People used to believe the moon stayed in the same position, not rotating on its axis, because the side we see from Earth is always the same. The sum of the planets’ diameters is 380,016 kilometers. The average distance from Earth to the moon is 384,400 kilometers. “I didn’t believe it at first,” says Pizzetti, “but I took the diameter of each planet and added them.” Nice fitĪll the planets in our solar system can fit between Earth and the moon. NASA puts it this way: if Earth were the size of a nickel, the moon would be about as big as a coffee bean. The moon is less than a third of the width of Earth. The tidal bulge pushes the moon into a higher orbit, “like the faster, outside lanes of a test track,” according to the BBC. This causes the movement of the Earth’s oceans to form a tidal bulge. But the moon also exerts a gravitational force on the Earth. The moon is kept in orbit by the gravitational force that the Earth exerts on it. This is due to the gravitational effect of Earth’s tidal bulge, explains Andrealuna Pizzetti, a graduate student in the Clemson University Department of Physics and Astronomy. That’s the same rate at which our fingernails grow. The moon moves away from Earth about four centimeters each year. To commemorate the special occasion, here are some fascinating facts about Earth’s only natural satellite. National Moon Day is July 20, a celebration of the space flight, lunar landing and safe return of the Apollo 11 crew. As astronaut Neil Armstrong, commander of the Apollo 11 lunar mission, stepped onto the moon July 20, 1969, he uttered the famous phrase, “That’s one small step for man, one giant leap for mankind.”įifty-four years later, we know more about the moon than we know about any planet in our solar system (besides our own).

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