Lis Orihaku's page

Sorry for the long post, but I thought some of you might find this useful.

It has been over 37 years since the last total solar eclipse was visible in the United States (Feb 1979,) but next year we will play host to thousands of umbraphiles (eclipse chasers.) On Monday August 21st, the day after GenCon ends there will be a total solar eclipse that will cross across United States from Oregon (Salem) to South Carolina (Charleston.) Even if you are not in the path of totality, the rest of North America will be able to bear witness to a partial eclipse.

Total solar eclipses are one of those rare astronomical events that you need to experience, but you need to take some precautions and preparations to make it safe and awesome. While some might think that 9 months before is a little too much, some of you might want to take advantage of the holiday sales coming up.

First a note about safe viewing. Please take a moment to read the following advisory:
http://eclipse.gsfc.nasa.gov/SEhelp/safety2.html

Here is an interactive map that shows the path of totality:
http://xjubier.free.fr/en/site_pages/so ... tml?Lat=37

You might have noticed that the path of totality moves from West to East (i.e. Salem, Oregon will see totality long before Charleston, SC.) This may seem counterintuitive, since the sun rises in the east and sets in the west, but what is happening is that the moon's orbit is slower that the relative speed of the Earth axial rotation. Simply put, the sun is moving faster than the moon, so the shadow cast moves west to east. For those of you in the Midwest will note that northern Kansas City and southern St. Louis are on the edges of the path of totality. If you can, try to move close to the midline of the path of totality. The closer to the midline, the longer you will be in the shadow of totality. As far as viewing goes, the Midwest weather is somewhat unpredictable especially in August. I was checking out sites back in August, and had rain, clouds, and relatively clear skies on three days. Mobility has been a key to successful eclipse viewing. In 2012, there were parts of Brisbane it overcast, but the was a small window of semi-clear skies about 10 miles north where you could capture totality (most of the rest of the coast only got a glimpse of the partial eclipse.) Keep an eye on the forecasts. Here is a link to some important weather data for the 2017 eclipse:
http://www.eclipse2017.org/2017/weather.htm

If you are in the path of totality, here is a timeline of some of the things to look for:

First Contact: This is when the moon first begins to block out the sun.
Between First and Second contact: the moon will block out more and more of the sun. During the latter part of this time the moon will create a crescent shaped image. If you can find some spots that have projected shadows, you can see this crescent shape image.
Near Second Contact: ~10-15 minutes the darkness will grow and the temperature may drop noticeably. As it gets darker and darker, you might start to hear crickets and other animals acting strangely.
As Second Contact nears two things will happen. On the ground, you can see a shadow racing across the landscape (west to east) travelling at 1000 miles an hour. In the sky the moon will be surrounded by a glistening halo. Since the moon in not a flat surface, as the sun begins to "set" behind the moon, parts of light will shine through the crags and valleys. As a result you will see several points of light around the moon. With the shifting air temperature, these points of light will seem to pulsate. This phenomenon are called Bailey's Beads.
As the last point of light "sets" behind the moon you will have a moment called the "diamond ring." This is notable because you will see one brilliant point of light surrounded by a coronal halo around the moon. As this last bit of sunlight fades, Second Contact begins.

Once Second Contact begins, it is perfectly safe to watch the eclipse without your stylish eclipse glasses. Once Third Contact starts you need to put them back on. The moon is completely blocking out all of the sunlight. As this point you can see the solar corona. Depending on the amount of solar activity, you might be able to see some solar prominences. If you are photographing the eclipse you might be able to capture some other solar activity (e.g. solar mass ejections.)
Depending on where you are in the path of totality, the time in totality will vary from a few seconds, to 2 1/2 minutes (2mins, 40secs if you are at the point of the maximum eclipse.)
Once Third Contact occurs you need to put you eclipse glasses back on to watch. Everything that I just mentioned will happen in reverse, from the diamond ring, Bailey's Beads, etc. until Fourth Contact, and the eclipse ends.

If you decide to try to photograph the eclipse here are some helpful tips if you are using a DSLR (or mirrorless camera with interchangeable lenses):
1) Be mobile. You may need to find a clear skies, or a unobstructed spot to take pictures. Scout out multiple spots ahead of time in case you need to move.
2) Get solar filters for your camera. That's plural (see 3.) Practice using them so you know their capabilities.
3) Have a back-up. Take extra batteries, memory card/sticks (film?) Have a plan in case your primary camera malfunctions/breaks. (You can get some interesting landscape shots with a cell phone)
3) If you are using a large telephoto lens (600 mm or larger) get a steady tripod, and a remote triggering device. As you increase your focal length, minor movements can create tails. Some cameras have correction features that can correct this, but I am not a fan of this, since the camera can edit out some details that you want to preserve. I use a telescope mount with manual tracking features. This way I can make tracking adjustments without touching the camera.
4) Some tips about photographs:
a) TURN OFF YOUR FLASH. The moon is over 200,000 miles away, even with everyone on Earth taking a picture at the same time, isn't going to illuminate it. More importantly, the flash can ruin someone else's photo (and their night vision.) Be polite.
b) Take shots of the partial phases of the eclipse
c) Take pictures of the crowd, and the landscape
d) As Second Contact approaches TAKE OFF YOUR SOLAR FILTER
e) If you are going to take photographs of Bailey's Beads or the Diamond Ring, use the camera's sensor image display, DO NOT LOOK THROUGH YOUR VIEWFINDER. The light through your viewfinder will be concentrated to a much smaller area than looking directly at the sun. A telephoto lens increases the amount of light you are receive even more.
f) Take a series of exposures. Prominences and Coronal Mass Ejections will be visible in high speed; Coronal streamers at longer exposures.
5) Write your photograph routine down. As totality nears your excitement will build, and you will probably forget things. Having a checklist may help. Don't make it too lengthy, (you don't want to spend precious seconds reading, while totality races by) but give you enough details to remind you of key points.