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What is an Eclipse?
April 3, 2024 at 11:17 AM EDT
By WeatherBug Meteorologist, Kayla St. Germain
A total solar eclipse is coming April 8th, 2024, but what is a solar eclipse?
What is an Eclipse?
Before we divulge into the astronomical phenomenon of an eclipse, let’s discuss the relationship between our Moon and Earth. Looking up at the night sky the Moon appears to wax and wane through the month. This is what we call the phases of the Moon. These phases are a visual representation of the Moon travelling around the Earth. There are 9 distinct phases, but for brevity we are only going to focus on 2, full and new. A Full Moon is when the Sun illuminates the entire Moon. This is only possible when the Earth is in between the Moon and Sun. In other words, when the Moon is in the Earth’s shadow. A New Moon is when the Moon looks invisible. This is because the Moon is now in between the Earth and Sun. In other words, the Earth is in the Moon’s shadow.
An eclipse is when a celestial body moves into the shadow of another. If that is the case, you might be asking why eclipses don’t happen twice a month. Recall that the Moon travels around the Earth; we call this an orbit. The Moon’s orbit is not a perfect circle, it is elliptical. In addition, it doesn’t orbit the Earth on a level plane. This plane is slightly tilted by 5 degrees. This small incline is the reason why an eclipse doesn’t occur with every Full and New Moon. The Earth, Moon, and Sun need to align in order for a partial or full eclipse.
What is a Lunar Eclipse?
A lunar eclipse occurs when a Full Moon moves into Earth’s shadow. During this event, the Moon turns red because Earth’s atmosphere filters out the blue light. There are two types of lunar eclipses, total and partial. A total lunar eclipse occurs when the Earth, Moon, and Sun are completely aligned. Such occurrences are rare, which is why total lunar eclipses are every 2.5 years on average. A partial lunar eclipse is when the Earth, Moon, and Sun are not fully aligned. Partial lunar eclipses are not as rare, occurring at least twice a year. Lunar eclipses are safe to look at, special glasses are not required for protection.
What is a Solar Eclipse?
A solar eclipse can only occur during a New Moon as the Earth moves into its shadow. There are three types of solar eclipses: total, partial, and annular. We already discussed the difference between a total and partial eclipse. What is an annular solar eclipse? Recall that the Moon’s orbit is elliptical. As a result, there is a point when the Moon is farthest from Earth. An annular solar eclipse occurs when a New Moon is at its farthest from Earth. This type of solar eclipse does not completely obscure the Sun because the Moon appears smaller. This gives the Moon a halo-like appearance for a few minutes.
During a solar eclipse, the Moon casts two shadows on Earth, umbra and penumbra. The umbra shadow is the darkest and gets smaller as it approaches Earth. People in the path of the umbra will see a total eclipse. In addition, during a total solar eclipse, the sky briefly gets dark, like it was night. The penumbra is a lighter shadow that grows as it approaches Earth. Folks standing in the penumbra will only see a partial solar eclipse. Unlike a lunar eclipse, a solar eclipse requires special glasses, not sunglasses.
Source: NASA
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Image: Colin Behrens from Pixabay
What is an Eclipse?
Before we divulge into the astronomical phenomenon of an eclipse, let’s discuss the relationship between our Moon and Earth. Looking up at the night sky the Moon appears to wax and wane through the month. This is what we call the phases of the Moon. These phases are a visual representation of the Moon travelling around the Earth. There are 9 distinct phases, but for brevity we are only going to focus on 2, full and new. A Full Moon is when the Sun illuminates the entire Moon. This is only possible when the Earth is in between the Moon and Sun. In other words, when the Moon is in the Earth’s shadow. A New Moon is when the Moon looks invisible. This is because the Moon is now in between the Earth and Sun. In other words, the Earth is in the Moon’s shadow.
An eclipse is when a celestial body moves into the shadow of another. If that is the case, you might be asking why eclipses don’t happen twice a month. Recall that the Moon travels around the Earth; we call this an orbit. The Moon’s orbit is not a perfect circle, it is elliptical. In addition, it doesn’t orbit the Earth on a level plane. This plane is slightly tilted by 5 degrees. This small incline is the reason why an eclipse doesn’t occur with every Full and New Moon. The Earth, Moon, and Sun need to align in order for a partial or full eclipse.
What is a Lunar Eclipse?
A lunar eclipse occurs when a Full Moon moves into Earth’s shadow. During this event, the Moon turns red because Earth’s atmosphere filters out the blue light. There are two types of lunar eclipses, total and partial. A total lunar eclipse occurs when the Earth, Moon, and Sun are completely aligned. Such occurrences are rare, which is why total lunar eclipses are every 2.5 years on average. A partial lunar eclipse is when the Earth, Moon, and Sun are not fully aligned. Partial lunar eclipses are not as rare, occurring at least twice a year. Lunar eclipses are safe to look at, special glasses are not required for protection.
What is a Solar Eclipse?
A solar eclipse can only occur during a New Moon as the Earth moves into its shadow. There are three types of solar eclipses: total, partial, and annular. We already discussed the difference between a total and partial eclipse. What is an annular solar eclipse? Recall that the Moon’s orbit is elliptical. As a result, there is a point when the Moon is farthest from Earth. An annular solar eclipse occurs when a New Moon is at its farthest from Earth. This type of solar eclipse does not completely obscure the Sun because the Moon appears smaller. This gives the Moon a halo-like appearance for a few minutes.
During a solar eclipse, the Moon casts two shadows on Earth, umbra and penumbra. The umbra shadow is the darkest and gets smaller as it approaches Earth. People in the path of the umbra will see a total eclipse. In addition, during a total solar eclipse, the sky briefly gets dark, like it was night. The penumbra is a lighter shadow that grows as it approaches Earth. Folks standing in the penumbra will only see a partial solar eclipse. Unlike a lunar eclipse, a solar eclipse requires special glasses, not sunglasses.
Source: NASA
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Image: Colin Behrens from Pixabay