- "It remains possible that there are other unseen planets in the system. The challenge is finding them!"
Scientists have detected a hidden alien planet by examining the orbits of the known worlds in the star system, known as Kepler-139.
The newfound exoplanet, called Kepler-139f, is a gigantic world roughly twice the mass of Neptune and 35 times the mass of Earth, and it takes 355 days to orbit its star, astronomers reported in a study published May 2 in The Astrophysical Journal Letters. Despite its giant size, Kepler-139f had evaded detection.
That's because the initial yield of NASA's Kepler space telescope, which discovered nearly 3,000 planets in its nine years of operation, relied on worlds transiting — passing between their star and Earth. The resulting dimming of the star allowed astronomers to identify planets and calculate their size. But Kepler couldn't see planets traveling above or below the wedge of space between it and the star, so any outliers remained unseen.
