What causes a lunar eclipse?

What causes a lunar eclipse?

• A. The Moon passes between the Sun and the Earth, blocking sunlight.
• B. A new planet aligns with Earth and Moon.
• C. The Sun blocks the Moon during the day.
• D. The Earth passes between the Sun and the Moon, casting a shadow on the Moon.

Answer: (D)

A lunar eclipse happens when the Earth lies directly between the Sun and the Moon, so Earth blocks sunlight from reaching the Moon and casts its shadow on it. This can only occur during a full Moon, when the Moon is opposite the Sun in the sky. If the Moon moves into Earth's umbra, we see a total lunar eclipse; if it only enters the outer shadow (the penumbra), it’s a penumbral eclipse; and if only part of the Moon enters the umbra, it’s a partial eclipse. The reddish glow seen sometimes during total eclipses comes from sunlight filtering through Earth’s atmosphere and bending into the shadow. The other descriptions describe scenarios that don’t cause a lunar eclipse: the Moon between the Sun and Earth would block sunlight from reaching Earth (a solar eclipse); aligning with a planet isn’t what creates the Earth’s shadow on the Moon; and the Sun blocking the Moon during the day would also be a solar eclipse, not a lunar one.

A lunar eclipse happens when the Earth lies directly between the Sun and the Moon, so Earth blocks sunlight from reaching the Moon and casts its shadow on it. This can only occur during a full Moon, when the Moon is opposite the Sun in the sky. If the Moon moves into Earth's umbra, we see a total lunar eclipse; if it only enters the outer shadow (the penumbra), it’s a penumbral eclipse; and if only part of the Moon enters the umbra, it’s a partial eclipse. The reddish glow seen sometimes during total eclipses comes from sunlight filtering through Earth’s atmosphere and bending into the shadow.

The other descriptions describe scenarios that don’t cause a lunar eclipse: the Moon between the Sun and Earth would block sunlight from reaching Earth (a solar eclipse); aligning with a planet isn’t what creates the Earth’s shadow on the Moon; and the Sun blocking the Moon during the day would also be a solar eclipse, not a lunar one.