In a breathtaking discovery, scientists have unearthed an enormous alien planet lurking in the well-known Kepler-139 star system, all thanks to the careful study of the orbits of its neighboring planets.

Dubbed Kepler-139f, this colossal exoplanet weighs in at 35 times the mass of Earth and is twice as massive as Neptune. Its lengthy orbit around its star spans 355 days, yet despite its size, it had eluded detection until now, as detailed in a recent study published in The Astrophysical Journal Letters.

The key hurdle in discovering Kepler-139f stemmed from the limitations of NASA's Kepler space telescope. While Kepler successfully identified nearly 3,000 exoplanets over nine years, it primarily detected those that passed in front of their stars, causing a flicker that alerted astronomers. Unfortunately, any planets in inclined orbits, traveling above or below the line of sight, remained invisible.

However, the presence of multiple planets within the system hinted that even the elusive planet could be indirectly identified. Kepler-139 features three rocky super-Earths, with a fourth gas giant later thrown into the mix. Observations revealed gaps in their orbits, suggesting additional celestial bodies might be present.

Caleb Lammers, a graduate student at Princeton University and co-author of the study, explained, "The challenge isn't just finding non-transiting planets; it's about deducing their positions based on others in the system." This intricate puzzle was tackled head-on.

The Quest for Kepler-139f