|I won't have to worry about changing film for 2017 eclipse|
There are several considerations for selecting your observation spot. For me, the most important is the prospect for clear weather. When looking at various choices available to you, compare the probability for clear skies for the day and time of the eclipse. Another important factor is the length of the eclipse, but for me that is secondary. A total eclipse is one of those experiences for which the perception of the passage of time is highly altered. I was lucky to see one of the longest eclipses, 7 minutes of totality in 1991. The eclipse in Aruba was about half that duration at my location. Both seemed to last the same amount of time. I would select a location based on weather and then get close to the center line to maximize the duration. That is why you will find me in Madras, Oregon (2:00 min totality) on August 21st instead of Nashville, Tennessee (2:40 min totality). Do some research, there are many online sources for eclipse weather information. This chart shows the average cloud cover across the eclipse path.
If you are planning on photographing the total eclipse, my advice is do what I say, not what I did. I spent too much time fooling with my equipment in both of the eclipses I observed. For August 21st, I plan to snap a few pictures through my 80 mm refractor. I will not try and capture all the various phenomena associated with totality like Bailey’s Beads, the Diamond Ring, prominences, and the extent of the corona. My goal will be to have a nice personal souvenir, not to try and compete with the more experienced, skilled, and equipped eclipse photographers. They will share their results online. You can increase your chances of getting a good photograph by practicing on the Moon when it is near full. This will give you a good idea of what exposure to use and how large the image will be for your optics. I also plan on setting up my video camera to record the crowd, sky, and sound during the eclipse like I did in Aruba. I will not need to monitor it during totality. This will free me to observe as much of totality as possible using just my eyes and my 10 x 30 image stabilized Canon binoculars.
Observing a total eclipse without a solar filter is completely safe. It is the partial eclipse phase on either end of totality that is risky. It is not safe to look at any part of the Sun's surface (photosphere) for more than an instant. We have a natural instinct that prevents us from doing this. However, if you were determined to blind yourself, you could do it on any sunny day. What makes a partial eclipse a problem is our instinct is overridden by our curiosity. Furthermore, when it is a very thin crescent, the lower brightness can allow a person to look long enough to cause damage before wanting to look away. You won't notice the damage as it occurs, the eye does not feel pain. That is why it is important to have a variety of safe ways available to view the partial eclipse. Pinhole viewers, eclipse glasses, supervised telescopes/binoculars with solar filters firmly attached over the objective, and supervised telescopes/binoculars projecting images on screens are all good choices. A Sunspotter is one of the best tools if you have $430 to spend.
If you are lucky enough to be in the path of totality, you can look directly at the totally eclipsed Sun. You are now viewing the corona and chromosphere which are similar in brightness to a full moon. It is stunning to see in a telescope or binoculars but if you are looking when the eclipse ends, you will most likely damage your eye. It is important to know the duration of the eclipse at your location and stop looking about 30 seconds before it is predicted to end.
Just before the total eclipse and immediately after, there are two phenomena known as Baily’s Beads and the Diamond Ring. These occur when the only part of the photosphere that is visible is seen through valleys on the limb of the Moon. Baily’s Beads occurs when there is a crescent of valleys that the photosphere is peaking through. The Diamond Ring occurs when there is one last piece of photosphere visible. It forms the diamond and the corona forms the ring. Although many people have done it, including myself, it is not safe to look at even this last small part of the photosphere. I recommend looking at the Diamond Ring using a safe solar filter. That way when the total eclipse starts, your eyes will be more dark adapted so you can see more structure in the corona. More importantly, you will still be able to see when it is time to drive home! Most people that have seen the Diamond Ring directly saw it at the end of the eclipse. That is when I have seen it. It is the signal to look away from the Sun. It would be prudent to do so before the Diamond Ring but in my experience, most people don’t. The key is the duration of your look. I will not attempt to estimate a safe duration. I will only say it should be less than the time it takes to burn an image of it on your retina.
|Gia on the beach|
|Dan diving a shipwreck|
|Warned to not be under sleeping iguanas|
|The eclipse stamp shows Aruba was prepared|
|This may be the most laid-back place to view a total eclipse|
|No large prominences :(|
|Long exposure shows Jupiter and moons but smeared Moon|
|Picture of Diamond Ring worth risking equipment, but not eyeball|
|Beat this misaddressed postcard back|
|The photosphere has its charms too|
In my next post I will give details about the eclipse event conducted by Lowell Observatory at Madras High School in Oregon. I will describe my plans for contributing to this event and some ideas for activities you can do to enhance your experience on August 21st.