Newly Discovered Planet Isn't Punctual

A newly discovered planet is giving scientists a tough time because of its inability to stick to certain schedule, according to a new study.

Known as PH3c, the elusive orb is located 2,300 light years from Earth and has an atmosphere loaded with hydrogen and helium. Its existence was only just recently realized, as part of the Planet Hunters program, due to its inconsistent orbit time around its sun, as seen from our solar system. The gravitational influence of other planets in its system is to blame.

"On Earth, these effects are very small, only on the scale of one second or so," first author Joseph Schmitt of Yale University said in a statement. "PH3c's orbital period changed by 10.5 hours in just 10 orbits."

That inconsistency kept it from being picked up by automated computer algorithms, which search stellar light curves and identify regular dips caused by objects passing in front of stars.

Luckily, the Planter Hunters program did, thanks to citizen scientists who were asked to check survey data from NASA's planet-hunting Kepler spacecraft.

"It harnesses the human dimension of science," explained co-author Debra Fischer. "Computers can't find the unexpected, but people can, when they eyeball the data."

So not only did Planet Hunters spot PH3c, a low-mass, low-density planet, but the discovery also allowed astronomers to better characterize two other planets - one on each side of PH3c. An outer planet, PH3d, that is slightly larger and heavier than Saturn, and an inner planet named PH3b that may have a rocky composition similar to that of Earth.

"Finding the middle planet was key to confirming the others and allowing us to find their masses," Schmitt said. "The outer planet's orbital period also changes slightly, by about 10 minutes. You need to see both planets' changing orbital periods in order to find out the masses of the planets. One planet doesn't give enough information."

The researchers also found an interesting tidbit about the far-away trio, in which the outer planet's year is 1.91 times longer than the middle planet's year, and the middle planet's year is 1.91 times longer than the inner planet's year. It may help them to better understand how the planets formed.

The findings are described further in The Astrophysical Journal.