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Lunar eclipse

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A lunar eclipse is a significant astronomical event that occurs when the Moon orbits through the shadow cast by Earth. This phenomenon is often referred to as a "blood moon" because the Moon frequently takes on a reddish hue. Unlike solar eclipses, which are brief and difficult to witness, lunar eclipses are much easier to observe. Anyone located on the night side of Earth can watch the event unfold. Furthermore, lunar eclipses are completely safe to view without any special eye protection.

The mechanics of an eclipse depend on the alignment of the Sun, Earth, and Moon. These events occur during specific periods known as eclipse seasons. During these times, the Moon's orbital plane is roughly in line with the Earth and the Sun. The specific type and duration of the eclipse are determined by how close the Moon is to the lunar node.

Geometry of a Lunar Eclipse
Geometry of a Lunar Eclipse

There are three primary types of lunar eclipses based on how much of the Moon enters Earth's shadow. A penumbral lunar eclipse occurs when the Moon enters the penumbra, which is the outer, lighter part of the shadow. In this stage, the Sun is only partially blocked, resulting in a subtle dimming of the lunar surface. About one-third of all lunar eclipses are penumbral. Only 3% of these are classified as total penumbral eclipses.

Eclipse lunar 2019
Eclipse lunar 2019

A partial lunar eclipse happens when the Moon lies partially inside the umbra. The umbra is the central, darkest region of the shadow where Earth totally shields direct sunlight. During a partial eclipse, the dark region looks much more distinct than a penumbral dimming. The Moon's average orbital speed is about 3,683 kilometers per hour. This speed means totality can last up to nearly 107 minutes. The entire process from first to last contact can last up to 236 minutes.

2007-03-03 - Lunar Eclipse small-43img
2007-03-03 - Lunar Eclipse small-43img

A total lunar eclipse occurs when the Moon's near side passes entirely into the Earth's umbral shadow. As the Moon enters this stage, the entire surface becomes more or less uniformly bright, allowing surrounding stars to become visible. The Moon does not turn completely dark because of the refraction of sunlight by Earth's atmosphere. This refraction bends light into the shadow cone. The reddish coloration is caused by Rayleigh scattering. This process removes high-wavelength colors like violet and blue from the light. Only the longer wavelengths, such as red, reach the Moon and reflect back to us.

Blood Moon
Blood Moon

The appearance of the Moon during totality can vary significantly. This variation is measured using the Danjon scale, which rates the darkness of the eclipse from L=0 to L=4. An L=0 eclipse is very dark, making the Moon almost invisible. An L=4 eclipse is a very bright copper-red or orange. The specific color depends on the amount of dust or clouds in Earth's atmosphere. For example, large volcanic eruptions can expel dust that makes the resulting red color much deeper.

Astronomers track the timing of these events using specific contact points. The process begins with P1, or first contact, when the penumbra touches the Moon's outer limb. This is followed by U1, when the umbra touches the Moon. U2 marks the beginning of the total eclipse when the Moon is entirely within the umbra. The peak of the event is called the greatest eclipse. Finally, the Moon exits the shadow through U3 and U4 contacts, ending with P4.

Lunar eclipse contact diagram
Lunar eclipse contact diagram

Historically, different cultures developed various myths to explain these celestial changes. The ancient Greeks used the curved shadow of the Earth during a lunar eclipse as evidence that the Earth is round. In contrast, the Incas and Mayans believed a jaguar was eating the Moon. In China, some traditions suggested a dragon was biting the Moon, leading people to ring bells to scare it away. Even the ancient Mesopotamians believed seven demons were attacking the Moon and the king.

Lunar eclipse symbol
Lunar eclipse symbol
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🖼️ Images & Media (10)
File:Lunar eclipse 04-15-2014 by R Jay GaBany.jpg
Lunar eclipse 04-15-2014 by R Jay GaBany.jpg
File:Geometry of a Lunar Eclipse.svg
Geometry of a Lunar Eclipse.svg
File:Eclipse_lunar_2019.gif
Eclipse_lunar_2019.gif
File:2007-03-03 - Lunar Eclipse small-43img.gif
2007-03-03 - Lunar Eclipse small-43img.gif
File:Lunar eclipse at sunrise Minneapolis October 2014.png
Lunar eclipse at sunrise Minneapolis...
File:Lunar eclipse contact diagram.svg
Lunar eclipse contact diagram.svg
File:Blood Moon.svg
Blood Moon.svg
File:Lunar eclipse symbol.svg
Lunar eclipse symbol.svg
File:Full Eclipse of the Moon as seen in from Irvine, CA, USA (52075715442) (cropped).jpg
Full Eclipse of the Moon as seen in from...
File:Eclipse from moon.jpg
Eclipse from moon.jpg
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