Image 1 - Kepler Discovers First Ever Circumbinary Planet
September 15, 2011

Kepler Finds Tatooine-Like Planet


NASA's Kepler spacecraft has discovered a new planet that orbits around a pair of low-mass stars, not unlike the fictional world of Tatooine from the Star Wars universe, the U.S. space agency announced Thursday afternoon.

"The existence of a world with a double sunset, as portrayed in the film Star Wars more than 30 years ago, is now scientific fact," NASA said in a statement on Thursday. "Unlike Star Wars´ Tatooine, the planet is cold, gaseous and not thought to harbor life, but its discovery demonstrates the diversity of planets in our galaxy."

In a press conference held at the Ames Research Center in Moffett Field, California, Kepler Project Scientist Nick Gautier identified the newly discovered world as a circumbinary planet named Kepler 16b. The new world, he said, had approximately the same mass as Saturn and a 299 day orbit.

Gautier, who works at the Jet Propulsion Laboratory, Pasadena, California, said that Kepler 16b is the first ever confirmed circumbinary planet. The two stars, he said at the media briefing, also orbit each other, and also eclipse each other at specific points.

In a paper detailing the discovery, published Thursday in the journal Science, the Kepler team writes that the stars "are 20 and 69% as massive as the Sun and have an eccentric 41-day orbit. The motions of all three bodies are confined to within 0.5° of a single plane, suggesting that the planet formed within a circumbinary disk."

It is the 21st confirmed planet discovered by Kepler, Gautier said.

"This discovery is stunning," Alan Boss, a researcher at the Carnegie Institution for Science in Washington D.C. and one of the scientists who discovered Kepler-16b, told Guardian Science Correspondent Ian Sample. "Once again, what used to be science fiction has turned into reality."

Sample also reports that the planet lies approximately 200 light years from Earth, and that temperatures there range from -70 degrees Celsius to -100 degrees Celsius (-94 degrees Fahrenheit to -148 degrees Fahrenheit). The rotation period is currently unknown, and the composition of the planet was said to be half rock and half gas.

Kepler is the tenth mission in NASA's Discovery series, and the first with the capability of finding Earth-sized planets in what is known as the habitable zone (the area of a planetary system in which liquid water and exist on an orbiting planet's surface), according to NASA. Its goal, according to the mission's official homepage, is "to help us better understand our place in the galaxy."

To accomplish this mission, Kepler uses a special type of telescope, called a photometer or light meter, that is just under one meter in diameter. This telescope features a 105 square degree field of view, which NASA says "is comparable to the area of your hand held at arm's length," which is necessary in order to observe the large number of stars required for the unit to complete the tasks required.

Kepler was launched on board a Delta II rocket on March 6, 2009, from Cape Canaveral Air Force Base in Florida. Its mission was scheduled to last for approximately 3.5 years, NASA said.

Earlier this month, the space agency reported that the spacecraft had discovered a so-called "invisible planet" -- an unseen world which affected the orbit of another world, making it alternately run early or late because of its gravitational pull on the neighboring planet. It was the first time a planet had been identified using this method, according to a September 8 press release.


Image 1: Where the Sun Sets Twice - NASA's Kepler mission has discovered a world where two suns set over the horizon instead of just one. The planet, called Kepler-16b, is the most "Tatooine-like" planet yet found in our galaxy. Tatooine is the name of Luke Skywalker's home world in the science fiction movie Star Wars. In this case, the planet it not thought to be habitable. It is a cold world, with a gaseous surface, but like Tatooine, it circles two stars. Image credit: NASA/JPL-Caltech/R. Hurt

Image 2: In the Light of Two Suns - This artist's concept illustrates Kepler-16b, the first planet known to definitively orbit two stars -- what's called a circumbinary planet. The planet, which can be seen in the foreground, was discovered by NASA's Kepler mission. Image credit: NASA/JPL-Caltech/T. Pyle


On the Net: