It's hot and rocky, but NSF astronomers are calling a distant planet about seven-and-a-half times as massive as Earth the most "Earth-like" planet they have ever discovered. While the planet has a radius about twice that of the Earth, it is the smallest planet yet detected outside our own solar system (extrasolar) and orbits a normal star not much different from our Sun.
All of the nearly 150 other extrasolar planets discovered to date around normal stars have been larger than Uranus, an ice-giant planet in our own solar system that is about 15 times the mass of the Earth.
"We keep pushing the limits of what we can detect, and we're getting closer and closer to finding Earths," said team member Steven Vogt, a professor of astronomy and astrophysics at the University of California, Santa Cruz in an NSF press release.
The newly discovered "super-Earth" orbits the star Gliese 876, located just 15 light years away in the direction of the constellation Aquarius. This star also possesses two larger, Jupiter-size planets. The new planet whips around the star in a mere two days, and is so close to the star's surface that its dayside temperature probably tops 400 to 750 degrees Fahrenheit (200 to 400 degrees Celsius)--oven-like temperatures far too hot for life as we know it.
Nevertheless, the ability to detect the tiny wobble the planet induces in the star gives astronomers confidence that they will be able to detect even smaller rocky planets in orbits more hospitable to life.
"This is the smallest extrasolar planet yet detected and the first of a new class of rocky terrestrial planets," said team member Paul Butler of the Carnegie Institution of Washington. "It's like Earth's bigger cousin."
"Today's results are an important step toward answering one of the most profound questions that mankind can ask: Are we alone in the universe?" said Michael Turner, head of the Mathematical and Physical Sciences directorate at the National Science Foundation (NSF), which provided partial funding for the research.
The team's work, conducted at the Keck Observatory in Hawaii, was also supported by the National Aeronautics and Space Administration (NASA), the University of California and the Carnegie Institution of Washington.
[Source: National Science Foundation]
