About

Solar Eclipses

For thousands of years, humans have looked up at the sky and wondered about what they saw. Particular arrangements or alignments of heavenly objects were taken as signs or omens.

Perhaps one of the most awe-inspiring and influential celestial events to occur is a solar eclipse. Significant solar eclipses will be visible from the United States in 2023 and 2024. This tactile book highlights details surrounding the 2023 and 2024 eclipses but can be used to glean information about previous and future eclipses as well. Come and explore the world of eclipses with us!

Note: Tactiles are NOT to scale by distance and NOT to scale by size.

Tactile 1: Illustration of the alignment of the Sun, Moon and Earth that creates a total solar eclipse. Note that the Moon is found between the Earth and Sun. Also notice the labeled external tangent lines that define where the dark part of the moon’s shadow is located. This shadow is called the umbra.

Tactile 2: Illustration of five different stages of a total solar eclipse from the initial onset of the disc of the moon covering a portion of the sun to totality (center) and then back to partial.

Tactile 3: A map of the continental United States with the path of totality for the 2017 and 2024 total solar eclipses. It also shows the path of totality of the October 14, 2023 Annular Eclipse. Notice how one of the paths of totality overlaps the other 2, signifying it is the most recent one. Can you find it?

What is a solar eclipse?

A solar eclipse occurs when the sunlight reaching the earth is blocked by the moon. It is important to understand some basics of the orbits of the earth and moon. The earth orbits, or revolves, about the sun. It takes about 365 days for the earth to revolve once around the sun. The moon orbits, or revolves, around the earth and takes about 29 ½ days to revolve once around the earth with respect to the sun. As the moon orbits around the earth on nearly the same plane as the earth and sun; the moon is found between the earth and sun about every 29 ½ days (as shown on Tactile 1). When the moon is found there, it is called a “New Moon.” A solar eclipse only occurs during the New Moon phase.

How often do solar eclipses occur?

Various types of eclipses occur four to seven times a year with most years only having four. The type of eclipse being explored with this book is called a total solar eclipse and occurs somewhere on earth about every 18 months. Observers are rarely in the right position on earth (or within the path of totality, Tactile 1 and Tactile 3) to witness the entire disk of the sun being blocked by the disk of the moon (Tactile 2). In fact, if the observer were to stay in one place on earth, they would only be found in the path of totality about once every 400 years!

You might be wondering why an eclipse doesn’t occur every New Moon which occurs every 29 ½ days? The reason is that the orbital plane of the moon and earth is tilted by about 5° from the orbital plane of the earth and sun. This tilt causes the moon’s shadow to usually fall either above or below the earth.

How long do solar eclipses last?

Totality, or when the disk of the sun is entirely blocked by the disk of the moon (see Tactile 2), at any location along the “path of totality” can last up to eight minutes, though most of the time totality lasts on the order of two to three minutes. Totality for most of the United States on August 21, 2017 lasted over 2 minutes. For the upcoming annular eclipse on October, 14, 2023 it will last about 5 minutes; and, for the total solar eclipse on April 8, 2024 it will last about 4 minutes (depending on your specific location). However, from the start of the eclipse in which the sun is partially eclipsed by the moon until the end of the eclipse when the disk of the moon no longer blocks any of the sun takes a little over 2 hours (as shown on Tactile 2). For example, during the April 8, 2024 eclipse, the following locations will experience the eclipse during these timeframes:

North of San Antonio and west of Austin, Texas

• Partial starts about 12:16 pm local time and ends about 2:56 pm
• Totality starts about 1:33 pm local time and ends about 1:37 pm

Indianapolis, Indiana

• Partial starts about 1:51 pm local time and ends about 4:23 pm
• Totality starts about 3:06 pm local time and ends about 3:10 pm

Cleveland, Ohio

• Partial starts about 1:59 pm local time and ends about 4:29 pm
• Totality starts about 3:14 pm local time and ends about 3:18 pm

Buffalo, New York

• Partial starts about 2:05 pm local time and ends about 4:32 pm
• Totality starts about 3:18 pm local time and ends about 3:22 pm

North of Bangor, Maine

• Partial starts about 2:21 pm local time and ends about 4:40 pm
• Totality starts about 3:31 pm local time and ends about 3:35 pm

For complete details regarding specific times for specific locations across the United States and region check out https://solarsystem.nasa.gov/news/2332/new-nasa-map-details-2023-and-2024-solar-eclipses-in-the-us/

Although being in the path of totality and knowing specific times will make for a great experience, an observer should also pay attention to local weather forecasts to find a location within the path of totality where it will likely be clear skies!  For those not within the path of totality for either eclipse in the 48 continental states, you will still have an opportunity to witness a partially eclipsed sun.

Are solar eclipses dangerous to look at?

Yes!  It is never safe to look at the sun without proper means of viewing it. Be sure to wear eclipse glasses or other protective eyewear.

During a total solar eclipse, for people in the “path of totality,” the only time to safely look at the event is during totality when the disk of the sun is entirely obscured by the disk of the moon.  At this time, a layer of the sun’s atmosphere called the Corona is visible to the unaided/unprotected eye.  As the middle graphic in tactile 2 illustrates, the Corona can be seen radiating around the sun while the central disk remains black.  Normally, the photosphere of the sun’s atmosphere outshines the Corona.  It is interesting to note that the Corona can extend out over 4 million kilometers and can reach temperatures over 2 million degrees! Aside from the few minutes of totality, it is never safe to look directly at the sun.  Even an annular solar eclipse (as described in next section) can damage the eyes if it’s looked at directly without filters.  Again,  we note that it is never healthy to look directly at the sun and care should be taken to work with professionals who have some experience using proper methods of viewing eclipses of the sun. 

What’s the difference between a total solar eclipse, an annular eclipse, and a partial solar eclipse?

During a Total Solar Eclipse, the moon completely blocks the sun.  Even though the sun is about 400 times larger than the moon, the disk of each is about the same size in the sky as viewed from earth because of the distance each is from the earth.  Given that information, which one is farther away and which is closer?  Of course, Tactile 1 provides an answer, but be aware that Tactile 1 is NOT to scale by size and NOT to scale by distance.

The orbit of the moon around the earth is not a perfect circle but an ellipse.  Therefore, the moon is sometimes closer to the earth and sometimes farther from the earth.  If the moon is further from the earth during New Moon phase and is in the proper position for an eclipse to occur, the disk of the moon is not large enough as viewed from earth to cover the entire disk of the sun creating a ‘ring of fire’ where the outer edges of the sun are visible When this occurs it is called an Annular Eclipse.

As expected, during a Partial Solar Eclipse, the moon only partially blocks the sun.  Technically, a Partial Solar Eclipse means that no viewer on Earth can be in the right location to witness totality.  Practically speaking, however, the moon will “partially” block the sun for a large portion of Earth during a total solar eclipse or even an annular eclipse.  For example, during the October 14^th and April 8^th annular and total solar eclipses the entire United States including Hawaii and Alaska can witness a partial eclipse by using proper viewing precautions.  Tactile 3 outlines the contiguous United States and the specific paths of totality for the 2017, 2023 and 2024 eclipses. 

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Credit: NASA SSERVI Grants NNA14AB01A and NNA14AB05A