A Partial Solar Eclipse

There is a partial solar eclipse, observable to varying extents throughout the US and Canada during the day on Thursday, October 23, 2014. Maximum eclipse is at 4:35 pm Mountain Time. (This blog contains some corrections to the times previously published.). This is only a partial eclipse, meaning that the Sun will not be totally covered at any time, and all necessary precautions should be taken before any attempt at observation.

Depending of course on the weather in your area, there are several options for observing this event. If you do not have the proper equipment yourself, the first and best option is to find an observing opportunity in your area, usually sponsored by colleges, museums or astronomical societies. Check locally, and if you cannot find anything, check the NASA Night Sky Network website.

In the Denver area, the Metropolitan State University of Denver Physics Department and  the Denver Astronomical Society  will have observing opportunities, as will the Community College of Aurora Observatory .

The partial eclipse begins at 3:18 pm, Mountain Daylight Time.
Maximum eclipse is at 4:35 pm, Mountain Daylight Time
The eclipse is over at 5:44 pm Mountain Daylight Time

Add 2 hours to those listed for the Eastern Time Zone and 1 hour for the Central Time Zone. Subtract one hour for the Pacific Time Zone. Observers in Alaska will see only part of the eclipse, and viewers in Hawaii will miss out entirely.

NASA produced lists of precise timings for many US locations can be found here, in PDF format, here: http://eclipse.gsfc.nasa.gov/OH/OHtables/OH2014-Tab05.pdf
And listings for Canada and Mexico can be found here: http://eclipse.gsfc.nasa.gov/OH/OHtables/OH2014-Tab04.pdf

If there are no organized observing opportunities in your area, you can observe the transit with very little equipment. However…. you must be careful. I think that most folks are smart enough not to ruin their eyesight by looking directly at the Sun, but in consideration of the horror stories I have heard, it is obligatory to caution everyone. Do not under any circumstances ever look directly at the Sun with your eyes, even if "protected" by sunglasses, photographic negatives or welder’s glasses. And never, ever look at the Sun through a telescope or binoculars even if you have a so-called eyepiece filter. Just don’t do it. And if you use one of the projection methods below, be sure that no one, especially not a child or animal, looks at the Sun directly either through the telescope or binocular projection.

You can use a pair of binoculars or a small telescope to image the transit, but I must warn you on several points.

  • First, as already stated, do not look through the binoculars or telescope with your eyes. This should go without saying, but I am saying it again. Just don’t do it.
  • Second, do not leave the projection on the Sun for too long. I suggest that you make a couple of minutes of observations, then turn the rig away from the Sun. After a few minutes, do it again. The reason is that the hot rays of the Sun are concentrated on the eyepiece of the telescope or binoculars and its gets very hot. Too much of this can shatter the glass and ruin the instrument.
  • Third, aiming this device is not always easy. Use the shadows as a guide, since of course you cannot look through the scope or binoculars. You might want to mount the whole device on a camera tripod or other mount, and I also suggest that you do a practice run the day before the transit.

All that said, you can make a decent observation instrument with binoculars (or a small telescope) and a couple of pieces of stiff, white cardboard: Set up for binocular projection of Venus transit

The basic idea is that you focus the image of the Sun through the binoculars (or telescope) onto a white card a foot or two away. You need to make a mask out of something like thick card stock or cardboard to help block the sunlight from falling directly onto the projection card, which will make it much easier to see. This is all much easier as well if you can mount it on a tripod or other adjustable mount. You will have to readjust it every few minutes because the Sun appears to move in the sky.

Ordinary pinhole projection may be used as well, but probably will not work well because the dot of Venus is small. Instead, you could try what I call "pinhole reflection," substituting a small mirror for the pinhole and projecting it about 20 feet to form a reasonably large image (~2 inches). Tiny mirrors for this are not easy to come by, so you can take a normal flat mirror and create a paper or cardboard mask for it with a small (1/8 to 1/4 inch) hole in it. The sunlight is then reflected from the hole onto some darkened wall nearby. I have used this for years with students, and while a bit tricky, can form a pretty good image of the Sun that is big enough to show Venus. Just be short that the hole (cut-out) is no more than 1/4 inch across, and that the reflection (projection) distance is about 20 feet. Too far and the image is too faint, too close and while it is bright, it is not properly focused."Pinhole reflection" of Sun (The graphic is just a suggestion of one way to do this.)

Again, I suggest that if all possible, find a local museum, planetarium or educational institution that is providing observational opportunities. But if you can’t do that, and don’t like my particular ideas or graphics here, there are are number of other websites with excellent ideas for this transit.

For a NASA page on how to safely observe the Sun, please see: http://eclipse.gsfc.nasa.gov/SEhelp/safety.html

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About Starman

Cosmic Awareness Facilitator. Astronomy, space, physics, science, planets, cosmology, reason, logic, clouds, sky phenomena, the environment, dogs and other animals, and other interesting stuff.
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