Everything you need to know before the solar eclipse
• • • Having your own eclipse party? Download our activity sheet here! • • •
Here in the United States we have total solar eclipse fever — that’s because on Monday, August 21, a total solar eclipse will be visible on a path from Oregon on the west coast to South Carolina on the east coast. And the rest of the country will get a glimpse at a partial eclipse. This is the first solar eclipse to go across the US since 1979.
(Wondering how much of the eclipse you’ll be able to see? Find out here.)
How to view the eclipse safely
As cool as a solar eclipse is, you cannot just go out and stare at the sky. Nope. Please don’t. Really. Don’t do it.
Our eyes are made to take in light, but not this much light. The sun is really, really, really bright. It’s so bright, that regular sunglasses won’t do you any good if you’re staring right at it. Normal sunglasses block 80-85 percent of visible light. But there is so much visible light coming from the sun that in order to not damage the cells in your eyes, you need to block out 99.9996 percent of it.
In order to do that, you’ll need special eclipse viewing glasses. You can order them online or see if your local public library will be giving them out.
But don’t worry! If you don’t have special glasses, you can still observe the eclipse. You can make a pinhole projector out of cardboard, or simply a piece of paper. You can find instructions here.
You can also just use your hands, or a colander or the shadows made by trees! Another fun idea suggested by NASA scientist William Dean Pensell is to spell your name using a series of small holes in a piece of cardboard and then you can see your name spelled out in tiny solar eclipses on the ground!
But even if you don’t have eye protection that will allow you to look directly at the sun, you can just go outside and look at the world around you. There’s some cool stuff that will happen.
An observation checklist:
• What’s happening with the weather? A breeze might pick up during totality because the air cools down significantly.
• What’s happening with plants and animals? You might see flowers close up, or birds start to roost as if they’re getting ready to go to sleep.
• What does the light feel like? The quality of shadows and light will change as the sun gets obscured.
Chasing the eclipse
Find out why some NASA scientists are taking the sky to chase the eclipse.
What’s happening during an eclipse?
A total solar eclipse happens when our view of the sun is blocked by the moon. This happens when the earth, the moon and the sun are perfectly aligned. The fun, astronomical term for this alignment is: syzygy. Lunar eclipses are also syzygys, as are the full moon and new moon.
The earth is constantly orbiting around the sun and the moon is constantly orbiting around the earth. Even though these orbits have different lengths the times of the syzygys can be predicted.
A solar eclipse starts out slow and hopefully it happens on a clear, sunny day where there are no clouds to get in the way of your eclipse viewing.
The sun starts as a nice big circle, then a small bite is taken out. After this initial nibble, the moon starts to cover more and more of the solar disk, until all that’s left is a crescent. It can take over an hour to reach this point. The sky is pretty dark now.
And then things start to happen faster. As totality approaches, only a few spots of the sun’s light peek through. These are called Baily’s beads. What’s happening is we’re catching a glimpse of the sun seen through the low-lying valleys on the moon’s surface.
Then there’s a bright flash of light. This is known as the diamond ring effect. And it means totality will begin in a few seconds.
Then it begins. Totality. The sun has been completely covered by the moon. The sky has darkened. The corona of the sun — the outer layer of the sun’s atmosphere — suddenly becomes visible. It lookslike wisps or plumes of light coming off the dark circle, where the sun used to be. This total eclipse will last a couple of stunning minutes before the sun starts to be revealed again.
A crescent of the sun will be visible, and the sky will grow lighter as the moon continues its transit out of the sun’s way.
Pretty cool, right?
If you won’t be in the US for this solar eclipse, there are plenty more coming up: In 2019 and 2020 a total solar eclipse will be visible in Chile and Argentina. In 2024, Mexico, US and Canada will get the treat. In 2026, it will be Greenland, Iceland and Spain’s turn. 2027 brings the phenomenon to Morocco, Spain, Libya, Saudi Arabia, Algeria, Egypt Yemen, and Somalia. And 2028 will bring the show to Australia and New Zealand.
P.S. This episode’s Moment of Um answers the question: Why are bugs attracted to light? Listen using the audio player at the top of the page!