subsurface aquifers, though some of these structures have been hypothesized to result from the action of glaciers or lava. One of the larger examples, Ma'adim Vallis, is  long, much greater than the Grand Canyon, with a width of  and a depth of  in places. It is thought to have been carved by flowing water early in Mars's history. The youngest of these channels is thought to have formed only a few million years ago.

Elsewhere, particularly on the oldest areas of the Martian surface, finer-scale, dendritic networks of valleys are spread across significant proportions of the landscape. Features of these valleys and their distribution strongly imply that they were carved by runoff resulting from precipitation in early Mars history. Subsurface water flow and groundwater sapping may play important subsidiary roles in some networks, but precipitation was probably the root cause of the incision in almost all cases.

Along craters and canyon walls, there are thousands of features that appear similar to terrestrial gullies. The gullies tend to be in the highlands of the Southern Hemisphere and face the Equator; all are poleward of 30° latitude. A number of authors have suggested that their formation process involves liquid water, probably from melting ice, although others have argued for formation mechanisms involving carbon dioxide frost or the movement of dry dust. No partially degraded gullies have formed by weathering and no superimposed impact craters have been observed, indicating that these are young features, possibly still active. Other geological features, such as deltas and alluvial fans preserved in craters, are further evidence for warmer, wetter conditions at an interval or intervals in earlier Mars history. Such conditions necessarily require the widespread presence of crater lakes across a large proportion of the surface, for which there is independent mineralogical, sedimentological and geomorphological evidence. Further evidence that liquid water once existed on the surface of Mars comes from the detection of specific minerals such as hematite and goethite, both of which sometimes form in the presence of water.

Polar caps

Mars has two permanent polar ice caps. During a pole's winter, it lies in continuous darkness, chilling the surface and causing the deposition of 25–30% of the atmosphere into slabs of CO2 ice (dry ice). When the poles are again exposed to sunlight, the frozen CO2 sublimes. These seasonal actions transport large amounts of dust and water vapor, giving rise to Earth-like frost and large cirrus clouds. Clouds of water-ice were photographed by the Opportunity rover in 2004.

The caps at both poles consist primarily of water ice. Frozen carbon dioxide accumulates as a comparatively thin layer about one metre thick on the north cap in the northern winter only, whereas the south cap has a permanent dry ice cover about eight metres thick. This permanent dry ice cover at the south pole is peppered by flat floored, shallow, roughly circular pits, which repeat imaging shows are expanding in some places and retreating in others. The northern polar cap has a diameter of about , and contains about  of ice, which, if spread evenly on the cap, would be  thick. (This compares to a volume of  for the Greenland ice sheet.) The southern polar cap has a diameter of  and a thickness of . The total volume of ice in the south polar cap plus the adjacent layered deposits has been estimated at 1.6 million cubic km. Both polar caps show spiral troughs, which a recent analysis of SHARAD ice penetrating radar has shown are a result of katabatic winds that spiral due to the Coriolis effect.

The seasonal frosting of areas near the southern ice cap results in the formation of transparent 1-metre-thick slabs of dry ice above the ground. With the arrival of spring, sunlight warms the subsurface and pressure from subliming CO2 builds up under a slab, elevating and ultimately rupturing it. This leads to geyser-like eruptions of CO2 gas mixed with dark basaltic sand or dust. This process is rapid, observed happening in the space of a few days, weeks or months, a rate of change rather unusual in geology – especially for Mars. The gas rushing underneath a slab to the site of a geyser carves a spiderweb-like pattern of radial channels under the ice, the process being the inverted equivalent of an erosion network formed by water draining through a single plughole.

Observations and findings of water evidence

In 2004, Opportunity detected the mineral jarosite. This forms only in the presence of acidic water, showing that water once existed on Mars. The Spirit rover found concentrated deposits of silica in 2007 that indicated wet conditions in the past, and in December 2011, the mineral gypsum, which also forms in the presence of water, was found on the surface by NASA's Mars rover Opportunity. It is estimated that the amount of water in the upper mantle of Mars, represented by hydroxyl ions contained within Martian minerals, is equal to or greater than that of Earth at 50–300 parts per million of water, which is enough to cover the entire planet to a depth of .

