Causes and Occurrences of Total Solar Eclipses

People travel thousands of miles to see a solar eclipse. There’s nothing like darkness falling and the excitement ripple through the crowd. A total solar eclipse will soon grace the skies in parts of Central America and North America, and some places outside the total path will be able to see a partial solar eclipse. So now is the perfect time to ask what exactly a solar eclipse is.

When one celestial object is hidden from view by another celestial object moving between them, astronomers call the event an “occultation.” Strictly speaking, a total solar eclipse is the occultation of the sun by the moon.

A total solar eclipse occurs when the moon and sun line up perfectly, with the moon moving in front of the sun and blocking nearly all of the sun’s light. From the path of totality, or the area of ​​the Earth where a total solar eclipse is visible, the sun almost disappears. This part of the eclipse can last up to 7.5 minutes. The solar eclipse on April 8th will last 4 minutes and 27 seconds.

What causes solar eclipses?

There are many different types of solar eclipses, but all occur when the moon passes in front of the sun, blocking some or all of the light seen from certain parts of the Earth. By pure cosmic coincidence, the moon is about 400 times smaller than the sun, but the sun is about 400 times farther away, so the moon and sun appear to be the same size in the sky. When the two line up perfectly during the new moon phase, when the moon is between the Earth and the sun, the moon can block all of the sun’s light. This is a total solar eclipse.

During a solar eclipse, the moon casts two shadows. The central part of the shadow where light does not reach is called the umbra. The outer partial shadow is known as the penumbra. Only light coming from part of the sun’s disk can reach here. During a total solar eclipse, the path of totality is land within the umbra. On April 8, the road will be 185 kilometers wide and will cross North America from Mexico through the United States and Canada. However, the total path can be as narrow as 150 kilometers. The penumbra covers a much larger area and a partial solar eclipse can be seen in those locations.

What types of solar eclipses are there?

A partial solar eclipse occurs when the moon blocks only part of the sun’s light. This occurs when the viewer is within the penumbra. Before and after totality, you can see the moon slowly eclipsing the sun in a partial solar eclipse. However, because the moon’s central shadow completely misses the Earth, only a partial solar eclipse may be visible from anywhere on Earth.

An annular solar eclipse occurs when the moon’s elliptical orbit moves it farther from Earth than normal, blocking most of the sun’s light but leaving behind a so-called ring of fire. A hybrid solar eclipse occurs when some parts of the world see a total solar eclipse, while other parts see an annular solar eclipse. Total solar eclipses, hybrid solar eclipses, and annular solar eclipses are all types of “central” solar eclipses, meaning that the umbra is projected somewhere on Earth.

Solar eclipse in 2024

On April 8th, a total solar eclipse will pass over Mexico, the United States, and Canada. Our special series covers everything you need to know, from how and when to see a solar eclipse to the strangest solar eclipse experience of all time.

How often do solar eclipses occur?

Every year, anywhere from two to five solar eclipses are visible somewhere around the world. A total solar eclipse occurs on average every 18 months. However, in certain locations on Earth, the portion of the Earth where a total solar eclipse is visible is so small that a total solar eclipse is only seen about once every 400 years.

What is a lunar eclipse?

A lunar eclipse occurs when the moon moves through the shadow that Earth casts in space. These events always occur during a full moon when the moon is on the opposite side of Earth’s sun. But they don’t happen every full moon because our moon’s orbit is tilted around the Earth compared to Earth’s orbit around the sun.

Do solar eclipses always occur in pairs?

A solar eclipse occurs when the Earth, Sun, and Moon line up (a so-called syzygation), so a solar eclipse is always accompanied by a lunar eclipse two weeks before and after it. This year, a lunar eclipse will occur on March 24th, two weeks before the solar eclipse on April 8th. However, it will be a penumbral lunar eclipse, meaning only the Earth’s outer shadow will hide the moon.