Total Solar Eclipse 2017 - Eclipse Basics

The Absolute Basics:

What is a total solar eclipse?

What is a total solar eclipse? Well, based on questions we've received, it's not at all out of line for us to give a VERY basic overview of the basic types of eclipses! This is important stuff; it's all too easy for eclipse veterans to forget that most people have never seen a total solar eclipse, and would really appreciate an honest description of what the difference between all these types of eclipses really are!

We're getting pictures together, to make this page easier to follow along with. Please be patient!
LUNAR ECLIPSE
This is an eclipse of the Moon, which happens when it's nighttime, and the moon passes through the shadow of the Earth. Now, the Earth's shadow is big - much bigger than how the Moon appears in the sky, so whenever the Moon goes through the Earth's shadow, everyone on Earth (on the side of the Earth where it's night) sees the Moon eclipsed. And a total lunar eclipse generally lasts for maybe a couple of hours or so.

Photograph courtesy of Dr. Howard Cohen, Emeritus Professor of Astronomy, University of Florida

This type of eclipse is very pretty, but it's nothing compared to the show the US is going to get on August 21, 2017!

SOLAR ECLIPSE
PARTIAL SOLAR ECLIPSES
These are eclipses where the Moon goes in between the Earth and the Sun, and passes right "in front of" the Sun as seen from the Earth.

Now, the Sun is very bright, and even though the Moon might be passing in front of it, there will almost always still be a part of the Sun that the Moon isn't covering up. SO LONG AS ANY BRIGHT PART of the Sun is still able to be seen - regardless of whether the Moon is covering other parts of it up - it is still just as dangerous to look at the Sun as it would be during any other (non-eclipse) time! You simply can't look directly at the Sun without proper eye protection ("eclipse glasses") during a solar eclipse - unless ALL of the Sun is being covered by the Moon. And that requires a very special set of circumstances!

You see, unlike with a lunar eclipse, the whole daytime side of the Earth is NOT EVER going to see the Sun covered up! In fact, the part of the Earth that sees the Moon totally covering the Sun is EXTREMELY small - maybe a strip of land about 50 miles wide or so! This strip is called the "path of totality", and if you want to see the Sun totally covered by the Moon, you HAVE to be in that path! If you're not in that path, then you will ONLY see a partial eclipse.

If you are not in the path of totality, the Sun will NEVER be completely covered by the Moon for you, and so you must ALWAYS use eclipse glasses to view the eclipse.

TOTAL SOLAR ECLIPSES
But if you ARE in that path of totality, then you will see the Moon cover up the Sun little by little (using your eclipse glasses, of course!), until for just maybe a minute or two (depending entirely on your exact location), the Moon COMPLETELY covers the Sun! During that brief period of time ONLY, we say that the Sun is being TOTALLY eclipsed. There is no bright part of the Sun that is visible any more, because the Moon is completely covering it! During that time, the totally eclipsed Sun is one of the most beautiful sights there is on Earth, and it can be safely looked at without any eye protection at all - because the Moon is completely covering the Sun! But the Moon keeps moving, and very soon the bright part of the Sun will come back out from behind it again. The second you see that bright part of the Sun come back into view, you must once again use eye protection to look at the eclipse.

How do we know what to be prepared for? Simple - First, you have to make sure you are in the path of totality. If you aren't, then you will ALWAYS need to use eye protection to look at the eclipse. If you are in the path of totality, you still have to have eye protection available to look at the partial phases of the eclipse, as the Moon is slowly covering up the Sun. Once you can't see anything through the eclipse glasses, then the Sun is being totally eclipsed, and it's safe to look at. The view of the "corona" of the totally eclipsed Sun won't be any brighter than the full Moon at night, and you can safely look directly at it. But once the Moon moves on, and the slightest bright piece of the Sun's disk becomes visible again, then you have to put the eclipse glasses back on - because totality is over for you!

And we have to say, if this simple explanation didn't do it for you - if you still have questions about when and how it's safe or not safe to look - then we have to advise you not to attempt to view the eclipse at all, using any method.

Did you order glasses from us? Are you worried about the big recall?
How do you know the glasses you got from us were safe to use?

Eclipse2017.org is on the American Astronomical Society's approved vendor list for eclipse glasses!

Also, please read the blog post we wrote about the safety of glasses ordered from Eclipse2017.org!

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