On 18 March 2013, NASA reported evidence from instruments on the Curiosity rover of mineral hydration, likely hydrated calcium sulfate, in several rock samples including the broken fragments of "Tintina" rock and "Sutton Inlier" rock as well as in veins and nodules in other rocks like "Knorr" rock and "Wernicke" rock. Analysis using the rover's DAN instrument provided evidence of subsurface water, amounting to as much as 4% water content, down to a depth of , during the rover's traverse from the Bradbury Landing site to the Yellowknife Bay area in the Glenelg terrain. In September 2015, NASA announced that they had found strong evidence of hydrated brine flows in recurring slope lineae, based on spectrometer readings of the darkened areas of slopes. These streaks flow downhill in Martian summer, when the temperature is above −23 °C, and freeze at lower temperatures. These observations supported earlier hypotheses, based on timing of formation and their rate of growth, that these dark streaks resulted from water flowing just below the surface. However, later work suggested that the lineae may be dry, granular flows instead, with at most a limited role for water in initiating the process. A definitive conclusion about the presence, extent, and role of liquid water on the Martian surface remains elusive.

Researchers suspect much of the low northern plains of the planet were covered with an ocean hundreds of meters deep, though this theory remains controversial. In March 2015, scientists stated that such an ocean might have been the size of Earth's Arctic Ocean. This finding was derived from the ratio of protium to deuterium in the modern Martian atmosphere compared to that ratio on Earth. The amount of Martian deuterium is eight times the amount on Earth, suggesting that ancient Mars had significantly higher levels of water. Results from the Curiosity rover had previously found a high ratio of deuterium in Gale Crater, though not significantly high enough to suggest the former presence of an ocean. Other scientists caution that these results have not been confirmed, and point out that Martian climate models have not yet shown that the planet was warm enough in the past to support bodies of liquid water. Near the northern polar cap is the  wide Korolev Crater, which the Mars Express orbiter found to be filled with approximately  of water ice.

In November 2016, NASA reported finding a large amount of underground ice in the Utopia Planitia region. The volume of water detected has been estimated to be equivalent to the volume of water in Lake Superior (which is 12,100 cubic kilometres). During observations from 2018 through 2021, the ExoMars Trace Gas Orbiter spotted indications of water, probably subsurface ice, in the Valles Marineris canyon system.

Orbit and rotation

Mars's average distance from the Sun is roughly , and its orbital period is 687 (Earth) days. The solar day (or sol) on Mars is only slightly longer than an Earth day: 24 hours, 39 minutes, and 35.244 seconds. A Martian year is equal to 1.8809 Earth years, or 1 year, 320 days, and 18.2 hours.

The axial tilt of Mars is 25.19° relative to its orbital plane, which is similar to the axial tilt of Earth. As a result, Mars has seasons like Earth, though on Mars they are nearly twice as long because its orbital period is that much longer. In the present day epoch, the orientation of the north pole of Mars is close to the star Deneb.

Mars has a relatively pronounced orbital eccentricity of about 0.09; of the seven other planets in the Solar System, only Mercury has a larger orbital eccentricity. It is known that in the past, Mars has had a much more circular orbit. At one point, 1.35 million Earth years ago, Mars had an eccentricity of roughly 0.002, much less than that of Earth today. Mars's cycle of eccentricity is 96,000 Earth years compared to Earth's cycle of 100,000 years.

Mars approaches Earth in a synodic period of 779.94 days. Earth orbits the Sun the closest to Mars's orbit around the Sun, and Mars orbit is the second closest to Earth after the orbit of Venus. Therefore, their closest approaches, the inferior conjunctions, are the second closest for Earth after those with Venus, and the closest for Mars to any other planet. The gravitational potential difference, and thus the delta-v needed to transfer between Mars and Earth is the second lowest for Earth and the lowest for Mars to any other planet, while transfers can possibly be optimized with Venus flybys.

Moons

Mars has two relatively small (compared to Earth's) natural moons, Phobos (about  in diameter) and Deimos (about  in diameter), which orbit close to the planet. The origin of both moons is unclear, although a popular theory states that they were asteroids captured into Martian orbit.

Both satellites were discovered in 1877 by Asaph Hall and were named after the characters Phobos (the deity of panic and fear) and Deimos (the deity of terror and dread), twins from Greek mythology who accompanied their father Ares, god of war, into battle. Mars was the Roman equivalent to Ares. In modern Greek, the planet retains its ancient name Ares (Aris: Άρης).

