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Touring The Evening Skies

December 11, 2010
By Jim Bonser
At last! Something exciting to talk about! This month we will be treated to a total eclipse of the moon – an event we have not seen for almost three years! Of course, even though it will occur, there is no guarantee we will see it because Iowa clouds seem to have a sixth sense about these events and often show up en mass to block our view. I can remember a number of ‘almost got to see it’ events in the past. Once, the skies were perfectly clear and a group of us went inside after we got our scopes set up to look at some slides taken by another amateur. When the time came for the eclipse to start, we headed back outside only to discover the sky had become completely overcast! Another time I was determined to photograph a lunar eclipse and when I saw some clouds appearing on the western horizon, I put all my equipment in my car and my son and I took off to the southeast corner of the state where the internet satellite maps assured us that the skies were clear and would remain so. Let’s say we had a nice drive to Ottumwa, but no eclipse photos!

Let’s hope for better weather this time around! Things don’t always go wrong and I have a number of beautiful pictures of a copper colored moon that I took of an eclipse that happened in August of 2007. The circumstances of this eclipse will be very similar. Totality will begin about 1:30 A.M the morning of December 21. Totality will last 1 hour 13 minutes with mid-eclipse occurring about 2:17 A.M. Don’t you wish eclipses understood the concept of prime time? Some things are just not under our control! It could be worse, though – mid- eclipse of the August eclipse I mentioned earlier occurred at 5:37 A.M. – I didn’t get much sleep that night at all; I did get some great pictures, though! I hope you will be able to stay up and watch this one, even better, take some pictures of your own. With today’s digital cameras there is no guess work about the correct exposure, just adjust the iso value or shutter speed of your camera until you get a pleasing picture. Use a tripod if you don’t have a telescope with a clock drive to keep the camera pointed at the moon. If you use a tripod, try to set the ISO value as high as possible in order to use a short exposure time. This will minimize blurring of the moon as it moves through the sky relative to you and your camera. The moon traveled slightly deeper into the Earth’s shadow than it will this time, but it should still be a beautiful sight!

Venus is the bright morning star rising about 3 hours before the Sun this month. In a telescope it goes from a nice crescent as December begins to a half lit ‘quarter moon’ shape at the end of the month. It also shrinks to about half of its early December diameter. Of course Venus itself does not get smaller, it only appears smaller because it is moving away from us in its closer and faster orbit around the sun.

Saturn will also be in the predawn eastern skies. On the nights of December 28 and 29, the moon will be a little above and to the right and then below and to the right of brilliant Venus. Saturn is always a soft beautiful golden color against the bright background stars.

Jupiter is slipping fast toward the western horizon as December goes by, but will be visible in the early evening sky all month long.

The Geminidmeteor shower should be a good one this year if you are willing to stay out late or get up several hours before dawn to watch. The Geminid shower is usually a pretty good one with an average of 1 to 2 meteors a minute during the peak which occurs this year on the night of December 13 with the best rates during the hours before dawn on the 14th.

One final challenge for those of you who enjoy a challenge, is an occultation of Mars by the moon on December 6th. This will be difficult to see, especially in Iowa where the horizon is typically very hazy, but I think it is worth a try. You will have to find an extremely thin crescent moon an hour or so before sunset. An extremely difficult task unless you have access to an accurate goto telescope setup and ready from the night before since there won’t be any stars out yet to get it aligned. The moon actually covers Mars about 3:20 in the afternoon and then moves out of the way about 4:10. With the blue sky for a background it would make a pretty picture, but be very careful if you attempt it. The Sun is not far away and even a very brief glimpse of the sun through a telescope or pair of binoculars can cause permanent eye damage – even blindness!

Clear Skies and have a Merry Christmas!



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