The “Blood Moon” was photographed in California in 2019
Today a rare “blood moon” was staged, a total lunar eclipse. In addition to lunar and solar eclipses, there are also stellar eclipses. What are the principles behind these astronomical phenomena?
A total lunar eclipse known as the “blood moon” will occur on November 8 in Asia, North America, Central America and Oceania.
According to NASA, the total lunar eclipse will last about an hour and a half.
Unlike a solar eclipse, a total lunar eclipse can be seen directly with the naked eye, without the need for professional telescopes or equipment. If you miss this total lunar eclipse, the next one will be in March 2025.
The astronomical phenomenon of the eclipse occurs when a celestial body enters the shadow of another celestial body.
Different phases of a lunar eclipse captured in 2010.
A lunar eclipse occurs when the earth moves between the sun and the moon, and the three are side by side.The moon is covered by the earth’s shadow (divided into shadow and penumbra) and cannot be directly illuminated by sunlight. In other words, what we see during a lunar eclipse is the shadow cast by the Earth on the lunar surface.
There are three different types of lunar eclipses when the moon moves to different shadow areas of the earth: total lunar eclipse, partial lunar eclipse, and penumbral lunar eclipse.
A total lunar eclipse occurs when the entire moon falls within the earth’s shadow. Some of the sunlight passes through the Earth’s atmosphere, filtering out most of the blue light, leaving only red light, giving the moon a copper-red color, known as the “blood moon”. Because the Earth is four times larger than the moon’s diameter and its shadow is wider, a lunar eclipse can last just over an hour.
A partial lunar eclipse occurs when part of the moon enters the earth’s shadow. Depending on the size of the eclipse, dark areas of the moon can turn a dull red, bronze, or charcoal gray due to the contrast between the shaded areas and the bright, shadow-unaffected lunar surface. Partial lunar eclipses occur at least twice a year.
A penumbral lunar eclipse occurs when the moon enters the terrestrial penumbra. Penumbral lunar eclipses are more difficult to distinguish with the naked eye: the smaller the part of the moon that enters the penumbra, the more difficult it is to observe, so this type of lunar eclipse is rarely mentioned.
Principles of a solar eclipse
As with a solar eclipse, when the moon passes between the sun and the earth, the sunlight is blocked by the moon. In other words, we will see the shadow cast by the moon on the earth’s surface.
Depending on how far the moon covers the sun, solar eclipses can also be divided into three categories: total solar eclipses, annular eclipses, and total annular eclipses.
The sun is 400 times wider than the moon, but also 400 times farther from the earth. When the sun, moon and earth are side by side, the moon’s shadow is large enough to block out the entire sun. Where a total solar eclipse occurs, in seconds or minutes, the sky becomes as dark as night.
When the moon is farther from earth, it appears to be “smaller” and cannot completely cover the solar disk, and the part of the sun that is not blocked by the moon appears ring-shaped, called the annular solar eclipse. An annular solar eclipse can last for more than ten minutes at most, but usually no more than five or six minutes. An annular solar eclipse will be seen in North and South America next October.
Total Annular Eclipse: Also known as a mixed solar eclipse, the moon has just reached the distance where it can completely cover the sun, forming a total solar eclipse, but then moves away from the earth and turns into an annular eclipse, or from one from an annular eclipse to a total eclipse. Total annular eclipses are quite rare, accounting for only 4% of all solar eclipses, the last time they occurred in 2013 and the next will be observed in Indonesia, Australia and Papua New Guinea on April 20, 2023.
eclipse
In addition to the sun and the moon, stars also experience stellar eclipses.
A binary star is a star system of two stars orbiting a common center of mass. Partial binary stars have orbits that adapt so well to the Earth’s plane that in parts of their orbits, one star passes in front of another star and blocks it, causing an eclipse.
