An astronomical research team using the European Southern Observatory’s telescope in La Silla, Chile, may have found the first Earth-like planet orbiting another star. The planet, currently known as 581 c, circles Gliese 581, a red dwarf approximately 20.4 light years from Earth in the constellation Libra. Dr. Stephane Udry of the Geneva Observatory is the lead author of a paper describing the discovery that has been submitted to the journal Astronomy & Astrophysics.
581 c is about five times heavier than Earth, and its surface gravity should be about 1.6 times as strong as Earth’s. The discoverers don’t yet know if it’s rocky (like Earth, in which case its diameter would be about 1.5 times Earth’s) or an iceball (which would mean an even bigger diameter). They do think the average temperature is be somewhere between 32 and 104 degrees Fahrenheit, which is one of the key factors in determining how Earth-like it is.
No word yet on the any potential atmosphere. 581 c orbits Gliese 581 at only one-fourteenth of an AU, meaning that, though the star is much smaller than Earth’s, it would appear about 20 times larger than our Moon in the sky. It may be tide-locked, and should complete a year in about two weeks.
Gliese 581 already has a Neptune-sized planet and another about 8 times the size of Earth.
More information is available in this CNN article. The Astronomy Picture of the Day has posted a photo of Gliese 581.