For years, planetary scientists have been scouring the heavens in search of planets outside our own solar system. One very long-term goal is to discover a twin to our planet Earth and to search for biological features in its atmospheric spectrum. A shorter-term goal is to understand planetary formation processes more generally.
Since the first sighting of an extrasolar planet in 1995, the search has netted nearly 80 planets, but we know little more about them than their minimum masses and their orbital parameters. 1 It’s been tough enough to glean that much information, which in most cases has been inferred from the tiny, periodic wobble that the planet’s orbital motion produces in the Doppler shift of its parent star. It’s far tougher to detect the planet’s atmospheric constituents. But now a team of researchers 2 has managed to detect atmospheric sodium atoms in a planet orbiting a star known...
