When Earth Hides the Moon

Written by Studio AM.

A lunar eclipse occurs when Earth moves between the Sun and the full Moon. The Moon passes into Earth's shadow. This alignment does not happen every month because the Moon's orbit is tilted compared with Earth's path around the Sun.

Earth's shadow has a lighter outer region called the penumbra and a darker central region called the umbra. If only part of the Moon enters the umbra, observers see a partial eclipse. If the whole Moon enters it, the eclipse is total.

During totality, the Moon often looks red or copper instead of disappearing. Sunlight passes through Earth's atmosphere before reaching the shadowed Moon. The atmosphere scatters much of the shorter blue light and bends some red light inward. Dust and clouds can change the exact color and darkness.

People on Earth's night side can watch a lunar eclipse without special eye protection. Unlike a solar eclipse, it does not require looking toward the bright Sun. The event makes the alignment visible: the curved edge of Earth's shadow crosses the Moon while filtered sunlight colors the darkness.

Questions

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  1. Question 1 of 4

    What is the main idea of the passage?

  2. Question 2 of 4

    Why does the Moon often look red during totality?

  3. Question 3 of 4

    What does “umbra” mean?

  4. Question 4 of 4

    Why does a lunar eclipse not occur every month?

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