The moon is the only natural satellite on the earth and the closest celestial body to us. Its average distance from the earth is about 384,406,5438+0 km. Its average diameter is about 3476km, slightly larger than the earth's diameter 1/4. The surface area of the moon is 38 million square kilometers, which is not as big as our Asia. The mass of the moon is about 735 billion tons, which is equivalent to the mass of the earth. The moon itself does not shine, but reflects sunlight. Its brightness varies with the angular distance between the sun and the moon and the distance between the earth and the moon. The average brightness at the full moon is-12.7, etc. The surface of the moon is a desert composed of plains, peaks and valleys. There are many craters formed by high-speed impact of space objects on the surface of the moon. There is no air to breathe on the moon, but there may be water to drink. Recently, ice was found at the bottom of a deep pit in the shadow of the moon. Scientists think that the ice may have been brought by a comet that collided with the moon. The ice of the comet did not melt because the temperature on the shadow of the moon was very low.