Title: What are the chances of life on another planet?
Headings: What are the chances of life on another planet?
What are the chances of life on another planet?
Explore further

Content: So a planet that harbors life can't be too cold or water will freeze, nor can it be too hot or all the water will evaporate. Planets closer to the sun than Earth are too hot, and those farther away are too cold. The surface of Venus, for example, is hot enough to melt lead, and would vaporize any living thing, while the surface of Mars is frozen solid. Life as we know it here on Earth also requires a magnetic field and an atmosphere, both of which protect it from the lethal radiation our parent star, the sun, emits. Earth's magnetic field—generated by its rotating iron core—deflects the solar wind, a continuous stream of high-speed, high-energy particles coming out of the sun. ( As those particles careen by the edges of Earth's atmosphere, they sometime create the phenomenon we call the Northern Lights.) Without the magnetic field there, the solar wind might destroy all life on Earth. As for Earth's atmosphere, it protects life because the water, carbon dioxide and other gases in it absorb solar radiation in its harmful ultraviolet-light form. The parent stars of other solar systems would emit radiation as well, and the planets orbiting them would need the same kind of protection. Of course, life on Earth also alters the chemical composition of the atmosphere—Earth's atmosphere lacked gaseous oxygen until plants started growing here some million years ago.