Astronomers claim in a new study published in The Astronomical Journal that the planet Kepler-150 f, which has been overlooked for years, is a ‘lost’ planet about the size of Neptune tucked away in distant solar system 3,000 light years from Earth.

Researchers at Yale University revealed in the study that while computer algorithms that scour through the copious amount of data collected by Kepler and other space telescopes in almost all cases identify exoplanets correctly, they do miss out and that’s what happened with the planet Kepler-150 f that orbits in the Kepler-150 system with a long orbit around its sun.

The Kepler Mission found four other planets in the Kepler-150 system — Kepler-150 b, c, d, and e — several years ago. All of them have orbits much closer to their sun than the new planet does. A follow-up visual search revealed the existence of a the new Neptune-sized exoplanet Kepler-150 f. It was discovered using a combination of the planet multiplicity argument, an FP (false positive) probability analysis, and a transition duration analysis.

Kepler-150 f takes 637 days to circle its sun, one of the longest orbits for any known system with five or more planets. All of them have orbits much closer to their sun than the new planet does.

“Only by using our new technique of modeling and subtracting out the transit signals of known planets could we then actually see it for what it really was,” said Joseph Schmitt, graduate student at Yale. “Essentially, it was hiding in plain sight in a forest of other planetary transits,” said Schmitt.