The upcoming total solar eclipse of 2017 August 21, by Froderick Frankenstien from Fresno

[Above: Public-domain image by Luc Viatour of the total solar eclipse of 1999 August 11, which I saw through a hole in the clouds near Augsburg, Germany. Totality does look just like this.]


On 2017 August 21, the first total solar eclipse will be visible from the 48 contiguous United States (or CONUS) since 1979. In a solar eclipse, the Moon casts a shadow on Earth. Between 2-5 solar eclipses (with at least partial phases) occur somewhere on Earth every year.

Aside from occurring in the CONUS, what will make the eclipse of 2017 August 21 special is that, along a narrow track only about 50 miles wide, the Moon will completely blot out the Sun’s bright surface, or photosphere, for a maximum of 2 minutes 40 seconds. This is called a total solar eclipse, and they generate great excitement.

Outside this path of totality, the Moon will not blot out the Sun’s bright surface completely. Still, the partial phases will be visible throughout the CONUS. Here is a map of the eclipse track that includes partial phases:

http://www.americaneclipse2017.org/observing-the-eclipse/weather-prospects/

The partial phases are as different from totality as day is from night—respectively and quite literally. If you meet someone who only “thinks” they've seen a solar eclipse, they've seen a partial.

It isn't for nothing that a total solar eclipse is called “Nature's most awe-inspiring phenomenon.” As Brian May has noted, “The first time you see totality, you really understand where you are, on a piece of rock hurtling around the Sun. It’s an awesome feeling—a life-changing experience.”

He's right: it looks and feels like the end of the world. There is a noticeable temperature drop, of as much as 15 degrees F. Night turns into day for 2 minutes throughout Oregon, where I will be, and at most 7 minutes 40 seconds anywhere during totality at any eclipse. Subjectively, this will feel like about 30 seconds: all total solar eclipses feel much shorter than they are.

There are surrealistic shadows in an eerie twilight, unlike any other. You can see the Moon's shadow coming before totality, and moving away afterwards. There are sunset colors all the way around the horizon. People scream. Dogs howl. Birds come out and sing afterwards, because they think it’s morning.



You can see the hot gas escaping from the Sun, the solar corona. All over the world, people have myths about a dragon eating the Sun, because that's what it looks like. People worldwide have also observed that if you beat on drums, smash pottery, or otherwise make lots of noise, the dragon will release the Sun and the day will soon go back to normal: it works every time.

Because of this, most hotels in the eclipse track have been booked solid for two years. Some of the few with vacancies left are gouging people 3-4 times the usual room rates. I made my reservations four years in advance. I had to find a small, privately run hotel in Oregon (and we are full). None of the major chain hotels would take reservations so far in advance, and they thought I was some kind of nut (and no, I didn’t mention anything about staple guns). It didn't help when I tried to explain, “But I want to observe the total eclipse of the Sun...”

Another reason I made reservations there is that they’re on the east side of the rain shadow of the Cascade Mountains, in the semi-desert of east Oregon. To see the eclipse, you will need clear weather. For a map of weather prospects along the path of totality, see here:

http://www.americaneclipse2017.org/observing-the-eclipse/weather-prospects/

You may still be able to get a room outside of the eclipse track, say in Portland or Eugene. Then, before dawn on eclipse day, drive east, to the semi-desert on the east side of the Cascades, or in the fossil beds or national forests farther east. You can get a detailed, interactive map of the path of totality here:

https://www.eclipse-chasers.com/php/tseNext.php?TSE=tse2017d

Traffic jams may be a problem, so good luck!

If things do work out, and this is you first total eclipse of the Sun, my recommendation is not to try to do serious photography of it. Just look around and enjoy the spectacle. After her first total solar eclipse, an astronomer's wife published an editorial in Sky & Telescope magazine with the title, “Now I Get It.”

A common, ordinary camera, either digital or film, can get great people shots before and after. Just make sure the flash is OFF, since it will ruin the weird shadows that are the whole point of seeing the eclipse. It will also blind anyone around you, and they really won't like that. So, NO flash!

Don't look at the Sun during the partial phases, when the Sun is only partly covered by the Moon. You'll know when it's safe to look straight at the Sun, since everyone around you will be screaming at the top of their lungs. Again, this is not a subtle phenomenon: you'll KNOW it when it comes. Stop looking at the Sun when the Sun comes out from behind the Moon: your blink reflex will tell you when this happens. Don't hurt your eyes: outside of totality is when people hurt their eyes.

The only time it is ever safe to look straight at the Sun with your unaided eyes is during totality. You'll KNOW it when this comes: it isn't subtle. (By the way, it's no longer considered politically correct to call them “naked” eyes.)

