Natural Calendar - December 2002

The purpose of this new 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.

Sky Events:

The Geminid Meteor Shower:  If you were clouded out of the Leonid Meteor Shower last month as we were, you may want to check out the Geminid meteor shower on the evening of December 13th and the morning of December 14th.  The meteors will appear to radiate from the constellation of Gemini (see Constellations).

The Winter Solstice:  The winter solstice, corresponding with the shortest day of the year and the beginning of winter for the northern hemisphere, occurs at 7:14pm CST on December 21st.  At this time, the northern hemisphere of the earth is tilted away from the sun the maximum amount possible.  The sun’s altitude in the sky above the southern horizon at noon is at its minimum for the year.  In the night sky, the full moon on December 19th rises higher above the horizon than any other full moon of the year.  I think of winter full moons as shining high in the sky and looking very clean, like they’re made out of ice. Summer full moons never rise as high above the horizon, and many times the atmosphere tinges them with shades of orange.  If these early sunsets are getting you down, you can take solace in the fact that the situation improves after December 5th.  Because of the earth’s tilt to the plane of its orbit, the earliest sunset and the latest sunrise do not correspond with the shortest day of the year, which occurs on the 21st.  The earliest sunset for our latitude this year occurs on the 5th, about two weeks before the solstice.  The latest sunrise occurs on January 7h, about two weeks after the solstice.  

Evening Sky:  For those who are willing to deal with the chilly temperatures, the sky holds some spectacular sights this December.  Saturn is truly magnificent this month and at mid-month rises at dusk.   The rings are near their maximum tilt to the earth and the planet is stunningly beautiful even in a small telescope.  Now might be the time to dust off that old telescope in the attic.  Look for the thin black division in the rings called Cassini’s division, discovered in 1675.  Jupiter rises around 8:45pm CST and is brighter than anything else in the eastern evening sky.  See the figure in the Constellations section for the positions of these planets.  The planet Mercury puts in an appearance in the western sky after sunset towards the end of the month, reaching its greatest apparent distance from sun (greatest elongation) on Christmas day. Look for it about 30 to 45 minutes after sunset above the southwestern horizon.  You'll need a good flat southwestern horizon to see it.  See the view  below.


Christmas Day, Looking Southwest


Morning Sky: 

At mid-month Venus and Mars rise together around 3:30am CST and should offer a pretty view.  Venus is much the brighter of the two, with Mars less than three degrees (about two fingers held at arms length) to the right.  The view below shows them at 6:00am on the 15th


The Sky on December 15th, 6:00am Looking East

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.


Constellations:  The views below show the sky looking east at 9:00pm CST on December 15th.  The first view has the constellation outlines and names depicted.  Star and planet names are in yellow.  Constellation names are in green.  The second view shows the same view without labels.  The constellation Auriga is now high in the eastern sky, with Saturn  below.  The bright stars Castor and Pollux in Gemini are below Saturn.  Below Gemini is Canis Minor, the Lesser Dog, with it's bright star Procyon.  Jupiter, brighter than any other object in the eastern evening sky, has just risen.

The beautiful constellation Orion dominates the southeastern sky.  The star Betelgeuse is a red giant and the star Rigel is a very hot, very bright supergiant.  Compare the color of the two stars.  If you have a telescope, point it to the center of the three "sword" stars below Orion's belt.  You will be pointing at the Orion Nebula, one of the most magnificent emission nebulas in the sky.  It appears as a small greenish glow in small telescopes.  Below Orion is Sirius, the brightest star in the night sky.  Sirius is in Canis Major, the Great Dog, and 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.”  Finally, crouching beneath the feet of the giant Orion, is Lepus, the hare.

December 15th, 9:00pm Looking East


December 15th, 9:00pm 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 Capella and Sirius 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 9:00pm CST, you can stay up till 11:00pm 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 9:00pm CST (3 months later), you would need to get up at 3:00am CST  in the morning on December 15th (3 months times 2 hours/month = 6 hours). 

A good reference book for learning the constellations is the Peterson Field Guide, A Field Guide to the Stars and Planets, by Pasachoff.  The book retails for around $14.00.  A good beginners software program for learning the night sky is the Starry Night Beginner program.  Visit the Starry Night web site at   The program retails for around $30.00 and contains a wealth of information.

Circumzenithal Arcs Fall, Winter and Spring are good times to watch for these beautiful  arcs that form directly overhead.  Be sure to look upward in the late afternoon anytime you have wispy cirrus clouds in sky.



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 4th.  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.  Many other Tennessee frogs and toads can also be seen on mild December nights, but most are silent.



 If you walk grassy fields that have some wetter areas, you may flush a Short-Eared Owl, a winter resident in Tennessee.  We have flushed them from fields at Pardue’s Pond near Ashland City, along the roads that go to Pace Point near Big Sandy, Tennessee, at Britton Ford near Dover, Tennessee and at Savannah Bottoms, south of Savannah, Tennessee.  These birds tend to occupy the same habitat as Northern Harriers, so if you see Harriers over grassy fields, be on the lookout for the owls.  They often begin flying in the late afternoon, coursing over the fields like a Harrier.  It’s a good idea to check any “Northern Harrier” you see in the late afternoon to make sure it’s not a Short-eared Owl.

Through the end of December, listen for the courtship dueting of Great Horned Owls at dusk and dawn.

You probably have already put out your bird feeders, but if you haven’t you're missing out on a lot of good looks at winter feeder birds.  This is a great time of year to start learning your birds.  Watch and listen for winter residents such as White-throated and White-crowned Sparrows, Yellow-bellied Sapsuckers, Red-breasted Nuthatches, Golden-crowned Kinglets and Brown Creepers. 

Recommended: The Sibley Guide to Birds, David Allen Sibley

For the eastern United States only, A Field Guide to the Birds East of the Rockies, Roger Tory Peterson

An inexpensive guide for beginners is the Golden Guide for Birds.


Night scenes prepared with Starry Night Pro software