From the surface of Mars, the motions of Phobos and Deimos appear different from that of the Earth's satellite, the Moon. Phobos rises in the west, sets in the east, and rises again in just 11 hours. Deimos, being only just outside synchronous orbitwhere the orbital period would match the planet's period of rotationrises as expected in the east, but slowly. Because the orbit of Phobos is below a synchronous altitude, tidal forces from Mars are gradually lowering its orbit. In about 50 million years, it could either crash into Mars's surface or break up into a ring structure around the planet.

The origin of the two satellites is not well understood. Their low albedo and carbonaceous chondrite composition have been regarded as similar to asteroids, supporting a capture theory. The unstable orbit of Phobos would seem to point toward a relatively recent capture. But both have circular orbits near the equator, which is unusual for captured objects, and the required capture dynamics are complex. Accretion early in the history of Mars is plausible, but would not account for a composition resembling asteroids rather than Mars itself, if that is confirmed. Mars may have yet-undiscovered moons, smaller than  in diameter, and a dust ring is predicted to exist between Phobos and Deimos.

A third possibility for their origin as satellites of Mars is the involvement of a third body or a type of impact disruption. More-recent lines of evidence for Phobos having a highly porous interior, and suggesting a composition containing mainly phyllosilicates and other minerals known from Mars, point toward an origin of Phobos from material ejected by an impact on Mars that reaccreted in Martian orbit, similar to the prevailing theory for the origin of Earth's satellite. Although the visible and near-infrared (VNIR) spectra of the moons of Mars resemble those of outer-belt asteroids, the thermal infrared spectra of Phobos are reported to be inconsistent with chondrites of any class. It is also possible that Phobos and Deimos were fragments of an older moon, formed by debris from a large impact on Mars, and then destroyed by a more recent impact upon the satellite.

Human observations and exploration

The history of observations of Mars is marked by oppositions of Mars when the planet is closest to Earth and hence is most easily visible, which occur every couple of years. Even more notable are the perihelic oppositions of Mars, which are distinguished because Mars is close to perihelion, making it even closer to Earth.

Ancient and medieval observations

The ancient Sumerians named Mars Nergal, the god of war and plague. During Sumerian times, Nergal was a minor deity of little significance, but, during later times, his main cult center was the city of Nineveh. In Mesopotamian texts, Mars is referred to as the "star of judgement of the fate of the dead". The existence of Mars as a wandering object in the night sky was also recorded by the ancient Egyptian astronomers and, by 1534 BCE, they were familiar with the retrograde motion of the planet. By the period of the Neo-Babylonian Empire, the Babylonian astronomers were making regular records of the positions of the planets and systematic observations of their behavior. For Mars, they knew that the planet made 37 synodic periods, or 42 circuits of the zodiac, every 79 years. They invented arithmetic methods for making minor corrections to the predicted positions of the planets. In Ancient Greece, the planet was known as . Commonly, the Greek name for the planet now referred to as Mars, was Ares. It was the Romans who named the planet Mars, for their god of war, often represented by the sword and shield of the planet's namesake.

In the fourth century BCE, Aristotle noted that Mars disappeared behind the Moon during an occultation, indicating that the planet was farther away. Ptolemy, a Greek living in Alexandria, attempted to address the problem of the orbital motion of Mars. Ptolemy's model and his collective work on astronomy was presented in the multi-volume collection later called the Almagest (from the Arabic for "greatest"), which became the authoritative treatise on Western astronomy for the next fourteen centuries. Literature from ancient China confirms that Mars was known by Chinese astronomers by no later than the fourth century BCE. In the East Asian cultures, Mars is traditionally referred to as the "fire star" based on the Wuxing system.

During the seventeenth century A.D., Tycho Brahe measured the diurnal parallax of Mars that Johannes Kepler used to make a preliminary calculation of the relative distance to the planet. From Brahe's observations of Mars, Kepler deduced that the planet orbited the Sun not in a circle, but in an ellipse. Moreover, Kepler showed that Mars sped up as it approached the Sun and slowed down as it moved farther away, in a manner that later physicists would explain as a consequence of the conservation of angular momentum. When the telescope became available, the diurnal parallax of Mars was again measured in an effort to determine the Sun-Earth distance. This was first performed by Giovanni Domenico Cassini in 1672. The early parallax measurements were hampered by the quality of the instruments. The only occultation of Mars by Venus observed was that of 13 October 1590, seen by Michael Maestlin at Heidelberg. In 1610, Mars was viewed by Italian astronomer Galileo Galilei, who was first to see it via telescope. The first person to draw a map of Mars that displayed any terrain features was the Dutch astronomer Christiaan Huygens.

