Lunar eclipses occur when Earth’s shadow blocks the sun’s light, which otherwise reflects off the moon. There are three types — total, partial and penumbral — with the most dramatic being a total lunar eclipse, in which Earth’s shadow completely covers the moon.
A total lunar eclipse has the direct sunlight completely blocked by the earth’s shadow. The only light seen is refracted through the earth’s shadow. This light looks red for the same reason that the sunset looks red, due to rayleigh scattering of the more blue light. Because of its reddish color, a total lunar eclipse is sometimes called a blood moon.
The Moon Looks Red
Even though the Earth completely blocks sunlight from directly reaching the surface of the Moon, the Moon is still visible to the naked eye during a Total Lunar Eclipse. This is because the Earth’s atmosphere refracts sunlight and indirectly lights up the Moon’s surface.
Full Moon and Total Lunar Eclipses
Why don’t we see a lunar eclipse every month if a full Moon is needed for a Total Lunar Eclipse?
This is because the plane of the Moon’s orbital path around the Earth is inclined at an angle of 5° to the Earth’s orbital plane, also known as the ecliptic, around the Sun.
Today Lunar Eclipse
The last lunar eclipse was on Sept. 27, 2015.
Here is a schedule of upcoming lunar eclipses:
- July 27, 2018: Penumbral eclipse. Visible from Asia, Australia, Pacific Ocean, western Americas.
- Sept. 16, 2016: Penumbral eclipse. Visible from Europe, Africa, Asia, Australia, western Pacific Ocean.
Eclipses in Different Colors
A lunar eclipse can also be yellow, orange, or brown in color. This is because different types of dust particles and clouds in the Earth’s atmosphere allow different wavelengths to reach the surface of the Moon.
Seven Stages of the Eclipse
- Penumbral eclipse begins: This begins when the penumbral part of Earth’s shadow starts moving over the Moon. This phase is not easily seen by the naked eye.
- Partial eclipse begins: The Earth’s umbra starts covering the Moon, making the eclipse more visible.
- Total eclipse begins: Earth’s umbra completely covers the Moon and the Moon is red, brown or yellow in color.
- Maximum eclipse: This is the middle of the total eclipse.
- Total eclipse ends: At this stage, the Earth’s umbra starts moving away from the Moon’s surface.
- Partial eclipse ends: The Earth’s umbra completely leaves the Moon’s surface.
- Penumbral eclipse ends: At this point the eclipse ends and the Earth’s shadow completely moves away from the Moon.
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