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December Urban Observing December 1, 2013

Posted by aquillam in Astronomy, MichiganAstro, Urban Observing.
Tags: , , , , , , , ,


Comet ISON is still uncertain as I write this, but it’s unlikely to be a naked eye comet. Its pass by the Sun on November 26 took a big toll on it. If you have a telescope, look for it in Ophiuchus as the month opens. It’ll be up both at dawn and dusk. It heads northward through Hercules and Draco, ending in Ursa Minor at the end of the month. It becomes circumpolar around December 24, and is closest to Earth on the 26. Charts:http://www.aerith.net/comet/catalog/2012S1/2012S1.html
ephem: http://scully.cfa.harvard.edu/cgi-bin/returnprepeph.cgi?d=c&o=CK12S010

The solstice occurs on the 21 at 12:11. Here in Michigan , that means only about 8 hours of sunlight, which is great if what you really want to do is stargaze!

The Geminids are the best meteor shower for December. This year they peak on the 13 – 14. Under dark skies, this shower typically brings 50-100 meteors an hour. Urban observers still have a chance though, because the Geminids have a relatively high number of bright meteors, though that probably means only about 10 in an hour.

The end of the month brings the Ursid meteor shower. At 15 – 20 meteors per hour, this isn’t a spectacular show. However, it’s visible all night for those in North America, and it peaks just after the solstice, so it’s easy to watch. The best time is in the midnight to dawn window, but any dark time will work!


Mercury disappears into the glare of the Sun again as the month begins.

Saturn, Mars, and the Moon in Libra and Virgo.

Looking east at 7 AM on December 26. Image made using starry night.

Morning Planets

Mars is high in the southeast in the pre dawn sky. The Moon passes less than 5 degrees from it on the 25.

Saturn emerges from the pre-dawn glare into the southeastern sky early in the month. By mid month it’s a good target, and sunrise is so late you won’t even have to get up early! Look for a close conjunction with the Moon on the 28th.

Evening Planets

A crescent Moon and Venus low in the SW, and several summer skies objects higher up in the west.

December 5, 6 PM. Image made using Starry Night.

Venus is easily visible in the southwest all month just after sunset. It is particularly bright early in the month. Look for it to pair with a young crescent Moon  on the 5th around 6 PM.

Jupiter rises a few hours after sunset.  It’ll be perfect target for that new telescope you’re hoping for.

Deep sky objects

Jupiter and the winter constellations.

Looking east at 9 PM on December 15. Image made using Starry Night.

December brings many of the winter constellations. The Pleiades in Taurus is spectacular through binoculars, and generally visible even in very light polluted areas.  The Orion Nebula is also an excellent target for a small telescope, and is relatively easy to find. The Beehive in Cancer is a lovely wide open cluster, good for both binoculars or a small ‘scope.

Because of the early sunset, it’s still possible to catch M13 in Hercules, the double double (epsilon lyre) and the ring nebula (M57) if you head out soon after sunset. Don’t forget the double star Albireo while you’re looking.

The fall constellations, overhead, with several star clusters marked.

December 13, 9:30 PM, overhead. South is toward the bottom, and west is to the right. Image made using Starry Night.

By 6 PM, the double cluster in Perseus and M31, the andromeda galaxy are good deep sky targets. If you enjoy a good double star, check out Enif, the nose if Pegasus. It’s wide enough to separate with just a pair of binoculars.

This is a good time to watch for the minima of Algol too. There’s a nice one for those in the eastern time zone on December 13, at around 9:30 PM. If you’re not in the Eastern time zone, there’s a nice calculator at Sky and Telescope: http://www.skyandtelescope.com/observing/objects/variablestars/Minima_of_Algol.html

The Moon

The full Moon occurs on the 17.

image: http://www.lpod.org/coppermine/albums/userpics/normal_Mare-Crisium-2.JPG

Mare crisium, with several craters marked.

Mare Crisium with several craters marked. When looking naked eye, Yerkes and Lick are usually on the left side of the mare, and Shapley is along the southern edge. Click for original image source.

On December  5 in the evening the terminator will highlight the western edge of Mare Crisium. It is highlighted again on December 20, in the morning. There are several craters named for astronomers in this area, including Curtis and Shapley. Early in the 20th century, there was a great deal of contention about the size of the universe, and so, on the 26 of April 1920, Heber Curtis and Harlow Shapley met at the National Academy of Sciences in what has become known as “the Great Debate“. Curtis argued that the “spiral nebulae” were actually other galaxies, and the universe was essentially infinite in size. Shapley argued that the spiral nebulae were gas clouds and the universe was essentially the galaxy. It would be more than 10 years before observations would resolve the issue for real. In the meantime, Curtis become the director of the observatories at the University of Michigan. You can learn more about the debate at http://apod.nasa.gov/diamond_jubilee/debate_1920.html.



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