Emerald Robinson: Hi! I am Emerald Robinson. In this What Is Video we will take a look at the Earth's only natural satellite, the moon.
The moon is called the moon simply because nobody knew that any other moon existed until Galileo discovered Jupiter's moons in 1610. The moon is the fifth largest planetary satellite in the solar system, with a diameter of 2,159 miles; it's roughly one-fourth the diameter of Earth.
The moon's gravity is one-sixth of Earth, so if you weigh 120 pounds on Earth, you would only weigh 20 pounds on the moon. The moon is nearly 239,000 miles away, close enough that its gravitational force influences the Earth's tides.
The moon rotates on its axis once for every orbit it makes around the Earth, every 27.
3 days. This means the same side of the moon always faces the Earth. The moon possesses a crust, mantel, and core. It has no atmosphere, which means it has no weather or wind to cause erosion. Therefore, all the footprints left by the manned missions to the moon, beginning with Neil Armstrong's first steps on July, 26th 1969, are still there. The only thing that could destroy them is a falling meteorite. Craters caused by impacts cover the landscape of the moon, but the dark solid areas of the moon are flat region of cooled lava from volcanic activity that stopped about 1.
2 billion years ago. Those areas called Maria cover 16% of the moon.
Earth's moon is widely believed to have formed when a Mars-sized object collided with the Earth over 4.
5 billion years ago. The impact was so catastrophic that debris was kicked into orbit around Earth, which led to the formation of the moon.
The moon is the only object man has ever visited beyond Earth.