Caltech Scientists Discover 3 Smallest Planets Outside Solar System

Artist conception of a red dwarf star. Photo courtesy of NASA via Wikipedia.

Pasadena's California Institute of Technology (Caltech) announced today that a team of astronomers led by Caltech scientists have discovered three of the smallest confirmed planets ever detected outside our solar system, increasing the likelihood of the existence of habitable planets.

The outer-most planet is roughly half the size of Earth, like Mars. The other two are about three-fourths the size of our planet and smaller than Venus. Orbiting a red dwarf star in about two days, the tiny trio ranges in temperatures from 400 degrees to 900 degrees. Though uninhabitable, the rocky planets indicate a likely large number of similar planets in the galaxy, reports City News Service. Those planets could possibly support life.

One factor that especially impressed the astronomers was that they found the planets while examining a small sample of red dwarf stars. "When you combine that with the fact that these are some of the most numerous stars in the galaxy, you realize this type of system could be common,'" said Philip Muirhead, a postdoctoral scholar at Caltech. "There's no question that it's exciting.''

John Johnson, assistant professor of astronomy and research team member, noted that approximately 80% of the galaxy's stars are red stars. "That boosts the chances of other life being in the universe - that's the ultimate result here,'' he said. "If these planets are as common as they appear - and because the red dwarfs themselves are so common - then the whole galaxy must be just swarming with little habitable planets around faint red dwarfs.''

Johnson added, "The really amazing thing about this system is that the closest size comparison is to Jupiter and its moons," according to the Caltech press release. "This is causing me to have to fully recalibrate my notion of planetary and stellar systems."

The team plans to present their findings during two talks today at the meeting of the American Astronomical Society in Austin, Texas.