Martian "canals"

By the 19th century, the resolution of telescopes reached a level sufficient for surface features to be identified. On 5 September 1877, a perihelic opposition to Mars occurred. The Italian astronomer Giovanni Schiaparelli used a  telescope in Milan to help produce the first detailed map of Mars. These maps notably contained features he called canali, which were later shown to be an optical illusion. These canali were supposedly long, straight lines on the surface of Mars, to which he gave names of famous rivers on Earth. His term, which means "channels" or "grooves", was popularly mistranslated in English as "canals".

Influenced by the observations, the orientalist Percival Lowell founded an observatory which had 30- and 45-centimetre (12- and 18-in) telescopes. The observatory was used for the exploration of Mars during the last good opportunity in 1894, and the following less favorable oppositions. He published several books on Mars and life on the planet, which had a great influence on the public. The canali were independently observed by other astronomers, like Henri Joseph Perrotin and Louis Thollon in Nice, using one of the largest telescopes of that time.

The seasonal changes (consisting of the diminishing of the polar caps and the dark areas formed during Martian summers) in combination with the canals led to speculation about life on Mars, and it was a long-held belief that Mars contained vast seas and vegetation. As bigger telescopes were used, fewer long, straight canali were observed. During observations in 1909 by Antoniadi with an  telescope, irregular patterns were observed, but no canali were seen.

Robotic exploration

Dozens of crewless spacecraft, including orbiters, landers, and rovers, have been sent to Mars by the Soviet Union, the United States, Europe, India, the United Arab Emirates, and China to study the planet's surface, climate, and geology. NASA's Mariner 4 was the first spacecraft to visit Mars; launched on 28 November 1964, it made its closest approach to the planet on 15 July 1965. Mariner 4 detected the weak Martian radiation belt, measured at about 0.1% that of Earth, and captured the first images of another planet from deep space.

Once spacecraft visited the planet during NASA's Mariner missions in the 1960s and 1970s, many previous concepts of Mars were radically broken. After the results of the Viking life-detection experiments, the hypothesis of a dead planet was generally accepted. The data from Mariner 9 and Viking allowed better maps of Mars to be made, and the Mars Global Surveyor mission, which launched in 1996 and operated until late 2006, produced complete, extremely detailed maps of the Martian topography, magnetic field and surface minerals. These maps are available online at websites including Google Mars. Both the Mars Reconnaissance Orbiter and Mars Express continued exploring with new instruments and supporting lander missions. NASA provides two online tools: Mars Trek, which provides visualizations of the planet using data from 50 years of exploration, and Experience Curiosity, which simulates traveling on Mars in 3-D with Curiosity.

, Mars is host to thirteen functioning spacecraft. Eight are in orbit: 2001 Mars Odyssey, Mars Express, Mars Reconnaissance Orbiter, MAVEN, ExoMars Trace Gas Orbiter, the Hope orbiter, and the Tianwen-1 orbiter. Another five are on the surface: the Mars Science Laboratory Curiosity rover, the Perseverance rover, the Ingenuity helicopter, the Tianwen-1 lander, and the Zhurong rover.

Planned missions to Mars include the Rosalind Franklin rover mission, designed to search for evidence of past life, which was intended to be launched in 2018 but has been repeatedly delayed, with a launch date pushed to 2024 at the earliest, with a more likely one sometime in 2028. A current concept for a joint NASA-ESA mission to return samples from Mars would launch in 2026.

Habitability and the search for life

During the late 19th century, it was widely accepted in the astronomical community that Mars had life-supporting qualities, including the presence of oxygen and water. However, in 1894 W. W. Campbell at Lick Observatory observed the planet and found that "if water vapor or oxygen occur in the atmosphere of Mars it is in quantities too small to be detected by spectroscopes then available". That observation contradicted many of the measurements of the time and was not widely accepted. Campbell and V. M. Slipher repeated the study in 1909 using better instruments, but with the same results. It was not until the findings were confirmed by W. S. Adams in 1925 that the myth of the Earth-like habitability of Mars was finally broken. However, even in the 1960s, articles were published on Martian biology, putting aside explanations other than life for the seasonal changes on Mars. Detailed scenarios for the metabolism and chemical cycles for a functional ecosystem were being published as late as 1962.

