Harvard Scientists Discover an "Invisible" Planet

Harvard scientists have discovered what they have dubbed an “invisible  planet.”

While the planet is not actually invisible, scientists inferred its existence from “the influence it’s exerting on another planet,” bypassing more traditional methods of detecting planets that rely on visible evidence, lead researcher Sarah A. Ballard said.

Ballard, who is a graduate student in astronomy, found the planet—dubbed Kepler-19c and located 650 light-years from Earth in the constellation Lyra—during a routine examination of data collected from a NASA mission.

She noticed that the orbit of a previously discovered planet, Kepler-19b, was irregular. During its orbit, the planet finished rotating its star five minutes earlier or five minutes later than expected.

She concluded that the gravity of another planet must be pulling on Kepler-19b and causing the inconsistencies in the length of the orbit.

“It’s bullying the planet that’s there,” Ballard said.

According to Ballard, the discovery of Kepler-19c has the potential to usher in a new age of discovery where scientists have the ability to find a massive number of previously unidentified planets.

“I predict there will be thousands of additional planets discovered using this method,” Ballard said. “It’s an entirely new way to find new worlds.”

Over 150 years ago the astronomer Alexis Bouvard used a similar method to identify Neptune, the most distant planet in our solar system. Bouvard deduced Neptune’s presence from unusual patterns in Uranus’s orbit. Neptune’s existence and location was later visually verified through observations from telescopes.

The transit timing variation method used to discover Kepler-19c is only a few years old. It is a modern variation on the process used to identify Neptune.

Ballard said that her discovery represents the “first robust example” of a method that had previously seemed plausible, but was still only a theory.

The discovery of Kepler-19b and Kepler 190c are a part of NASA’S Kepler mission. Launched in 2009, scientists gave the mission the task of discovering alien planets throughout the galaxy.

According to David Charbonneau, a professor of astronomy and co-author of the Ballard’s findings, the Kepler mission was initially designed to use more traditional methods of finding planets, namely detecting the shadows that they cast on stars.

This more customary method required that stars and plans align perfectly and therefore was less productive and effective, he said.

This more traditional method was employed to discover Kepler-19b–the planet that led to the eventual discovery of Kepler-19c.

The transit timing variation method, Charbonneau said, could be the future of planet discovery.

“The idea was not unexpected,” Charbonneau said. “People had for years described this idea as a theoretical construct, a way of finding planets.”

With that theory having graduated beyond theory to tried and true method, Charbonneau said, the prospect of what may still be discovered is “exciting.”

—Staff writer Hana N. Rouse can be reached at hrouse@college.harvard.edu.