"The expectation, in particular with the public, is a yes-or-no answer. Did you find it or didn't you find it?" Jim Green, NASA's chief scientist, told NPR.
But Green says the reality is much more complex. One scientific discovery about extraterrestrial life may give us a small new insight into the universe, but it may be exaggerated by researchers or misunderstood by the public.
The discovery of the meteorite ALH 84001 — which ignited excitement about the possibility of life on Mars — is one example from history.
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Green walks us through another example. Say a scientist is looking at a distant exoplanet roughly the size of Earth, roughly the same distance from a star, with oxygen and clouds in its atmosphere. That means vegetation on the surface of the planet may be generating the oxygen in the atmosphere, and it's possible we've just found life outside our solar system!
"Well, I got news for you, we know that planet, and that planet is Venus," Green said. "We see oxygen in the atmosphere of Venus, and I can guarantee there is no vegetation on the surface of Venus. So that one observation, although it sounded great, doesn't give us the confidence to lean forward and say we found life or could have found life." READ MORE...