During the partial phases of a total solar eclipse, which are over an hour before or after totality, you can hurt your eyes by looking at the Sun, the way you can hurt your eyes by looking at the Sun on any other day. The Sun doesn't know we're observing it: it amazes me how many people seem to think this. There also isn’t anything dangerous about the corona: it’s a million times fainter than the photosphere, which is why it is only visible during totality.

Eclipse glasses can be useful for looking at the Sun during the partial phases, but I don't like them. Eclipse glasses are often made of mylar and look like this:

https://en.wikipedia.org/wiki/Solar_eclipse#/media/File:Eclipsbrilletje.JPG

Mylar eclipse glasses supposed to be safe, but I am skeptical, especially when it comes to children. The problem is that children can move much faster than adult eyes can see. Suppose you give a child a pair of these glasses. He wads them up into his pocket, climbs a tree, falls out of the tree, plays a (forbidden) game of tag with his friends, plays a game of touch football, plays a game of tackle, wrestles with his friends in the mud—and then he takes these glasses out of his pocket, puts them on his face, and looks straight at the Sun. Do you think that's safe?

On the other hand, mylar eclipse glasses are better than nothing. No matter how many times you tell kids, "Don't look at the Sun," they're going to do it anyway.

Eclipse glasses are only necessary for kids or anyone else in these circumstances:

(1) during a partial eclipse of the Sun,

(2) during an annular eclipse, and

(3) during the partial phases of a total solar eclipse.

During a partial eclipse of the Sun, the Moon covers only part of the Sun's bright surface, called the photosphere. It makes the Sun look like a crescent. Because partial eclipses of the Sun can be seen over a much wider area on Earth than a total solar eclipse, the totality of which can only be seen along a narrow track only a few hundred kilometers wide, many more people have seen partial solar eclipses than total solar eclipses. Really not much happens during a partial eclipse: it doesn't get dark out. Unless you knew something was unusual about the Sun that day, you probably wouldn't notice it. Don't look at the photosphere without eclipse glasses (and I'm not crazy about looking at the Sun with eclipse glasses, for reasons described above), it'll hurt your eyes the way looking at the Sun normally does, when the Sun isn't in eclipse at all.

During an annular eclipse of the Sun, the Moon does pass directly in front of the Sun. Because of the Moon's elliptical orbit around Earth, and Earth's elliptical orbit around the Sun, during an annular eclipse there is still a bright ring of the solar photosphere visible all the way around the Moon. There was an annular eclipse of the Sun in Redding, CA, in 2012. During an annular eclipse, you don't get any of the weird effects of day turning into night for a few minutes the way you get during a total solar eclipse. This is because of that bright ring of photosphere still visible all the way around the Moon: day doesn't turn into night during an annular eclipse. ("Annulus" means "ring" in Latin.) Again, if you didn't know something unusual was happening with the Sun that day, you probably wouldn't notice it. Also again, don't look at the photosphere without eclipse glasses (and I'm not crazy about looking at the Sun with eclipse glasses, for reasons described above): you'll hurt your eyes.

During the partial phases of a total solar eclipse, you can see the bright solar photosphere, on one side of the Sun, just like during a partial solar eclipse, or during the partial phases before the annularity of an annular eclipse. Again, don't look at the photosphere without eclipse glasses: you'll hurt your eyes (and I'm not crazy about looking at the Sun with eclipse glasses, for reasons described above).

During totality of a total solar eclipse, the Moon covers all of the Sun's photosphere. Day turns into night, and you can see the solar corona, which is the hot gas escaping from the Sun. The corona is only one millionth as bright as the photosphere: it's quite safe to look at during totality, and ONLY during totality, with your unaided eyes.

During totality is the ONLY time it is ever safe to look at the Sun, without eclipse glasses. You will know when this starts, since everyone around you will be screaming, because it will look and feel like the end of the world.

For the eclipse on 2017 August 21 in Oregon, totality will last only about 2 minutes. You will know when totality ends, because of your blink reflex. Stop looking at the Sun after you blink when a small part of the photosphere re-appears, and the corona disappears, and daylight returns. If you must look at the Sun after this, do so only with eclipse glasses.

The partial phases of the eclipse in Oregon will begin at about 9 a.m., depending on where you observe. This is called “first contact.” The partial phases will end at about 11:45 a.m. in Oregon: this is called “fourth contact.” Only the most fanatical astrophotographers will still be observing after this: most everyone else will be celebrating. Second contact and third contact are the beginning and end of totality, respectively. They will be a little after 10 a.m., throughout Oregon.

I hope you know that once you see a total solar eclipse, you will be addicted for life? The first thing everyone says immediately after third contact is: "Where and when is the next one?" It'll be in Chile on 2019 July 2, for 4 minutes 33 seconds of totality, so make your reservations soon.

—  Froderick Frankenstien from Fresno