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Credit: McDonald observatory
The graphic shows the orbits of Kepler-18b, c, and d around their star compared to Mercury's orbit. The lower graphic shows the relative size of planets to their star and Earth to our Sun. |
Kepler Space Telescope hunting for exoplanets found three planets orbiting a star, Kepler-18, which is 10% larger than our Sun but has only 97% of solar mass. There are still planets yet to discovered in this system. What is special for this system is that the planets are in resonant orbiting path.
Those three planets are called Kepler-18b, c, and d. They orbit their star at very close range, even closer than Mercury which is the closest planet in our solar system. Kepler-18b uses only 3.5 days to orbit around the star. It is approximately 6.9 times Earth's mass and two times larger than our Earth. Thus, it is called "super-earth"