Over the past two decades astronomers have discovered over 1900 exoplanets but so far there's been no hard evidence to confirm even the existence of extraterrestrial life in our own solar system. Speaking at a public panel on Tuesday in Washington D.C., NASA scientists discussed the probability of finding organic life in our solar system and agreed the question is no longer if but when we'll find it.
NASA Chief Scientist Ellen Stofan said at the panel that she believes strong indications for microbial life elsewhere in our solar system will be found in the next decade and definitive evidence in the next 10 to 20 years.
These statements come after recent discoveries of liquid water on moons around Jupiter, proof that simple life could evolve on moons around gas giants, far from what was previously considered to be the habitable zone around a star.
NASA researchers say these revelations upend the earlier idea that, to find life, we need to look for planets within stars’ “habitable zones.” That theory suggests that in order for a space rock to harbor life, it needs to be at a certain "perfect" distance from a warm body (like Earth is from our sun). That way, the temperature is just right so that water can exist on the planet in liquid form.
But on Europa, liquid water exists even though the frigid moon is more than 400 million miles away from our star. It’s because the gravitational pull from Jupiter jerks the satellite around, causing enough friction and energy to heat up the liquid beneath the surface. Thus, the moon's water can remain as a liquid when it's so far from a light source.