A moon is a natural satellite consisting of solid material that naturally orbits a planet or dwarf planet. Although the Earth has just one moon, there are other planets that have more, and some that even have none. Moons... More » Science Astronomy

No concrete evidence explains why there is a moon. The best hypothesis presented is the Giant Impactor hypothesis: It suggests that around 4.45 billion years ago, while the Earth was still forming, a large object hit the... More » Science Astronomy Our Moon

Venus is one of only two planets in the solar system to have no moons, the other being Mercury. As of 2014, there are 173 natural satellites known to be in orbit around planets in the solar system, mostly orbiting the ou... More » Science Astronomy Planets
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After Galileo built his first telescope in 1609, he observed and described the landscape of the moon, discovered four of the moons of Jupiter, discovered the phases of Venus, and discovered sunspots. Galileo's discovery ... More » Science Astronomy

The International Astronomical Union (IAU), an organization of astronomers, names the craters on planets and moons in the solar system by giving each planet a creative theme. For example, the moon’s craters are usually n... More » Science Astronomy

Although scientists use the term celestial body quite broadly, when they refer to a celestial body orbiting another body they are generally talking about natural satellites, or moons, orbiting a larger body such as a pla... More » Science Astronomy

The name of Earth's natural satellite is the moon. In terms of size, the moon is not the biggest natural satellite in the solar system, but it is large and ranks fifth among the other moons. In fact, the moon is one of t... More » Science Astronomy