One of the many differences between the Earth and the moon is simply that the Earth is a planet and the moon orbits the Earth as its satellite. The Earth's circumference is 24,873.6 miles, while that of the moon is 6783.... More »

The main way the moon affects the Earth is the tides. The moon plays an important role in protecting the Earth from space rocks, such as meteorites. More subtle effects of the moon include minor effects on climate, the h... More »

The moon orbits the earth due to gravity. This gravitational force of attraction between Earth and the moon provides the necessary centripetal force to keep it in a circular orbit around Earth. More »

Earth has many satellites orbiting it, but the only significant natural satellite that orbits the Earth is the moon. The Union of Concerned Scientists (UCS) maintains a listing of all man-made satellites orbiting the Ear... More »

The moon orbits Earth about once every 27.322 days. Viewed from Earth, the moon's orbit is nearly a perfect circle tilted approximately 5 degrees to Earth's orbit. Due to tidal forces, the same side of the moon always fa... More » Science Astronomy Our Moon

Moon phases occur because the angle of the Earth, moon and sun changes as the moon orbits the Earth. One-half of the moon is always illuminated by the sun. As a person's angle of sight changes, different portions of sunl... More » Science Astronomy Our Moon

The moon orbits around the Earth on a 29 day cycle. Half of the moon is always lit by the sun's rays but different amounts of this illumination can be seen from Earth depending on the angle the moon makes with the sun re... More » Science Astronomy Our Moon