Probing space for the ingredients of life – or even an ‘Earth twin’

In the search for life elsewhere in the universe, we tend to look for our own image. That may be limiting us in terms of seeing what's really there.

Mention aliens and most people picture beings that somewhat resemble humans or other Earthly inhabitants. But scientists will quickly tell you that this science fiction depiction of an alien is far too limited a view of the possibilities that might exist out there in the cosmos. Even right here on Earth, life takes myriad forms from microscopic single-celled organisms to massive animals and plants. And that's just the life we know. The possibility that life may take an entirely unknown form makes it tricky for scientists to know what to look for or what might be a conclusive sign of life. So when it comes to searching distant planets, "we're kind of going for quality over quantity," says MIT astrophysicist Sara Seager. "Although for each individual planet it will be hard to be fully 100 percent confident there's life there, if we see signs of life on so many planets, that will actually be a great step forward for the search for life."

This piece first appeared in the Nov. 8, 2017 issue of The Christian Science Monitor Daily.