NASA's Kepler space observatory was launched on March 7, 2009. It cost 550 million dollars and was manufactured by Bell Aerospace And Technologies. It was named after the astronomer Johannes Kepler. Its mission was to find planets that are located in the area where life can exist, called the habitable zone.
The Kepler spacecraft data has recently discovered 715 new exoplanets, making it over 1,700 exoplanets that have been found. Exoplanets are planets outside of the solar system. Four of the planets are within the host star's habitable zone. These four planets are about four times the size of the Earth. The Kepler spacecraft's telescope took pictures of stars that were expected to have planets orbiting them for four years. It used the transit method of finding stars. This method can find planets when they are in front of their host star in the same reference frame as the Kepler telescope.
The Kepler spacecraft took pictures for four years. The 715 planets were discovered using only the first two years of the Kepler telescope's observations. It is predicted that many more exoplanets will be discovered using the last two years of its mission to find planets outside the solar system.
In 2013 two exoplanets were found that meet at least most of the requirements for life to exist on another planet. Kepler 62 is the name of the star that is 1,200 light years from the Earth. The star is only one-fifth as bright as the Sun of the Solar System. The planets were named Kepler 62-e and Kepler 62-f.
The exoplanet Kepler 62-e is located in the habitable zone and closest to the size of the Earth--only 60% larger. It is not known, however, if it has an atmosphere or if it is a rocky planet like the Earth. It orbits Kepler 62 every 122 days compared to 365 days for the Earth. This planet is expected to have a very cloudy sky. Kepler 62-f is farther from the host star Kepler 62, but it is only 40% larger than the Earth. This exoplanet takes 267 days to orbit its host star Kepler 62.
Both Kepler 62-e and Kepler 62-f are expected to be completely covered with water. Another planet that might support life was found orbiting the host star Kepler 69. This star is 2,700 light years away. The planet was named Kepler 69-c.
It is similar in size to the Earth. Another exoplanet named Kepler 62-b is twice the size of the Earth, but is not expected to be habitable because it is so hot.
The red dwarf star Gliese 581 is only about 20.6 light years from the Earth, only approximately one-sixtieth as far as Kepler 62. Two of the exoplanets orbiting the host star Gliese 581 are considered to be in the habitable zone. They were named Gliese 581g and Gliese 581d. Gliese 581g has one of the highest ratings for possibility of conditions for supporting life. It is probably between one and one half to two times the size of the Earth. Its mass is expected to be 3.1 times the mass of the Earth. It is estimated to be between 0.1 AU and 0.2 AU (Au is an abbreviation for the term astronomical unit that is a distance equal to 93 million miles, which is the distance from the Earth to the Sun ). The other planet Gliese 581d might be too cold because it is so far away from Gliese 581, but it might have a carbon rich atmosphere that could keep it warm.
An exoplanet with a mass 64.4 times that of the Earth and about 3.8 Au from the Earth was found orbiting its host star HD 10180. It was named HD 10180-h. Five planets were found closer to HD 10180 in the range 0.02 AU to 0.3 AU. The names and probable masses from closest to farthest are HD 10180-b mass 1.35 times the Earth, 10180-c mass 13.1 times the Earth, 10180-d mass 11.75 times the Earth, 10180-e mass 25.1 times the Earth.
Six exoplanets including aforementioned Gliese 581-g were discovered orbiting Gliese 581. Gliese 581-e is estimated about .02 AU from its host star and has an expected mass 1.7 times the Earth. The next two planets from nearest to farthest were named Gliese 581-b and Gliese 581-c. Their masses are 15.6 and 5.6 times the Earth's mass respectively. Both exoplanets are less than 0.1 AU from Gliese 581. The farthest two planets after Gliese 581-g are Gliese 581-d and Gliese 581-f. The expected masses and distances from the host star Gliese 581 are mass 5.6 times the Earth at approximately between 0.1 AU and 0.2 AU for Gliese 581-d and mass 7 times the Earth and between 0.7 AU and 0.8 AU for Gliese 581-f.