Escaping slavery; risking everything to save her family; leading a military raid; championing the cause of women’s suffrage; these are just a handful of the accomplishments of one of America’s most courageous heroes.
Harriet Tubman was born Araminta Ross in Dorchester County, Maryland, in the early 1820s.
Born into chattel slavery, Araminta, or Minty, was the fifth of nine children.
Two of Minty’s older sisters were sold to a chain gang.
Even as a small child, Minty was hired out to different owners, who subjected her to whippings and punishment.
Young Minty’s life changed forever on an errand to a neighborhood store.
There, an overseer threw a two-pound weight at a fugitive enslaved person, missed, and struck Minty instead.
Her injury caused her to experience sleeping spells, which we know of today as narcolepsy, for the rest of her life.
Minty’s owner tried to sell her, but there were no buyers for an enslaved person who fell into sleeping spells.
She was instead put to work with her father, Ben Ross, who taught her how to lumber.
Lumbering increased Minty’s physical strength and put her in touch with free black sailors who shipped the wood to the North.
From them, Minty learned about the secret communications that occurred along trade routes, information that would prove invaluable later in her life.
In this mixed atmosphere of free and enslaved blacks working side by side, Minty met John Tubman, a free black man she married in 1844.
After marriage, she renamed herself Harriet, after her mother.
Harriet Tubman’s owner died in 1849.
When his widow planned to sell off her enslaved human beings, Harriet feared she would be sold away from everyone she loved.
She had heard of an “underground railroad," a secret network of safe houses, boat captains, and wagon drivers willing to harbor fugitive enslaved people on their way north.
So Tubman fled with two of her brothers, Ben and Harry.
They eventually turned back, fearing they were lost.
But in one of her sleeping spells, Harriet dreamed that she could fly like a bird.
Looking down below, she saw the path to liberation.
And in the autumn of 1849, she set out on her own, following the North Star to Pennsylvania, and to freedom.
Tubman returned to the South 13 times to free her niece, brothers, parents, and many others.
She earned the nickname Black Moses and worked diligently with fellow abolitionists to help enslaved people escape, first to the North, and later to Canada.
Harriet Tubman worked as a Union army nurse, scout, and spy during the Civil War.
In 1863, she became the first woman in United States history to plan and lead a military raid, liberating nearly 700 enslaved persons in South Carolina.
After the war, the 13th Amendment to the U.S. Constitution legally abolished slavery, while the 14th expanded citizenship and the 15th gave voting rights to formerly enslaved black men.
But she was undaunted, and she persisted.
She raised funds for formerly enslaved persons and helped build schools and a hospital on their behalf.
In 1888, Tubman became more active in the fight for women’s right to vote.
In 1896, she appeared at the founding convention of the National Association of Colored Women in Washington D.C.
and later at a woman’s suffrage meeting in Rochester, New York.
There she told the audience: “I was a conductor on the Underground Railroad, and I can say what many others cannot.
I never ran my train off the track, and I never lost a passenger.”
As her fame grew, various friends and allies helped her in the fight to collect a veteran’s pension for her service in the Union Army.
In 1899, she was finally granted $20 a month.
In a fitting twist of fate, the United States Treasury announced in 2016 that Tubman’s image will appear on a redesigned twenty dollar bill.
Harriet Tubman died on March 10, 1913.
Even on her deathbed at age 91, she kept the freedom of her people in mind.
Her final words were: "I go away to prepare a place for you.”
The sky is inherently democratic.
It's accessible, in principle, anyway, by anyone, everywhere, just simply by the act of looking up.
But like so many beautiful things around us, it's slipping away from us, and we haven't even noticed, because we're honestly not really looking.
So what do we look at instead?
Well, we look at our phones, we look at our computers, we look at screens of all kinds.
And honestly, we rarely even take the trouble to look up enough to see each other, let alone taking that next step to looking up at the actual sky.
Now, there's a tendency to think that the loss of our dark night skies is the inevitable outcome of progress, change, technology.
And you know, that's just simply not true.
Later on, I'll tell you why.
But first, I want to tell you about my experience of the dark night sky.
I never saw a truly dark night sky until I was 15.
I was here, in Arizona.
I was on a road trip; I pulled over somewhere.
I have no idea where I was, except I know what state.
And I looked up, and the sky was just filled with an impossible number of stars.
You see, I'm from New York City, and in New York, you can see the moon, you can see a couple of stars.
More often than not, they turn out to be airplanes when they land.
(Laughter) But there's really not much else.
As a result, most of my colleagues who are astronomers spent at least part of their youth looking up at the sky in their backyard.
I never really had that experience, and, as a result, I'm really disappointing on camping trips.
I don't really know many constellations.
The ones I do know, you probably know them, too.
But I'll never forget that experience of the first time I saw the dark night sky.
And I was just flabbergasted at how many stars there were.
And I felt tiny.
Then I also felt like, "Where's this been hiding this whole time?
Who's been hiding this sky from me?"
Of course, the answer is obvious if you think about it or if you look at the picture on the left, where you're seeing the same neighborhood taken during a blackout versus on an ordinary night.
You can't see the stars if you drown them out with light.
Take a look at our planet.
This is our planet from space.
Unlike stars, which are hot and glow invisible light so we can see them, our planet is, astronomically speaking, pretty cold.
So it doesn't really glow.
When you see the planet looking like a blue-green marble the way it does in this picture, you're seeing it because the sunlight is reflecting off of it, and that's why you can see the oceans, the clouds, the land.
So if the sun wasn't shining on it, we wouldn't be able to see the earth, right?
Or would we?
This is our earth at night, and it is one of the most striking examples of how we have affected our planet on a global scale.
You can see light spidering out across the globe everywhere.
