Astronomers may have spotted a planet in another galaxy for the first time

The hunt for exoplanets is venturing beyond the Milky Way. Astronomers using NASA's Chandra X-ray Observatory have detected what might be the first signs of a planet in another galaxy. The team noticed dips in X-ray brightness that hint at a planet transiting in front of a star in the Messier 51 (aka M51) galaxy 28 million light-years away. For context, all the exoplanet candidates in the Milky Way are no more than 3,000 light-years from Earth -- this planet would easily set a distance record if...