Suppose you arrived on the moon during a lunar eclipse. From your vantage point, looking back at earth, what astronomical event would you be witnessing?

The astronomical event that will be witnessed is a solar eclipse

Explanation:

A lunar eclipse occurs, the Sun is being shielded from the Moon by the Earth such that the Moon is in the shadow of the Earth.

Therefore, when there is a lunar eclipse here on Earth, then there is a solar eclipse being observed on the near side  (side closest to Earth) of the moon as the Earth is observed to be blocking the direct light from the Sun and the temperature on the surface of the moon will drop considerably as well as reduced visibility, due to the low light levels.

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