Natural Calendar December 2010

Natural Calendar - December 2010

The purpose of this feature is to give scout leaders, educators and naturalists an idea of some of the natural events coming up each month. We will try to cover a variety of natural events ranging from sky events to calling periods of amphibians, bird and mammal watching tips, prominent wildflowers and anything else that comes to mind. We will also note prominent constellations appearing over the eastern horizon at mid-evening each month for our area for those who would like to learn the constellations. If you have suggestions for other types of natural information you would like to see added to this calendar, let us know!

Note: You can click on the hyperlinks to learn more about some of the featured items. To return to the Calendar, hit the "back" button on your browser, NOT the "back" button on the web page. All charts are available in a "printer friendly" mode, with black stars on a white background. Left clicking on each chart will take you to a printable black and white image. Please note that images on these pages are meant to be displayed at 100%. If your browser zooms into a higher magnification than that, the images may lose quality.

Though we link book references to nationwide sources, we encourage you to support your local book store whenever possible.

Notes and Images From November 2010

NGC 660, November 7th, 8th, 9th and 10th, 2010. Six inch f12 Refractor and ST 2000XCM CCD camera. Total exposure time was 14 hours in 10 minute sub-exposures. For a high resolution version of this image, click here.

In Notes and Images last month we talked about a future collision between the Andromeda Galaxy and our Milky Way Galaxy. This month we took an image that may show the aftermath of a galactic collision.

NGC 660 is an unusual type of galaxy called a polar ring galaxy. Located in Pisces near the Pisces - Aries border, it is believed to be around 24,000,000 light-years distant. The ring of younger stars that circles the older core is thought to be the remains of another galaxy that has been shredded by the gravitational forces involved in a galactic collision.

Many background galaxies are visible in the larger version of the image, which can be seen by clicking on the image at right.

We imaged NGC 660 over the course of four nights after the passage of a cold front. The temperature dropped quite low for early November, and the nights were very quiet. There were no insect sounds from our field, only the occasional sound of a passing freight train, whose horn would elicit a chorus of high yips and howls from our resident coyotes.

Sky Events for December 2010:

The Winter Solstice for the Northern Hemisphere occurs at 5:38pm Central Standard Time on December 21st. The solstice occurs about 15 hours after a total eclipse of the Moon (see below). This is the longest night of the year for the Northern Hemisphere.

This year's Geminid Meteor Shower peaks in the morning hours of December 14th. Viewing conditions should be very good, with the first quarter moon setting around midnight.

Evening Sky:

Look for Jupiter due south at dusk at mid-month, about 50 degrees above the horizon. It will appear before any other star-like object. This is a great time to view the giant planet.

Both Mars and Mercury are very low in the southwestern sky after sunset, but are difficult to pick out of the twilight glow without optical aid.

Morning Sky:

The first Total Eclipse of the Moon in almost three years occurs in the early morning hours of December 21st. The Moon should enter the umbra, or the darker part of Earth's shadow, about 12:33am CST. Totality begins about 1:41am CST. Mid-eclipse should be about 2:17am CST, and the Moon will leave the umbra about 2:53am CST. The copper-colored eclipsed Moon will be in the constellation Taurus, and will be surrounded by the brilliant stars of Orion, Gemini and Auriga. The spectacle will definitely be worth the sleep that you will lose! A pair of binoculars or a small telescope will enhance the view.

Saturn rises about 1:20am at mid-month, and will be in great position to view in the predawn sky before sunrise. The rings have opened up to 10 degrees from an edge-on view.

Venus is a brilliant -4.9 magnitude and rises around 3:30am at the beginning of the month. If you wait until the sky begins to get brighter as dawn approaches, you can view the beautiful small crescent in binoculars.

All times noted in the Sky Events are for Franklin, Tennessee and are Central Standard Time. These times should be pretty close anywhere in the mid-state area.

The Orion Nebula, Messier 42, February 2008, 85mm Apochromatic Refractor and & ST2000XCM CCD Camera, Total Exposure Time 2 Hours. Clicking on the image will take you to a larger higher resolution image.

Constellations: The views below show the sky looking east at 9:30pm CST on December15th. The first view shows the sky with the constellations outlined and names depicted. Star and planet names are in green. Constellation names are in blue. The second view shows the same scene without labels.

