Eclipse August 21

Eclipse August 21

Blog post by Dean
Wednesday, July 19, 2017


[Repost from October, 2016, with updates; APL does not have eclipse glasses, but we found them for sale at Lowe's!]

Do you know about the total solar eclipse coming next month? On August 21 the disk of the moon will block out the sun completely and throw a shadow on the earth that will track across the U.S. from sea to shining sea; diagonally from Oregon to South Carolina, like the satin sash on Miss America. (Watch an incredibly cool video of the shadow move across the country here: ECLIPSE2017.ORG.)

It might not be too late to find a hotel room. Austin is an easy distance; the closest the total darkness comes to Texas is just south of Nashville, Tennessee, not a bad drive. Travel a little farther and find the point of greatest eclipse near Hopkinsville, Kentucky, or the point of greatest duration near Murphysboro, Illinois. Though it sounds like those places would be great for viewing, the cognoscenti know that darkest and longest don't mean a thing if clouds roll in, and so they head for big-sky country east of the Cascades because that's a better bet for clear weather. Sometimes August in The South gets stormy… well, you live here; you know.

At most there will be just a bit more than two and a half minutes of totality, but before that happens, on the ground under the trees--on the surfaces around you--tiny sun crescents will appear. It sounds like science fiction, but it's true!  And then, when the moon blocks the whole sun, the sun's corona will shoot out from the edges of the shaded disk. It's the only safe time to look straight at the eclipse without a filter, and it's the only time to see the corona in visible light. 

It’s coincidence that we see total eclipses at all. The earth-moon-sun arrangement hasn’t always been such that the disk of the moon appears to completely cover the sun, and over time, the convergence will be disarranged again. We happen to exist in the happy era when all three bodies align.

If you're staying in town you'll see a partial eclipse in Austin. Use this ECLIPSE SIMULATOR to get a preview. You need eclipse glasses or a pinhole camera to view the sun. The glasses are inexpensive, available at Lowe's for $1.98 for the cardboard kind, $14.98 if you want a fancier model. They're easy to find online, too, and you still have time to order. 

The Howson Branch Library will hold an eclipse event. Here is a link to info: SOLAR ECLIPSE AFTERNOON at HOWSON. They'll be making pinhole viewers, but you can get a jump on the project here: INSTRUCTIONS for making a pinhole camera (from Jet Propulsion Laboratory). 

Austin will have a total eclipse of its own on April 8, 2024. Fredericksburg, Llano, Lampasas, Killeen, Waco, Dallas—anywhere along a swath from Laredo to Texarkana—will be great spots to see it near home, if it isn’t cloudy… in the spring… in Central Texas.

If you want to know what greatest duration and greatest eclipse mean, why the tiny crescents appear, what kind of filter to use to protect your eyes, if you want the global schedule of eclipses for the next century so you can fly your Lear Jet to Nova Scotia, here are books to explain everything eclipse, and travel books for the states through which the path of totality runs in 2017.

And here is an absolutely beautiful site from NASA. Your tax dollars at work!