We now know there are thousands of planets orbiting other stars—extrasolar planets, or “exoplanets.” These systems are very different than astronomers expected. We've found huge gas giant planets huddled close to their stars. We've found "super-Earths" two to 10 times the mass of our own planet. We've found planets orbiting double-star systems. It may turn out that our own solar system is the oddball in the universe.
Despite the unexpected discoveries, the question that drives us remains the same: Are there other planets out there that could, or do, support life?
The Webb telescope will study the atmospheres of exoplanets for the chemical fingerprints of water vapor, methane, ammonia, carbon monoxide, and carbon dioxide — the types of gases that were present on primitive Earth, and on other worlds in the Solar System. Webb will study how gas and dust disks around stars coalesce into planets, and examine the raw materials of those disks with much greater precision than any previous telescope.