NASA has discovered the eighth planet of a star system, similar to our solar system. The star, Kepler-90 is over 2,500 light years away and larger and hotter than our sun. It is the first star known to have as many planets as our solar system.
The Kepler-90 star system is much more compact than our solar system. The outermost planet orbits the star at about the same distance as the earth orbits the sun. its inner planets are small and rocky while the outer ones are larger and made up of gas.
The newly discovered planet, Kepler -90i, is the third celestial object in the star system. It is probably rocky and similar to our earth, but because of its closeness to its home star has an average surface temperature of about 400° C. It moves around the star once every 14.4 days.
The discovery was made based on data provided by the Kepler space telescope. Launched in March 2009, the telescope has constantly been scanning certain sections of the universe in search of new stars and planetary systems. Up to now, over 2,000 new worlds have been discovered.
Mercury is the first planet in the solar system, only about 60 million km away from the sun. It takes Mercury about 88 days to go round the sun once and one Mercury day is about 58 Earth days long. Mercury is a small planet - not much larger than our moon. Temperatures go up to 500 °C when it faces the sun and -150°C on its dark side.
The surface of Mercury is very much like that of the moon. Scientists believe that over 3 billion years ago, when the solar system was forming, the planet was constantly hit by asteroids and rocks . For its size, Mercury is a heavy planet. Gravity is about one third of the Earth's. The core of Mercury is probably still liquid.
Mercury is the first planet in the solar system, only about 60 million km away from the sun. It takes Mercury about 88 days to go round the sun once and one Mercury day is about 58 Earth days long. Mercury is a small planet - not much larger than our moon. Temperatures go up to 500 °C when it faces the sun and -150°C on its dark side.
The surface of Mercury is very much like that of the moon. Scientists believe that over 3 billion years ago, when the solar system was forming, the planet was constantly hit by asteroids and rocks . For its size, Mercury is a heavy planet. Gravity is about one third of the Earth's. The core of Mercury is probably still liquid.
The idea that life could, or even does, exist on Mars has a long history. In 1877 the Italian astronomer Schiaparelli said he saw a system of canals all over Mars. But close-up pictures from Mars have shown that no such canals exist. The early Viking spaceships that landed on Mars in 1976 proved that there is no organic material on the planet.
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