The past decade has brought about a revolution in astronomers’ ability to detect potentially habitable planets, and there’s much, much more to come. The problem will be identifying the likeliest places for life to lurk, and two newly published studies address that problem from two dramatically different perspectives.
One study takes an inward-looking perspective: If we were the aliens, how would we know about Earth?
The best planet-detection method that’s currently available to earthly astronomers looks for the telltale dimming of light as a planet crosses the disk of its parent star. But that dimming, known as a planetary transit, can be seen only when the planet and the alien star are lined up with Earth.
That suggests that Earth is most likely to be detected by observers on alien planets in a narrow strip of the sky where our planet can be seen crossing the sun.