Earth has a natural satellite called Moon that orbits the planet in 27.3 days.  The Moon is the fifth largest satellite in the Solar system, where the Sun is the only star.

The moon is the second brightest object in the sky after the Sun.  While the moon's surface is dark, it reflects the brightness of the Sun. 

The diameter of the moon is about 1/4 of Earth's diameter. The Moon's gravity is also about 1/6 of the gravitational pull of the Earth.  Because of its proximity to the Earth, the Moon's gravitational pull influences ocean tides on Earth. 

The Sun is about 400 times bigger than the Moon, but is 400 times farther.  This makes the Sun and Moon appear to be of the same size in the human eyes.

The average distance between the Earth and the moon is about 384,403 kilometers or 238,857 miles.  This distance is about 30 times the Earth's diameter. It would take light, which has a speed of 186,411.358 miles per second, only 1.2 seconds to travel from the Earth to the Moon.

As the moon revolves around the Earth at a slightly elliptical path, its proximity to the Earth also varies.  It is closest to the Earth, with a perigree distance of 363,104 kilometers or 225,622 miles and farthest with an apogee distance of 405,696 kilometers or 252,088 miles.  This means that the distance from Earth to Moon can vary by 43,592 kilometers, which makes the Moon appear bigger on certain nights.