Look for the bright stars Castor and Pollux in the constellation of Gemini, The Twins. Compare the colors of the bright stars Betelgeuse and Rigel in Orion. Betelgeuse is a red giant and Rigel is a very hot, blue-white supergiant. If you have a telescope, point it to the center of the three "sword" stars below Orion's belt. There you will find the Orion Nebula, M42, one of the most magnificent emission nebulas in the sky. The pink glow of hydrogen alpha light is visible only in very large telescopes and the nebula appears as a small greenish glow in small telescopes. Crouching beneath the feet of Orion, is Lepus, the Hare. Sirius, the brightest star in the sky, shines below Orion. Sirius is in Canis Major, the Great Dog, and for that reason is known as the Dog Star. In the late summer, Sirius rises at the same time as the sun. Because of this, the late summer days are known as the "dog days." The faint constellation Monoceros, the Unicorn, follows Orion over the eastern horizon. Low in the eastern sky below Gemini is Canis Minor, with its bright star Procyon. Procyon means, "before the dog," and refers to the fact that Procyon rises just before the Dog Star, Sirus. Look below Gemini and see if you can spot the faint glow of M44, the "Beehive Cluster." This cluster is located in Cancer, the Crab.

December 15th, 9:30pm, Looking East

On Learning the Constellations: We advise learning a few constellations each month, and then following them through the seasons. Once you associate a particular constellation coming over the eastern horizon at a certain time of year, you may start thinking about it like an old friend, looking forward to its arrival each season. The stars in the evening scene above, for instance, will always be in the same place relative to the horizon at the same time and date each December. Of course, the planets do move slowly through the constellations, but with practice you will learn to identify them from their appearance. In particular, learn the brightest stars (like Sirius and Procyon in the above scene), for they will guide you to the fainter stars. Once you can locate the more prominent constellations, you can "branch out" to other constellations around them. It may take you a little while to get a sense of scale, to translate what you see on the computer screen or what you see on the page of a book to what you see in the sky. Look for patterns, like the three stars in a line in Orion's belt.

The earth's rotation causes the constellations to appear to move across the sky just as the sun and the moon appear to do. If you go outside earlier than the time shown on the charts, the constellations will be lower to the eastern horizon. If you observe later, they will have climbed higher.

As each season progresses, the earth's motion around the sun causes the constellations to appear a little farther towards the west each night for any given time of night. If you want to see where the constellations in the above figures will be on January 15th at 9:30pm CST, you can stay up till 11:30pm CST on the December 15th and get a preview. The westward motion of the constellations is equivalent to two hours per month. For instance, if you want to see what stars will be on your eastern horizon on March 15th at 9:30pm CST (3 months later), you would need to get up at 3:30am CST in the morning on December 15th (3 months times 2 hours/month = 6 hours).

Recommended:

Sky & Telescope's Pocket Star Atlas is beautiful, compact star atlas. It is destined to become a classic, and is a joy to use at the telescope.

A good book to learn the constellations is Patterns in the Sky, by Hewitt-White. You may also want to check out at H. A. Rey's classic, The Stars, A New Way to See Them.

For skywatching tips, an inexpensive good guide is Secrets of Stargazing, by Becky Ramotowski.

A good general reference book on astronomy is the Peterson Field Guide, A Field Guide to the Stars and Planets, by Pasachoff. The book retails for around $14.00.

Starry Night has several software programs for learning the night sky. Visit the Starry Night web site at www.starrynight.com for details.

Amphibians:

Upland Chorus Frog

December really marks the beginning of the breeding season for our Tennessee frogs and toads. We have had breeding choruses of Upland Chorus Frogs as early as December 4^th. Breeding even before Wood Frogs, these irrepressible inhabitants of flooded winter fields and other wet areas will call throughout the cold winter months. Listen for their call, which sounds like someone dragging their thumb across the teeth of a plastic comb, on mild wet winter evenings. Listen also for Southern Leopard Frogs. We hear them throughout the fall. Many other Tennessee frogs and toads can also be seen on mild December nights, but most are silent.

Recommended: The Frogs and Toads of North America, Lang Elliott, Houghton Mifflin Co.