Saturday, May 28, 2016

Eclipse Links

In my opinion, it's important to know which sources of information are best to turn to when finding out about eclipses in general, and for the 2017 eclipse in particular. There's a lot of information out there- but I wanted to share with you the websites that I felt best shared information about this eclipse. The following is a list of excellent websites about eclipses, or the 2017 one. These have been put together by some of the top eclipse scientists and chasers that exist in the world today. (Some of these websites have Facebook and Twitter pages associated with them- look for the Facebook and Twitter logos and click on them.)

Links specific to the 2017 eclipse:


http://www.eclipse2017.org/eclipse2017_main.htm : Created by Dan McGlaun. Dan is not an eclipse scientist: he's just passionate about eclipses. He has traveled all over the world to see 12 total eclipses of the sun (as of May 2016).

http://www.greatamericaneclipse.com : Created by Michael Zeiler. He's a geographer that has traveled the world to see 8 total solar eclipses.

http://americaneclipseusa.com/ : Jay Ryan wrote the educational astronomy comic strip "SkyWise", which appeared in Sky and Telescope magazine from 1997-2001.

http://nationaleclipse.com/ : Dave Clark
doesn't "have any impressive astronomy creds or anything like that. (He's) just an average citizen who wants to help spread the word about this amazing event."

http://www.stjosepheclipse.com/podcasts.html : Michael Bakich is the senior editor of Astronomy magazine. This is his podcast about the 2017 total solar eclipse. If you click on "home" in the upper left hand corner, you'll be taken to the website highlighting the viewing party that he's hosting in St. Joseph, Missouri on eclipse day.

http://goseetheeclipse.com/ : This is astronomy and science educator Chap Percival's page about the 2017 eclipse.

 Maps of the 2017 eclipse: 

http://xjubier.free.fr/en/site_pages/solar_eclipses/TSE_2017_GoogleMapFull.html : created by Xavier Jubier. The area in between the red lines is where the eclipse is total. Click anywhere on the map for local circumstances. You can switch the view from "satellite" to "map" in the upper right hand corner.

http://eclipse.gsfc.nasa.gov/SEgoogle/SEgoogle2001/SE2017Aug21Tgoogle.html : NASA's map of the eclipse. The area between the blue lines is where the eclipse is total. You can click on this map for local circumstances, as well.

(note that the times listed on the above 2 maps is in Universal Time; I'll explain how to convert to local time in a later post
.)

http://www.greatamericaneclipse.com/blog/2014/11/28/10-foot-map-of-the-great-american-eclipse : an excellent map of the eclipse created by Michael Zeiler. You can click on the map to bring it up full size. (You can also find individual maps for each state on his www.greatamericaneclipse.com site mentioned above; see "maps" at the top".)

Links about eclipses in general (science):

http://www.mreclipse.com/MrEclipse.html : Created by Fred Espenak. He is a retired astrophysicist. When he was working for the Goddard Space Flight Center, he helped create detailed maps of eclipse paths with his predictions. He now fuels his enthusiasm for the subject by continuing to chase total eclipses. He has traveled to see 27 of them.

Links about eclipses (enthusiastic amateur sites):

http://www.beingintheshadow.com/ : Created by Kate Russo. She saw her first total eclipse of the sun in 1999- and became addicted. Her passion is especially notable in the section titled "The Experience" at the top of the page. It is well worth reading the links on that page. She has seen 9 total eclipses.

https://www.eclipse-chasers.com/Map.html : Created by Bill Kramer. Lots of good links and information here. He has seen 16 total eclipses. One of the links within the site shows how many total eclipses various eclipse chasers have seen:  https://www.eclipse-chasers.com/php/tseChaserLogSums.php Note that there are many people who have chased multiple eclipses that have not contributed their name to this list. Seeing a total eclipse of the sun can be very addicting!

http://eclipseguy.com/ : Created by David Makepeace. He is a filmmaker, and obviously very passionate about eclipses. He has seen 13 total eclipses.

https://groups.yahoo.com/neo/groups/SEML/info : This is a discussion group about eclipses. Many of the top eclipse chasers are members. I've learned so much from being a member here. You have to join to post, but you can browse through the archives and use the search engine to look at some of the posts.

Sunday, May 15, 2016

What happens during a total solar eclipse?

So, what is it like to experience a total solar eclipse? Why do some people travel all across the world to see them? Actually, the best way to describe it is to just use 3 words: Go see one. No description- written or verbal, no photo, no painting, no video could EVER come close to describing the majesty of a total eclipse of the sun. Although it's impossible to convey the experience, you may be curious to know what happens during one. So the following is my attempt to answer that.

Before I go on, let's assume a few things: 
1. That you're protecting your eyes using PROPER MATERIALS and PROPER METHODS during ALL of the partial phases and when the sun is not eclipsed (through a proper solar filter or looking at a projected image of the sun). I'll post about this later.
2. That you are looking directly at the eclipse during TOTALITY with NO PROTECTION. It is safe to do that- but only during totality.

3. That you're going back to protecting your eyes after totality.
4. That you have a wide view down to the horizon in all or most directions (or as close as possible).
5. That the sky is clear or mostly so.

So, it's eclipse day. You've arrived at your observing site, hopefully well before the eclipse starts. You can spend that time taking advantage of what the location has to offer: perhaps there are trails for walking, a pool for swimming, or maybe you're at a festival with games and other activities. Or perhaps you've brought something to do on your own- like a book to read, or a ball to throw around. Of course, you could always spend the time talking with others- certainly people you already know at the observing site, and perhaps new-found friends- all there to share in the grand celestial experience. Look around before the eclipse begins. Sure, there may be lots of people at the observing site, but I encourage you to look at the sky and other natural features of the area at this point. Notice how you're about to experience an incredible, dramatic natural event in just a few hours- yet there are NO signs from nature indicating that it's going to happen! The sun is still shining brightly, and animals are behaving as they normally do.

