Exo-Earth search radius: 1,500 light-years

Exo-Earth search radius: 1,500 light-years

*Only a tiny fraction of our galaxy has been searched for possible Earth-type planets. Up until now, only large planets could be found, but search technology is rapidly approaching the point where small rocky planets imilar to Earth might be detectable. Large Jupiter-size planets have been found nearly 28,000 light-years away.

“Terrestrial Planet”

Example: Earth

Mass: 0.003 Jupiter mass

Orbit radius: 93 million miles (150 million km)

*Goal of exoplanet search is to find and alien analog of Earth or “exo-Earth” planet

“Gas Giant”

Example: Jupiter

Mass: 318 Earth masses

Orbit radius: 484 million miles (778 million km)

Huge planet with thick atmosphere of mostly H and He surrounding tiny rock core

Neptune

Mass: 17 Earth masses

Orbit radius 2.8 billion miles (4.6 billion km)

Gas giant with thick atmosphere of H, He, ammonia, methane surrounding tiny rocky core

“Hot Jupiter”

Example: 51 Pegasi b

Mass: about 0.5 Jupiter masses

Orbit radius: less than 4.9 million miles (7.9 million km)

Massive gas giant orbiting close to its star

“Hot Neptune”

Example: Gliese 436 b

Mass: about 22 Earth masses

Orbit radius: 2.7 million million miles (4.4 million km)

Gas giant orbiting close to its star

“Cthonian Planet”

Example: COROT-7b

Mass: less than 9 Earth masses

Orbit radius: 1.6 million miles (2.58 million km)

A “Hot Jupiter” that has lost all of its thick atmosphere, leaving the rocky core

“Super-Earth”

Example: Kepler-22b

Mass: not available; radius is 2.4 x Earth

Orbit radius: 79 million miles (127 million km)

Larger than Earth, smaller than gas giant

“Water World”

Example: GJ 1214b

Mass: 6.55 Earth masses

Orbit radius: 1.33 million miles (2.14 million km)

Super-Earth that may have vast oceans of liquid water

“Super Neptune”

Example: HAT-P-11b

Mass: 25 Earth masses

Orbit radius: 4.9 million miles (7.9 million km)

Somewhat larger and more massive than Neptune

“Rogue Planet”

Example: Cha 110913

Mass: 8 Jupiter masses

Orbits Milky Way galaxy independtly

Ejected from their solar system and not wander between the stars

“Brown Dwarf”

Example Gliese 229B

Mass: 20-50 Jupiter masses

Orbit radius: 3.73 billion miles (6 billion km)

Larger than a planet, smaller than a star

http://www.space.com/13828-alien-planets-kepler-telescope-infographic.html