How to Watch a Solar or Lunar Eclipse: Everything You Need to Know
Four eclipses are on tap for 2022. Don't miss the chance to revel in the beauty and awe.
An eclipse is a celestial magic show. Abracadabra! The sun has a bite out of it. Presto! The moon turns red. It's a trick of light and shadow on a grand scale. Here's what you need to know about solar and lunar eclipses and how to witness these stunning cosmic events.
2022 eclipses
There are four eclipses on the schedule for this year: two partial solar eclipses (April 30 and Oct. 25) and two total lunar eclipses (May 15-16 and Nov. 7-8). During the partial eclipses, the sun will appear to have a dark bite taken out of its surface, but it won't plunge the landscape into an eerie darkness. The lunar eclipses will give the moon a reddish hue, so they're also known as "blood moons."
What's an eclipse?
Solar eclipses and lunar eclipses happen when one heavenly body throws a shadow on another.
An eclipse occurs when one cosmic object (like a moon) moves into the shadow of another (like a planet). Eclipses aren't just an Earth-related phenomenon. NASA's Curiosity rover gets treated to eclipses on Mars. But for our Earth-bound viewing purposes, eclipses here involve a combination of the sun, our planet and the moon.
Find an eclipse
Eclipses, especially total eclipses, can be rare viewing events thanks to the complex dance of orbits, timing and visibility. Remember the Great American total solar eclipse fever of 2017 in the US? The US will have to wait until 2024 for the next total eclipse of the sun. If you have the chance to catch any eclipse, be sure to take it.
NASA maintains a handy list of upcoming solar eclipses that includes the date, time, duration, type of eclipse and where it will be visible. The same site also hosts a table for lunar eclipses.
You might not have to miss an eclipse just because you're in the wrong geographic area. Observatories around the world often offer livestreams of big eclipse events. The Virtual Telescope Project also shares eclipse action when feasible.
Solar eclipses
A solar eclipse is like a cosmic photobomb. It happens when the moon gets in between us and the sun, throwing a shadow onto our planet and making it look like part or all of the sun has disappeared into darkness.
A total eclipse happens when the moon completely blocks out the sun. A partial eclipse is when the moon blocks just part of the sun's disk, taking just a bite out of the sun.
There are two parts to the moon's shadow, the penumbra and the umbra. People in the path of the penumbra see a partial eclipse. Those covered by the umbra are treated to a total eclipse. Check out this NASA illustration to see how it works. It's a good look at how only a small swath of the planet is in line to see the eclipse in person.
Notice the darker inner shadow (the umbra) in this NASA illustration from a video explaining the moon's role in a solar eclipse. The lighter outer shadow is the penumbra.
Eclipse vocabulary
Ring of fire. Annular eclipse. Diamond ring. Totality. You'll hear these phrases in connection with solar eclipses. Here's what they mean.
- Annular eclipse: This happens when the moon is at its farthest point from Earth and it doesn't appear large enough to completely blot out the sun during a solar eclipse.
- Diamond ring effect: This is the picturesque name given to the moments when the moon is no longer completely blocking the sun during a total solar eclipse. A small bit of the sun shines out over the edge of the moon, making it look like a celestial diamond ring with a glowing gem on one side.
- Ring of fire: This phenomenon is associated with an annular solar eclipse. The moon is too far away to block all of the sun, so sunlight leaks out all around it, creating a fiery ring that Johnny Cash would be impressed by.
- Totality: During a total eclipse, the time when the moon completely covers the sun is known as totality. If you're viewing this, the world around you darkens. This is the big moment that eclipse fans are waiting for. It lasts for only a brief amount of time and only a narrow stretch of the globe will be in the path of totality for any given solar eclipse.
Safe-viewing tips for solar eclipses
These eclipse glasses let you safely view the sun.
If you want to view a solar eclipse in person, you need to gear up. Never look directly at the sun.
The easiest way to get your eclipse fix is by using eclipse glasses, which are usually made from cardboard frames with solar filters for the lenses. Here are some tips from the 2017 solar eclipse on making sure your eclipse glasses are legit.
No eclipse glasses, no problem. Here's how to make a pinhole projector for viewing. You'll just need a cardboard box, a sheet of paper, aluminum foil and a few other common household items.
Lunar eclipses
The supermoon lunar eclipse as it moved over NASA's Glenn Research Center on Sept. 27, 2015.
The Earth's shadow is the culprit when it comes to a lunar eclipse. When our planet blocks the sun's light from reaching the moon, we get an eclipse. Bonus: You don't need special glasses to view a lunar eclipse. Instead of doing a disappearing act like the sun, the moon usually changes color during a total eclipse, picking up a reddish hue. This is sometimes referred to as a "blood moon."
NASA's explainer video talks about why the moon turns red (thanks to sunlight filtered through Earth's atmosphere) and why lunar eclipses don't happen more often (thanks to orbital paths).
As with solar eclipses, there are total and partial versions. A total lunar eclipse happens when the Earth is right in the middle, with the sun and the moon arranged on opposite sides. A partial eclipse happens when only some of the Earth's shadow falls on the moon.
In early June 2020, keen-eyed moon watchers saw a partial penumbral lunar eclipse. This is the most subtle of the bunch and happens when the moon moves through the Earth's outer (penumbral) shadow. It can trigger a very slight darkening of the moon, which can be hard to spot.
As with solar eclipses, witnessing a lunar eclipse in person is a matter of timing, geography and weather. Keep an eye on NASA's lunar eclipse page to see when and where future events are visible. They might not be as showy as a solar eclipse, but they can be just as magical.
Here's wishing you clear skies and many eclipses ahead.
