Galaxy's

All objects in the Galaxy revolve around the Galaxy's center.

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The Hubble Constant defines the relationship between a galaxy's distance from the Earth and the speed with which the galaxy is moving away from the Earth.

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Scientists at the Harvard-Smithsonian Center for Astrophysics, after analyzing data from NASA's Kepler space telescope, calculated that six percent of the galaxy's 75 billion red dwarf stars have potentially habitable, Earth-sized planets. Red dwarfs — which are smaller, cooler and much dimmer than our own Sun — are the most common stars in the galaxy, so the closest Earth-like planet could be just 13 light years away, the astronomers conclude in their new study.

Source: tatoeba (12158646)