The current understanding of planetary habitabilitythe ability of a world to develop environmental conditions favorable to the emergence of lifefavors planets that have liquid water on their surface. Most often this requires the orbit of a planet to lie within the habitable zone, which for the Sun is estimated to extend from within the orbit of Earth to about that of Mars. During perihelion, Mars dips inside this region, but Mars's thin (low-pressure) atmosphere prevents liquid water from existing over large regions for extended periods. The past flow of liquid water demonstrates the planet's potential for habitability. Recent evidence has suggested that any water on the Martian surface may have been too salty and acidic to support regular terrestrial life.

The environmental conditions on Mars are a challenge to sustaining organic life: the planet has little heat transfer across its surface, it has poor insulation against bombardment by the solar wind due to the absence of a magnetosphere and has insufficient atmospheric pressure to retain water in a liquid form (water instead sublimes to a gaseous state). Mars is nearly, or perhaps totally, geologically dead; the end of volcanic activity has apparently stopped the recycling of chemicals and minerals between the surface and interior of the planet.

In situ investigations have been performed on Mars by the Viking landers, Spirit and Opportunity rovers, Phoenix lander, and Curiosity rover. Evidence suggests that the planet was once significantly more habitable than it is today, but whether living organisms ever existed there remains unknown. The Viking probes of the mid-1970s carried experiments designed to detect microorganisms in Martian soil at their respective landing sites and had positive results, including a temporary increase in  production on exposure to water and nutrients. This sign of life was later disputed by scientists, resulting in a continuing debate, with NASA scientist Gilbert Levin asserting that Viking may have found life. Tests conducted by the Phoenix Mars lander have shown that the soil has an alkaline pH and it contains magnesium, sodium, potassium and chloride. The soil nutrients may be able to support life, but life would still have to be shielded from the intense ultraviolet light.

A 2014 analysis of Martian meteorite EETA79001 found chlorate, perchlorate, and nitrate ions in sufficiently high concentrations to suggest that they are widespread on Mars. UV and X-ray radiation would turn chlorate and perchlorate ions into other, highly reactive oxychlorines, indicating that any organic molecules would have to be buried under the surface to survive.

Scientists have proposed that carbonate globules found in meteorite ALH84001, which is thought to have originated from Mars, could be fossilized microbes extant on Mars when the meteorite was blasted from the Martian surface by a meteor strike some 15 million years ago. This proposal has been met with skepticism, and an exclusively inorganic origin for the shapes has been proposed. Small quantities of methane and formaldehyde detected by Mars orbiters are both claimed to be possible evidence for life, as these chemical compounds would quickly break down in the Martian atmosphere. Alternatively, these compounds may instead be replenished by volcanic or other geological means, such as serpentinite. Impact glass, formed by the impact of meteors, which on Earth can preserve signs of life, has also been found on the surface of the impact craters on Mars. Likewise, the glass in impact craters on Mars could have preserved signs of life, if life existed at the site.

Human mission proposals
Several plans for a human mission to Mars have been proposed throughout the 20th and 21st centuries, but none have come to fruition. The NASA Authorization Act of 2017 directed NASA to study the feasibility of a crewed Mars mission in the early 2030s; the resulting report eventually concluded that this would be unfeasible. In addition, in 2021, China was planning to send a crewed Mars mission in 2033. Privately held companies such as SpaceX have also proposed plans to send humans to Mars, with the eventual goal to settle on the planet. The moon Phobos has been proposed as an anchor point for a space elevator.

Viewing from Earth

The mean apparent magnitude of Mars is +0.71 with a standard deviation of 1.05. Because the orbit of Mars is eccentric, the magnitude at opposition from the Sun can range from about −3.0 to −1.4. The minimum brightness is magnitude +1.86 when the planet is near aphelion and in conjunction with the Sun. At its brightest, Mars (along with Jupiter) is second only to Venus in apparent brightness. Mars usually appears distinctly yellow, orange, or red. When farthest away from Earth, it is more than seven times farther away than when it is closest. Mars is usually close enough for particularly good viewing once or twice at 15-year or 17-year intervals. As Mars approaches opposition, it begins a period of retrograde motion, which means it will appear to move backwards in a looping curve with respect to the background stars. This retrograde motion lasts for about 72 days, and Mars reaches its peak apparent brightness in the middle of this interval.

The point at which Mars's geocentric longitude is 180° different from the Sun's is known as opposition, which is near the time of its closest approach to Earth. The time of opposition can occur as much as 8.5 days away from the closest approach. The distance at close approach varies between about  due to the planets' elliptical orbits, which causes comparable variation in angular size. The most recent Mars opposition occurred on 8 December 2022, at a distance of about . The average time between the successive oppositions of Mars, its synodic period, is 780 days; but the number of days between successive oppositions can range from 764 to 812.

Mars comes into opposition from Earth every 2.1 years. The planets come into opposition near Mars's perihelion in 2003, 2018 and 2035, with the 2020 and 2033 events being particularly close to perihelic opposition. Mars made its closest approach to Earth and maximum apparent brightness in nearly 60,000 years, , magnitude −2.88, on 27 August 2003, at 09:51:13 UTC. This occurred when Mars was one day from opposition and about three days from its perihelion, making it particularly easy to see from Earth. The last time it came so close is estimated to have been on 12 September 57,617 BC, the next time being in 2287. This record approach was only slightly closer than other recent close approaches.

Optical ground-based telescopes are typically limited to resolving features about  across when Earth and Mars are closest because of Earth's atmosphere.

In culture

Mars is named after the Roman god of war. This association between Mars and war dates back at least to Babylonian astronomy, in which the planet was named for the god Nergal, deity of war and destruction. It persisted into modern times, as exemplified by Gustav Holst's orchestral suite The Planets, whose famous first movement labels Mars "the bringer of war". The planet's symbol, a circle with a spear pointing out to the upper right, is also used as a symbol for the male gender. The symbol dates from at least the 11th century, though a possible predecessor has been found in the Greek Oxyrhynchus Papyri.

The idea that Mars was populated by intelligent Martians became widespread in the late 19th century. Schiaparelli's "canali" observations combined with Percival Lowell's books on the subject put forward the standard notion of a planet that was a drying, cooling, dying world with ancient civilizations constructing irrigation works. Many other observations and proclamations by notable personalities added to what has been termed "Mars Fever". High-resolution mapping of the surface of Mars revealed no artifacts of habitation, but pseudoscientific speculation about intelligent life on Mars still continues. Reminiscent of the canali observations, these speculations are based on small scale features perceived in the spacecraft images, such as "pyramids" and the "Face on Mars". In his book Cosmos, planetary astronomer Carl Sagan wrote: "Mars has become a kind of mythic arena onto which we have projected our Earthly hopes and fears."

The depiction of Mars in fiction has been stimulated by its dramatic red color and by nineteenth-century scientific speculations that its surface conditions might support not just life but intelligent life. This gave way to many science fiction stories involving these concepts, such as H. G. Wells's The War of the Worlds, in which Martians seek to escape their dying planet by invading Earth; Ray Bradbury's The Martian Chronicles, in which human explorers accidentally destroy a Martian civilization; as well as Edgar Rice Burroughs's series Barsoom, C. S. Lewiss novel Out of the Silent Planet (1938), and a number of Robert A. Heinlein stories before the mid-sixties. Since then, depictions of Martians have also extended to animation. A comic figure of an intelligent Martian, Marvin the Martian, appeared in Haredevil Hare (1948) as a character in the Looney Tunes animated cartoons of Warner Brothers, and has continued as part of popular culture to the present. After the Mariner and Viking spacecraft had returned pictures of Mars as a lifeless and canal-less world, these ideas about Mars were abandoned; for many science-fiction authors, the new discoveries initially seemed like a constraint, but eventually the post-Viking knowledge of Mars became itself a source of inspiration for works like Kim Stanley Robinson's Mars trilogy.

See also

Notes

References

Further reading

External links
 Mars Trek – An integrated map browser of maps and datasets for Mars
 Google Mars and Google Mars 3D, interactive maps of the planet
 First TV image of Mars (15 July 1965), CNN News; 15 July 2023

Articles containing video clips
Astronomical objects known since antiquity
Planets of the Solar System
Terrestrial planets

Mars