NASA’s newest planet-hunting spacecraft has already spied and confirmed a third world outside our Solar System — just three months into the vehicle’s science operations. This newly discovered planet, or exoplanet, is relatively close by, orbiting a small star just 53 light-years away. And that means we may be able to study this world more extensively, to figure out what its atmosphere might hold.
The discoverer of these worlds is NASA’s TESS satellite — a spacecraft about the size of a fridge that was launched into orbit around Earth in April. The vehicle is the successor to NASA’s planet-hunting spacecraft, Kepler, which sat nearly 100 million miles from Earth and found thousands of distant exoplanets. Kepler ran out of fuel in October,...