Astronomers have spotted the oldest planetary system ever found, an ancient star and five small, Earthlike planets that are about 11.2 billion years old.
Until now, scientists weren’t certain that rocky planets could have formed so long ago, when the universe was five times younger than it is today. Now they know for sure that they did, according to a new study in the Astrophysical Journal.
The discovery also suggests that ancient life in our universe is more likely than was previously thought, scientists say. “It hints that old system planets are possible,” said author Sarbani Basu, an astronomy professor at Yale. “And if those planets are in the habitable zone, then it is possible we could have old life too.”
The ancient star, Kepler-444, is small and cool — just 75 percent as massive as our sun. It is situated 117 light-years from Earth, in the Milky Way Galaxy.
The planets that orbit it are smaller than Earth — somewhere between the size of Mercury and Venus. They move rapidly around their host star, making a complete orbit in less than 10 days. Because of their size, scientists say they are almost certainly rocky. The five planets that orbit Kepler-444 are too close to their host star to harbor life as we know it, but the study opens up the possibility that an Earthlike planet, and possibly life, could have existed in the early universe.
“Kepler-444 came from the first generation of stars,” said Steve Kawaler, an Iowa State University professor and co-author of the paper. “This system tells us that planets were forming around stars nearly 7 billion years before our own solar system.”
Los Angeles Times