Now, of course, there are broad expanses of ocean that are still dark, and in many underdeveloped areas there's still darkness.
But you'll notice that this is a pretty global effect.
We tend to think, when we think of places being lit up, of very extreme examples -- Times Square, the Vegas Strip.
But really what that picture shows you is that it's not just these extreme examples, it's anywhere that uses outdoor lighting.
This tends to be a really dramatic effect on the ground.
To understand why, all you really have to do is think about the shape of a lightbulb.
The lightbulb, for all practical purposes, is more or less round.
This is great for its original intended purpose of lighting up the indoors.
You turn it on, light goes everywhere.
An individual light bulb can light up your whole room, more or less.
Now, that's great if you're lighting the indoors, but in its application in outdoor lighting, that traditional shape of the light bulb, the sort of globe that spreads light everywhere, is actually very inefficient.
When you're outdoors, mostly what you care about is lighting the ground beneath you and your immediate surroundings.
All of that light that gets scattered outwards and upwards doesn't actually help you light the area around you.
What it does is scatters up into the sky and becomes what we call "light pollution."
Even if you don't care anything about stargazing, this should worry you, because it means that 60-70% of the energy we use to light the outdoors is wasted by blotting out the stars.
Now, like I said, I'm a big fan of technology.
Obviously, I use technology every day; I'm a scientist.
And there's this tendency to say that it's progress that -- you know, I'm not suggesting we're going to all go live by candlelight.
Indeed, technology is allowing us to access the sky in ways that are impossible otherwise.
One of the greatest examples of this is, of course, the Hubble Space Telescope.
The Hubble went up into space, it returns pictures daily, and it allows us to see things that we are incapable of seeing with our naked eye, in ways that we've never been able to do before in all of human history.
Other examples of this would be planetarium shows.
In the past couple of years, planetarium shows have become more high-tech with these great visualizations, and even though this isn't access directly to the sky, it's at least access to our knowledge about the sky.
And indeed, we can experience the sky in a planetarium in a way that is impossible for us to do just sitting out and looking in the dark.
All of you have heard of the Hubble Space Telescope and of planetariums.
But there are also ways for technology to enable participation in people's experience of the sky that you may not be familiar with.
These are called "citizen science projects."
Citizen science is when large research projects put their data online, teach ordinary people, like you, to go and interact with that data and actually contribute to the research by making interesting or necessary characterizations about it.
One such example of this is what I'm showing here, called "Galaxy Zoo."
Galaxy Zoo is a project where people get a 20-minute -- even less than that, actually -- tutorial on how to interact with these images of galaxies.
They learn to annotate the images, and within a couple of minutes, they're up and running, and they're making really useful categorizations and classifications of these galaxies.
Now, it's easy to understand why Galaxy Zoo would be an easy sell for people to be involved with: it involves pretty pictures; galaxies are, generally speaking, pretty attractive.
However, there are many other flavors of citizen science projects that people have delved into that have varying levels of abstraction, that you wouldn't necessarily think people would jump at.
One such example of this is the citizen science project associated with the mission that I'm part of, called the Kepler Mission.
Kepler is a space telescope and it looks for planets around other stars by measuring the light from those stars very precisely.
And we're looking for the dimmings caused by stars blocking off some of that light.
We have an associated citizen science project called "Planet Hunters."
Planet Hunters gives you, like Galaxy Zoo, a short tutorial, and within a couple of minutes, you're up and running; you're looking at data from the Kepler Mission and looking for planets.
The idea behind this is an easy sell, right?
But the actual process of planet-hunting involves a lot of looking at graphs, like the one I'm showing you here, and annotating them.
I do this all day and that doesn't even sound that interesting to me.
However, not only are people interested in doing this, but the citizen scientists that work with Planet Hunters have actually found planets in the data that would have gone undiscovered otherwise.
This is an author list from the paper that they published of the planet they discovered.
You'll see that all the people who contributed are listed below, and it's sort of an odd amalgam of people's real names and their log-in names.
You'll notice if you look carefully, this is the first academic acknowledgment of the importance of Irish coffee in the discovery process.
(Laughter) I don't want to give you the idea that these are some out-of-work scientists or just a bunch of nerds that are really into this.
There are 60,000 people who participate in these projects, and most of them don't have technical backgrounds.
So clearly, what this is feeding into is people's curiosity and their willingness to be part of the scientific discovery process.
People want to do this.
But all of this technology and all these digitally mediated ways of experiencing the sky still have something of a feel to me like looking at an animal in a zoo.
It's a valid way of experiencing that thing -- indeed, the lion in the cage is still real, the Hubble images are indeed real, and you can get closer to a lion in a zoo than you can in the wild.
However, it's missing something.
It's missing that savage beauty of experiencing that very thing in the wild for yourself, unmediated by a screen.
The experience of looking up and knowing that the sky you're looking at surrounds every known living thing in the universe is very profound.
Think about that for a moment.
We are the only planet we know of that has life on it.
The sky that you see is shared by every other living thing that we know of in existence.
One of the things that I really like about my work is that it allows me to step back from my every day and to experience the larger context, this feeling that just as we go out and try to find planets in the universe that might be like ours, it always reminds me of how precious what we have here is.
Our night sky is like a natural resource, it's as though it's a park that you can visit without ever having to travel there.
But like any natural resource, if we don't protect it, if we don't preserve it and treasure it, it will slip away from us and be gone.
So if you're interested in this, and this is something you want to learn more about, I encourage you in particular to visit darksky.org and to learn more about the choices you can make that can protect the dark night sky, because it belongs to everyone, it belongs to all of us, and therefore, it's ours to experience as we wish.
And it's also ours to lose.
Thank you.
(Applause)