Extraterrestrial Life • Life from or on other planets. • Life not from this Earth. • A meteorite recently found in Antarctica has tiny fossilized shapes that might be fossils, the remains of ancient life. And this meteorite came from Mars!
The “Goldilocks Conditions” • Scientists refer to “life as we know it.” • Most life on Earth requires liquid water and a suitable temperature and atmosphere. • That is “it’s not too hot, it’s not too cold, it’s just right!” • The distance from a star where a planet can have liquid water at the surface is called the Goldilocks Zone.
Just Right! Just Right! Too Hot! Too Cold! • If the Earth were much hotter, water would always be water vapor, a gas. • If the Earth were much colder, water would always be ice, a solid. • But water can exist in all three states, because our temperature is just right!
Life on Earth • Scientists are not sure if all life would have to be like life on Earth. • Life on Earth exists even in hot springs and near volcanic vents. • Maybe life can survive outside the Goldilocks Zone.
Life on Mars? • Since Mars is similar to earth it is an obvious place to start looking. • Spirit and Opportunity have both found signs that show Mars once had a fair amount of liquid water. • If Mars once had water, maybe life evolved there also. • We should go look!
Life on Europa? • While Europa’s surface is frozen, it appears that there might be liquid water below the surface. • Heat from inside Europa could keep the water liquid. • Where there is liquid water, there might be life. • http://discovermagazine.com/brightcove?bcpid=370512060&bclid=533256427&bctid=35410320001
SETI • Search for Extraterrestrial Intelligence. • Astronomers listen for radio signals from space. • Intelligent races should have radios, so might try to contact others.