What Is An Eclipse?
An eclipse occurs when one celestial body, like a moon or planet, enters the shadow of another celestial object. Earth experiences two main types of eclipses: lunar and solar. Typically, when people refer to an "eclipse," they're talking about either a solar eclipse, where the Moon's shadow falls on the Earth, or a lunar eclipse, where the Moon ventures into the Earth's shadow. Still, the term can also describe events outside the Earth-Moon dynamic, such as a planet moving into its moon's shadow, a moon being enveloped by its planet's shadow or a moon entering the shadow of another moon.
If you're planning on viewing the much-anticipated 2024 total solar eclipse in the U.S.—or any upcoming solar eclipse—and you'd like to know more about what solar eclipses are, why they're so amazing, and how to view one, this info is for you. First, we'll cover solar eclipse basics. Then we'll take a deep dive into the 2024 total solar eclipse, including how to plan for the eclipse and how to view it safely.
What Is a Solar Eclipse?
The first fact to understand about solar eclipses is that they occur because of a remarkable cosmic coincidence: the Sun is just about the same apparent size in our sky as the Moon. While the Sun is actually about 400 times larger in diameter than the Moon, the Moon is also about 400 times closer than the Sun. Therefore, the Sun and the Moon appear to be about the same size in our sky.
This single fact explains why we see total solar eclipses - the Moon has an apparent size that just barely covers the Sun completely, yet is not too large that the Sun's atmosphere, its corona, is eclipsed as well. We on Earth occupy a celestial sweet spot to witness this sight.
If there are intelligent beings in other solar systems, the odds must be quite low that they would enjoy the same circumstances as we have on Earth. So we are the beneficiaries of a wonderful cosmic coincidence.
It was not always so. When the Moon first formed around our Earth over 4 billion years ago, it was much closer to the Earth and appeared much larger in our sky. So total solar eclipses in the early epochs of our Earth did block the Sun but also most of the corona. Over the eons, the Moon is gradually receding from the Earth due to the friction from the tides.
There are three types of solar eclipses:
The first is a total solar eclipse. A total solar eclipse is only visible from a small area on Earth. The people who see the total eclipse are in the center of the moon’s shadow when it hits Earth. The sky becomes very dark as if it were night. For a total eclipse to take place, the sun, moon, and Earth must be in a direct line. This amazing event (total solar eclipse) is what the United States will get to experience on April 8th, 2024. This total solar eclipse will be in a narrow path from Mexico to Eastern Canada. The path in the US goes from San Antonio, TX all the way up to Maine. This date can't get here soon enough!
The second type of solar eclipse is a partial solar eclipse. This happens when the sun, moon, and Earth are not exactly lined up. The sun appears to have a dark shadow on only a small part of its surface.
The third type is an annular solar eclipse. An annular eclipse happens when the moon is farthest from Earth. Because the moon is farther away from Earth, it seems smaller. It does not block the entire view of the sun. The moon in front of the sun looks like a dark disk on top of a larger sun-colored disk. This creates what looks like a ring around the moon. An annular solar eclipse will occur on October 14, 2023, and will be visible in parts of the United States, Mexico, and many countries in South and Central America. In the U.S., the annular solar eclipse begins in Oregon at 9:13 a.m. PDT and ends in Texas at 12:03 p.m. CDT.
During a solar eclipse, the moon casts two shadows on Earth. The first shadow is called the umbra (UM bruh). This shadow gets smaller as it reaches Earth. It is the dark center of the moon’s shadow. The second shadow is called the penumbra (pe NUM bruh). The penumbra gets larger as it reaches Earth. People standing in the penumbra will see a partial eclipse. People standing in the umbra will see a total eclipse.