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Earth-Size Planets & Diamond WorldsThe year 2011 saw the discovery of a bountiful crop of alien planets. Scientists discovered the darkest world, a diamond world, a new class of rogue worlds and more.
NASA's Kepler space observatory has even found two Earth-size worlds around a star 950 light-years away — the first-ever exoplanets confirmed to be the size of our home planet.
Take a look at the most intriguing alien planet finds of 2011 and cast your vote for your favorite!
Plethora of Rogue WorldsSlide 2 of 23
Plethora of Rogue WorldsIn May, astronomers announced a huge new class of extrasolar planets - the rogue alien planet.
A vast population of Jupiter-mass worlds floats through space without any discernible host star, the study found. While some of these exoplanets could potentially be orbiting a star from very far away, the majority of them most likely have no parent star at all, scientists say.
NEXT: Super-Hot Planet Kepler-21bSlide 3 of 23
Kepler-21b: You Wouldn't Want to Live ThereSlide 4 of 23
Kepler-21b: You Wouldn't Want to Live ThereOn Dec. 1, astronomers announced they found the ultra-hot alien planet Kepler-21b, a world with a surface temperature estimated to be about 2,960 degrees Fahrenheit (1,627 degrees Celsius) — hot enough to melt iron.
Kepler-21b is located 352 light-years from Earth and is 1.6 times bigger than our own planet. It sits just 3.7 million miles (6 million kilometers) from its host star and takes 2.8 days to complete one orbit. Earth, for comparison, zips around the sun at a distance of 93 million miles (150 million km).
NEXT: TrES-2b: The Darkest Alien PlanetSlide 5 of 23
TrES-2b: The Darkest Alien PlanetSlide 6 of 23
TrES-2b: The Darkest Alien PlanetThe discovery of the darkest alien planet yet found was announced in August, when astronomers unveiled the existence of dark planet TrES-2b, a world about 750 light-years away in the direction of the constellation Draco.
The researchers found this gas giant reflects less than 1 percent of the sunlight falling on it, making it darker than any planet or moon seen up to now.
NEXT: The Diamond Planet PSR J1719-1438Slide 7 of 23
The Diamond Planet PSR J1719-1438Slide 8 of 23