It's easy to look up the time when the eclipse begins at your location. Sure enough, right on time, (as you look through your protective filter or at your projected image) you'll see that the sun appears to have a dent taken out of it. That's not a dent, of course- that's the moon coming in between the sun and the earth. As the minutes tick away, the moon covers more of the sun. 10%, 20%, 30%- and so on. The progress seems slow. It's likely that most people at your location are paying only some attention to the eclipse: they're likely paying attention to the eclipse every once in a while as they talk about- and do- other things. You may find yourself doing the same.

But at some point, changes begin to happen. The light level begins to drop, the temperature slowly begins to fall, and a strange calmness fills the air. The changes will probably not all happen at the same time, but will likely happen within a few minutes of each other. How much the sun is covered when the changes start to happen can depend on various factors: the atmospheric conditions, the experience of the observer, and how much they're paying attention. The changes are subtle at first, but happen with increasing intensity as time goes on. They are also different than anything else you're used to experiencing in nature. The light level drop is not like that of a sunset- the light is colored differently, and you'll notice that the dimmest part of the sky is to the west. Shadows become sharper instead of longer. The strange calmness that fills the air is similar to what you might experience just before a severe thunderstorm- but really, it's unlike anything you've ever felt before. The sun has now been reduced to a crescent, and it is still shrinking. 60% covered... 70%.... 80%..... 90%..... The changes become more noticeable.

The sun is now over 95% covered. Everyone is paying full attention to the eclipse. There is an undeniable tension.  You're now less than 5 minutes away from totality. Look to the west. You may notice the sky is dramatically dimmer in that direction. The shadow of the moon is approaching. You may start to understand why people living many years ago- who would have not been able to predict or understand what was happening- would have been very fearful.

96%.... 4 minutes to go.... 97%.... 3 minutes..... 98%..... 2 minutes... The solar crescent is shrinking. The excitement in the crowd builds. An orange or yellow glow starts to be visible on the horizon. The changes in the sky and across the landscape continue- at a faster and faster pace.

One minute to go. The light level, which has been dropping slowly over the last few minutes- is now dropping with each passing second. It's like a dimmer switch is being turned on the world around you. Look to the west- you see a curtain of darkness filling the sky in that direction. This is the shadow of the moon racing toward you at thousands of miles per hour. You feel completely unable to stop what's happening. You start to feel a chill- literally and figuratively. People around you start to get very excited. It's an incredible experience.

You take one last look through your proper solar filter- or at the projected image of the sun- and see the thin solar crescent break up into a string of beads. These are sunlight shining through valleys on the moon while mountains in between them block the rest of the sunlight.  The beads last for a few seconds and then appear to get swallowed by the moon until one remains. Then it disappears.

When you look up, the sun- the very thing you need for light and life- is gone. It's been replaced by a black hole in the sky. That's the moon- coming exactly in between the sun and the earth. The moon appears to be surrounded by a pearl- colored glow. This is the sun's corona- its outer atmosphere. It's always there, of course, but it is hidden by the glare of the sun's photosphere (its surface). The photosphere is the part that is dangerous to look at- that's why you have to protect your eyes when any part of it is visible. When the photosphere is completely blocked, it's safe to look at the sun without protection and the corona is revealed in all its glory.

"Glory" is a good word for the corona- people have used the words "The Eye of God" to describe it. It is absolutely SPECTACULAR. You'll see incredibly fine lines, loops and strands of detail. Every one of those details is believed to be searingly hot (2 million degrees Celcius!) plasma tracing the lines of an enormous, chaotic magnetic field that surrounds the sun.  Some people report hints of color in the corona, but the dominant color is white. The inner sections of the corona show the most detail, while the outer corona stretches into the sky like glowing wings. Look closely: you may notice reddish flares of light reaching up into the inner corona. These are prominences: giant explosions of hydrogen gas that burst into the lower sections of the corona. Prominences do explode from the upper sections of the solar surface and then rain back down again- but you don't notice that motion during the few minutes of totality. You'll see them like a freeze frame from a movie. Notice how the prominences have different shapes: some are vertical, some are loops, some are arches- and others.

The eclipsed sun is commanding your attention- but force your gaze away from it for a few moments to look at some other amazing things. The sky above you is a deep blue- similar to deep twilight. An orange (or similar) colored glow is visible all the way around the horizon: a 360 degree sunset. A few of the brightest stars and planets may be visible. It's like a scene from another world. But your eyes will be drawn- again- to the beautiful corona.

You don't just see things during totality- you'll feel things as well. Take a moment to notice them. The temperature has dropped noticeably, and the strange calmness that started as totality was approaching is now even more dramatic. You may suddenly feel connected to the universe. It's an indescribable feeling.

Listen: how are other people reacting? In many cases, people cheer the start of totality, but as the eclipse progresses, the volume begins to decrease. Everyone is looking around, transfixed by the experience.

Look to the west again. Notice how the sky in that direction is becoming brighter- the trailing edge of the shadow is headed your way. You take one last look at the totally eclipsed sun. A reddish arc may appear on the edge of the sun. This is the chromosphere- a thin layer of hydrogen gas between the photosphere and the corona. A few seconds later, a bright ray of sunlight pierces through a deep valley on the edge of the moon- the "diamond ring" effect. Totality has ended- it is now time to go back to protecting your eyes. Even though a partial eclipse is still occurring as the moon moves away from the sun, most people don't pay very much attention to that anyway- because the time after totality is very anticlimactic! Instead, look around at the sky and the landscape. Notice how fast it gets bright again! The sun has returned.

Don't be surprised if you're overwhelmed with emotion at this point.....