Tiny 'compact' distant solar system seen

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GAINESVILLE, Fla., Oct. 16 (UPI) -- U.S. astronomers say they've discovered a tiny distant solar system with five planets orbiting a star at a distance much closer than Earth is to our sun.

The multi-planet system is in tight orbit around the star KOI-500, a star about the mass of the sun but only about 1 billion years old, less than one-quarter the sun's age.

The five planets in the system, the most tightly packed one discovered yet, range in size from 1.3 to 2.6 times the size of Earth.

"All five planets zip around their star within a region 150 times smaller in area than the Earth's orbit, despite containing more material than several Earths," study lead author Darin Ragozzine, a planetary scientist at the University of Florida, said in a statement.

"At this rate, you could easily pack in 10 more planets, and they would still all fit comfortably inside the Earth's orbit."

These five planets orbit so close the their star their "years," or period of their orbit around the star, are only 1.0, 3.1, 4.6, 7.1, and 9.5 days long, SPACE.com reported.

"As the most compact system of a new compact population of planets, KOI-500 will become a touchstone for future theories that will attempt to describe how compact planetary systems form," Ragozzine said.