Lunar Eclipse 101 | National Geographic

Summary

A lunar eclipse occurs when the Earth blocks sunlight from reaching the Moon during a full moon, which happens every 29.5 days. Due to the Moon's tilted orbit, eclipses don't happen monthly. There are three types: total, partial, and penumbral. Total eclipses cast a reddish glow on the Moon due to Earth's atmospheric refraction. Lunar eclipses can be observed from the night side of Earth and are safe to view with the naked eye. As the Moon slowly moves away from Earth, future total lunar eclipses may become less frequent.

Takeaways

• 🌕 A lunar eclipse occurs when the Earth blocks some or all of the Sun's direct light from reaching the Moon.
• 🌒 Lunar eclipses only happen during a full moon, which occurs approximately every 29.5 days.
• 🌎 The Moon's orbit is tilted, preventing a lunar eclipse from happening every month.
• 🌗 There are two types of Earth's shadows: the larger penumbra and the smaller, darker umbra.
• 🌑 There are three types of lunar eclipses: total, partial, and penumbral.
• 🔴 A total lunar eclipse gives the Moon a sunset red color due to the refraction of red light by Earth's atmosphere.
• 🌑 A partial lunar eclipse happens when only part of the Moon passes into the Earth's umbral shadow.
• 🌘 A penumbral lunar eclipse is subtle and causes the Moon to appear slightly darker than normal.
• 🌌 Lunar eclipses can be observed from the entire nighttime half of the Earth and are safe to view with the naked eye.
• 🌙 The Moon is gradually moving away from Earth, and in the distant future, it may no longer be close enough for total lunar eclipses to occur.

Q & A

What is a lunar eclipse?

A lunar eclipse occurs when the Earth blocks some or all of the sun's direct light from reaching the moon.

Why does a lunar eclipse only happen during a full moon?

A lunar eclipse happens during a full moon because that's when the moon is on the opposite side of the Earth from the sun, allowing the Earth to cast a shadow on the moon.

Why don't we have a lunar eclipse every month?

We don't have a lunar eclipse every month because the moon's orbit is tilted a few degrees relative to the Earth, so the Earth, moon, and sun don't always align perfectly.

What are the two types of shadows the Earth casts on the moon during an eclipse?

The Earth casts two types of shadows on the moon during an eclipse: the penumbra, which is a larger shadow, and the umbra, which is a smaller, darker shadow.

What is the difference between a total lunar eclipse and a partial lunar eclipse?

In a total lunar eclipse, the moon falls entirely within the Earth's umbral shadow, while in a partial lunar eclipse, only part of the moon passes into the umbra.

Why does the moon appear red during a total lunar eclipse?

During a total lunar eclipse, the moon appears red because the Earth's atmosphere scatters shorter blue wavelengths of light and refracts longer red wavelengths toward the moon.

How does volcanic activity affect the color of the moon during a total lunar eclipse?

Volcanic activity can block out enough light to render the moon a darker red or even near black during a total lunar eclipse due to the ash in the atmosphere.

What is a penumbral lunar eclipse and why is it less noticeable?

A penumbral lunar eclipse occurs when the moon passes through the Earth's penumbral shadow, and it is less noticeable because the moon appears only slightly darker than normal.

How often can lunar eclipses occur in a year?

Lunar eclipses can occur up to three times a year.

Is it safe to look at the moon with the naked eye during a lunar eclipse?

Yes, it is safe to look at the moon with the naked eye during a lunar eclipse, unlike a solar eclipse.

Why will lunar eclipses eventually become impossible to witness?

Lunar eclipses will eventually become impossible to witness because the moon is inching away from the Earth each year, and billions of years from now, it will be too far away to fall completely within the Earth's umbral shadow.