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What is an Eclipse?

An eclipse is a natural phenomenon that happens when one celestial object, like the moon or Earth, moves in front of another, causing a temporary shadow. The two most common types of eclipses are solar eclipses and lunar eclipses.

Types of Eclipses

a graphic demonstrating a solar eclipse where the moon is between the sun and the earth

Solar Eclipse

A solar eclipse is when the moon gets between the Earth and the sun. The moon covers the sun and casts its shadow on the Earth. Depending on how the moon covers the sun, we can have three types of solar eclipses:

  1. Total Solar Eclipse: The moon completely blocks the disk of the sun. You’ll see the solar corona, which is the glowing outer atmosphere of the sun, for a brief moment. These are rare and look incredible!
  2. Partial Solar Eclipse: The moon covers only part of the sun, leaving a “bite” out of the sun’s bright face.
  3. Annular Solar Eclipse: The moon covers the central part of the sun, but the outer edges remain visible, forming a bright ring or “annulus” around the moon.
  4. Hybrid Solar Eclipse: This is a rare type of eclipse. Sometimes it looks like a total eclipse, and other times like an annular eclipse, depending on your location on Earth.

a graphic demonstrating a lunar eclipse where the earth is between the sun and the moon

Lunar Eclipse

A lunar eclipse happens when the Earth comes between the sun and the moon, and it blocks the sunlight from reaching the moon. When this happens, the moon gets dimmed and sometimes looks red.

  1. Total Lunar Eclipse: The Earth comes between the sun and the moon, and its shadow covers the entire moon. The moon may turn reddish during this eclipse, often called a “Blood Moon.”
  2. Partial Lunar Eclipse: Only a part of the moon is covered by the Earth’s shadow. This makes a part of the moon look darker than usual.
  3. Penumbral Lunar Eclipse: The moon enters the Earth’s lighter outer shadow, called the penumbra. This makes the moon appear slightly dimmer but doesn’t change its color dramatically. It’s a subtle lunar event.

Upcoming Eclipses

Check back for more events.

Eye Safety

During a solar eclipse, it’s important to protect your eyes from the sun’s harmful rays. Looking directly at the sun, even during an eclipse, can seriously hurt your eyes and even cause permanent damage.

To keep your eyes safe, you must use special eclipse glasses or solar filters to safely watch a solar eclipse. These glasses have special lenses that block harmful light, allowing you to enjoy the eclipse without any worries. Remember, never use regular sunglasses or homemade filters for eclipse watching – only certified eclipse glasses or approved solar filters will keep your eyes out of harm’s way!

On the other hand, lunar eclipses are generally safe to watch with the naked eye.

Learn More

Students looking at the planet Earth being displayed in the planetarium

ASU Planetarium

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Educational Videos

Whether you’re a student, educator or just curious about the wonders of the universe, our videos unlock the mysteries of eclipses, explain proper eye safety and offer alternative methods of viewing eclipses.

Watch the videos

Educator Support and Resources 

If you’re an educator in need of lessons, engaging activities or assistance in planning an event centered around the captivating world of eclipses, don’t hesitate to get in touch with either Dr. Kenneth Carrell or our physics department. We’re here to provide you with the resources and support you need to create an educational and awe-inspiring experience for your students.

Explore the research guide, featuring valuable materials on eclipses, from the Porter Henderson Library.

Questions? Contact Us!

Department of Physics and Geosciences
Fax: 325-942-2188
ASU Station #10904, San Angelo, TX 76909
Associate Professor/Director of University Planetarium