# Which speed is greater: the lunar shadow on the surface of the Earth during a solar eclipse or the earth’s shadow on the surface

Which speed is greater: the lunar shadow on the surface of the Earth during a solar eclipse or the earth’s shadow on the surface of the Moon during a lunar eclipse?

The speed of motion of the lunar shadow on the surface of the Earth is equal to the difference between the orbital speed of the Moon (1 km / s) and the linear speed of a point on the Earth’s surface (at the equator, 0.5 km / s), i.e., this difference is 0.5 km / s. The speed of movement of the earth’s shadow on the surface of the Moon will be equal to the difference between the orbital speed of the Earth in the frame of reference associated with the Moon (1 km / s) and the linear speed of a point on the lunar surface (at the equator of the Moon about 0.1 km / s), i.e. 0-9 km / s. Thus, the earth’s shadow on the surface of the moon moves about twice as fast as the moon’s shadow on the surface of the earth.

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