NASA recently confirmed that 3,472 exoplanets have been discovered, but until recent years, very few of those exoplanets have been smaller than Jupiter.
A team of astronomers at Yale found an exoplanet, called Kepler-150 f, about 3,000 lightyears from Earth in the Kepler-150 system. Scientists have known about the system since 2014, but computers had somehow missed the Neptune-sized exoplanet.
The computer programs used to detect exoplanets look for planetary transit signals when the planet will cross in front of the Sun’s path. Considering Kepler-150f’s orbit is 637 days, it makes sense that a computer may have missed that or written it off as an artifact. Kepler scientists need multiple transits to confirm a planet. As the original mission was four years long, Kepler biases short-period planets. Kepler only had the chance to see -150f transit twice.
However, students at Yale used a mathematical approach that has since been published in The Astronomical Journal to find the hidden exoplanet.
Joseph Schmitt, a graduate student at Yale and lead author of the paper, said that Kepler-150 f was simply “hiding in plain sight.”
“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,” Schmitt said in a press release.