Kepler space telescope finds its first Earth-size planet

William Atkins
Friday, 04 February 2011 01:49

Science - Space

On February 2, 2011, NASA announced that its Kepler space telescope found its first Earth-size planet. In fact, it found five Earth-size planets all orbiting about one star, Kepler-11.

Kepler, named in honor of German astronomer Johannes Kepler, is a space telescope that was launched by NASA on March 7, 2009.

Its planned 3.5-year mission is to monitor over 150,000 main sequence stars and, in the process, to analyze their periodic fluctuations in brightness to see if extrasolar planets (or exoplanets, those outside of our solar system) are orbiting about them.

Five of the six exoplanets found orbiting around the star Kepler-11 are considered the first Earth-size planets identified by the Kepler mission.

Five out of six of these exoplanets are also located within the Goldilocks Zone, or the region about a star in which liquid water could exist on a planet's surface and, thus, have the capability of being habitable (its habitable zone).

Kepler-11, a Sun-like star, is located about 2,000 light-years away from Earth. It is found within the constellations Cygnus.

These six known exoplanets orbiting about Kepler-11 are:

'¢    Kepler-11b, the innermost one, is about 11 times closer to its star than Earth is to the Sun (about 8.5 million miles versus 93 million miles). It is also the densest of the six exoplanets, at about 3.1 grams per cubic centimeter. It orbits the star in about 10 Earth days.

'¢    Kepler-11c and Kepler-11d are comparable in size to each other and have masses about 13.5 and 6.1 times that of Earth's mass, respectively. At 13.5 times the mass of Earth, Kepler-11c is the most massive of these six exoplanets.

'¢    Kepler-11e is the largest of the exoplanets, with a radius 4.52 times that of Earth and with a size comparable to the planets Uranus andr Neptune. It is also about half way between the parent star, Kepler-11, and the outermost exoplanet, Kepler-11g.

'¢    Kepler-11f has a mass 2.3 times that of Earth's, which makes it the one most similar to Earth's mass.

'¢    Kepler-11g is the outer most exoplanet, and is about 2 times closer to its star than Earth is to the Sun (about 43 million miles versus 93 million miles). It orbits the star in about 118 Earth days.

 

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