Wednesday, June 28, 2017

What are you doing August 21, 2017?

If you live in the United States and your answer is anything other than "watching the total solar eclipse," I'm gonna say you need to change your plans.

Here's why this whole thing is so awesome.

First of all, it's a cosmic coincidence that total solar eclipses happen AT ALL. Our sun just happens to be 400 times bigger than the moon, but it also just happens to be 400 times farther away from us. So from our point of view on earth, they appear to be exactly the same size. The moon passes between the sun and the earth, causing a total solar eclipse, fairly often...it's visible from some point on earth about once every 18 months. But the path of totality crossing the United States? That's a little rarer. The last time it happened was in 1979, and it won't happen again until 2024.

So where's it gonna be visible? HERE:


That grey band is where you gotta be to see totality. You'll still get a pretty good show elsewhere (check out this guy's site for more info), but it's less than a day's drive to get to the path of totality from just about any point in the U.S. So I say go for it! Carpe diem, people!

Although...two warnings. Number one, don't look at the eclipse without eye protection. You can suffer serious permanent eye damage from looking directly at the sun, even when it's partially blocked by the moon. You can get special "eclipse glasses" for hella cheap on Amazon, though (pack of ten for $10). Regular sunglasses won't cut it. Number two, hotels and campsites along the path of totality are BOOKED SOLID, and have been for months. Because big space nerds like me plan their entire year around this.

BUT JUST CHECK OUT WHAT WE HAVE TO LOOK FORWARD TO!
Here's what will happen in the path of totality on August 21st, 2017, over the course of about half an hour. (DON'T FORGET TO WEAR ECLIPSE GLASSES!)

First Contact
As the moon starts to move in front of the sun, it will appear to take a little tiny bite out of it. You'll be able to see this with a telescope before you can see it with the naked eye.

Crescent projections may possibly be seen on various surfaces
As more of the sun is covered, it will look like a crescent. If you happen to be near some trees or other vegetation, look on the ground. The spaces between the leaves create a "pinhole camera," projecting images of the solar eclipse on the ground. You can also create this same effect by making your own pinhole projector--just punch a tiny hole in a sheet of paper or cardboard.

Changing light
The light will become noticeably dimmer. You may even notice a strange or eerie "tint" to the light as more of the sun is blocked, and colors will appear washed out.

Strange animal behavior
If you happen to be near wildlife, you may notice some changes in behavior. Animals don't keep calendars of solar eclipses (that we know of), so they interpret the darkening light as oncoming twilight, and may either settle in for the night, or get up and start their nocturnal activities. (Joke's on you, fauna!)

Sharpening shadows
Because of the angle and amount of light, shadows become much sharper. If you look at your own shadow, you may be able to see the shadows of the individual hairs on your arms.

Drop in temperature
Two thirds of the sun's radiation is in the form of heat, so as more of the sun is covered, we get less of that heat. The weather changes will vary depending on where you are, but you can expect an average drop in temperature of about 10 degrees Fahrenheit.

Oncoming umbral shadow
Quick! Look to the west! You'll see the moon's shadow barreling towards you as the eclipse continues. The shadow moves across the landscape at over 1000 mph! (By comparison, planes cruise at around 575 mph, and the speed of sound is about 767 mph.)

Shadow bands
Just before totality, you may be able to see shadow bands rippling across any white-colored surfaces nearby. The tiny sliver of sunlight remaining passes through layers of turbulent air in the earth's atmosphere, producing shadow bands--kind of like the patterns the sunlight makes in water.

Bailey's beads
The moon isn't a perfect sphere...it's got mountains and valleys just like earth. As it passes in front of the sun, a few last shafts of light pass through these valleys, creating bright "beads" of light in a ring around the moon.

Diamond ring
When only one of Bailey's beads remains, the moon will look like a diamond ring in the sky.

Totality! 
THE MOON WILL COMPLETELY BLOCK THE SUNLIGHT! Totality will last about two and a half minutes, depending on where you are. And it will be amazing. Night will fall during the middle of the day, and instead of the sun, there will only be a black disc visible in the sky.
For a few brief seconds at the beginning of totality, you may be able to see the sun's red outer photosphere and chromosphere. If you are lucky, you may even see prominences, red streamers of light created by eruptions on the sun.
You'll be able to see the stars and planets during the day. In the United States, you'll be able to see Venus, Jupiter, and maybe Mars and Mercury.
The light will create a 360-degree sunset.
And for a few brief minutes, you'll get to see the sun's corona...outer wispy layers of ionized gas that are only visible during a total solar eclipse. The translucent shafts of light shining out from all sides of the sun is one of the rarest sights in nature, and can be as bright as a full moon at night. This is the main source of light during an eclipse. If you have a telescope or binoculars, you can look for loops and arcs in the corona that reveal the sun's magnetic fields. The corona is very difficult to photograph, and photographs aren't able to capture the full live experience of viewing.

Then, Bailey's beads will become visible again, the umbral shadow will continue moving west, and everything else will happen in reverse order.

AND WE GET TO WITNESS IT! This is a cosmic MIRACLE. I know the word "miracle" has religious connotations, but I can't think of a good secular equivalent to describe how incredible it is that this happens and that we get to be alive and on earth and in the United States to see it.

So what are you waiting for?! Make your plans! Figure out the closest path of totality and tell your boss you're taking the day off.

Here's your packing list:
- Binoculars and/or telescope
- Eclipse glasses
- A pinhole camera (piece of cardboard with a hole poked in it)
- A large piece of white posterboard or foamcore board to see shadow bands
- A full tank of gas
- A sense of wonder.

See ya in 54 days, solar eclipse.



Learn more about the upcoming solar eclipse here, here, and especially here.