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Cold Moon: this Week: December 4 - December 10, 2006.


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Venus Orbiter.
Pioneer Venus Orbiter. Image credit: NASA.

While things are cooling down in the northern hemisphere, they're heating up for the south as our “friends down under” are up for two meteor showers this week. We'll have a look a double stars, the distant Neptune, and practice judging stellar magnitudes. Be sure to read closely, because there just might be a suprise or two hidden in here! So, turn an eye to the sky because...

Here's what's up!

Monday, December 4 - Today in 1978, the Pioneer-Venus Orbiter became the first spacecraft to achieve Venus orbit.

Tonight the great Grimaldi will again capture the eye, but let's head southeast for another featureless dark grey oval - Crueger. Continuing south, the next crater - Darwin - is hard to see because of a rather un-craterlike appearance. Darwin is best caught by focusing on the rima that includes its eastern wall. Look for a Y formation pointing towards Crueger.

Although skies are bright, we can still see double. Locate 5.0 magnitude Lambda Arietis and its companion. This wide pair is an excellent challenge for binoculars. Both stars are F spectral types and should appear ivory in color to most observers. Having trouble in binoculars? Try a finderscope of equal power and aperture. To locate Lambda, look a finger-width west-southwest of Hamal - Alpha Arietis.

Tuesday, December 5 - Tonight is full moon and has been given names such as the “Cold Moon” or “Long Nights Moon.” This is the time of winter cold and nights have become long and dark. In some cultures, this is also called the “Moon before Yule.” No matter what it's called, early winter nights are indeed long and cold. Look for Luna moving high across the sky, opposite the now low Sun.

A star for all seasons is Polaris. Take the opportunity to see what magnification gives the best view of its 8.9 magnitude companion. This one can be tough for small scopes during Full Moon, so try for the right magnification to balance things like sky contrast and image scale. This teaches lots of lessons that really make a difference in resolving even more desperate disparates!

Wednesday, December 6 - With just a short time before the Moon rises tonight, have a look at a splendid set of colors - 1 Arietis. Because this pair is faint, you will need to apply “stellar geometry” to track it down. To find it, start with Alpha and Beta and form a right triangle whose third point is less than a finger-width northwest of Beta. Center the scope at moderate powers on that locale, then use the finder to pick out the nearest 6th magnitude star - 1 Arietis. Look for a 7.8 magnitude green companion south-southeast of the 5.8 magnitude white primary.

Tonight Southern Hemisphere observers should watch for the peak of the Phoenicid meteor shower. With an estimated hourly fall rate of 5, this particular shower might not seem exciting, but it has an unusual place in history. In 1956 over 100 meteors per hour were recorded - leading to the shower's discovery. This stream is believed to be the offspring of lost periodic Comet Blanpain, first observed in 1819. Although the exact time of peak activity is unpredictable, past observations show that it begins right after sunset radiating from a constellation already high in the southern sky. The shower is also unusual because it leaves few visible trails - but is well-known for occasional bright flashes and exploding fireballs!

Thursday, December 7 - Today is the birthday of Gerard Kuiper. Born 1905, planetary scientist Kuiper discovered the faint moons of Uranus and Neptune while first recognizing a belt of small particles outside the orbit of Uranus. In addition, Gerard was the first to realize Titan had an atmosphere, and specialized in studying the origins of comets in the solar system - especially those with orbits associated with the debris belt carrying his name!

Tonight let's honor Kuiper's achievements by observing Neptune and Uranus before they head too far west for good viewing. Look for magnitude 7.9 Neptune as a tiny high-power blue disk a little more than a degree northwest of Iota Capricorni. Magnitude 5.8 Uranus displays a slightly larger aqua disk south-southwest of Lambda Aquarii.
Watch as Pollux and the Moon accompany each other across the sky tonight...

Friday, December 8, 2006 - With an hour before moonrise, let's journey to a sparse portion of the Milky Way now high in the north just after skydark. Start by locating the two circumpolar constellations Cepheus and Cassiopeia and split the distance between Beta Cassiopeiae and Delta Cephei. Notice the stepping stones of 5th and 6th magnitude stars connecting them. Halfway between our two marker stars, go due south half a fist's width. This brings us to a region of some 5 degrees in diameter devoid of stars brighter than magnitude 6.5. Sweep the area with binoculars or a telescope. Any suggestions as to why a 20 square degree area of the Milky Way would be so deficient in visible stars? Think obscure...

Saturday, December 9 - Southern Hemisphere viewers, you're in luck again! Tonight will be the maximum of the Puppid-Velid meteor shower. With an average fall rate of 10 per hour, this particular apparition could also be visible to those far enough south to see the constellation itself. Very little is known about this meteor shower except that the streams and radiants are very tightly bound together. Since studies of the Puppid-Velids are just beginning, why not take the opportunity to watch? Viewing will be an all night event and although most of the meteors are faint, the Puppid-Velids are known to produce an occasional fireball.

For those of us not so lucky, we'll take advantage of early dark skies to study something that can't be easily seen from the southern hemisphere. Let's start with a star count. Tonight the Great Square of Pegasus is directly overhead. Dress warm and start about 75 minutes after sunset and begin to fully dark adapt your eyes. Have a seat and relax while the stars come out. You'll probably notice bright Vega to the northwest and Capella to the northeast right away. Within 10 minutes you'll see the four stars of the Great Square - all brighter than the 3rd magnitude. Not long afterward, 3.6 magnitude Omicron Andromeda will appear to the north. Looking toward the Great Galaxy you will notice 4.4 magnitude Nu. When you can see Nu, it's time to count stars within the “Great Square” itself. If you can see two stars direct then stars are visible to magnitude 4.6 and you're off to a great start. Add another and its deeper still - magnitude 4.8. Four stars means 5.0. Five, and you're down to 5.2. Six and it's 5.4, seven and it's 5.5. As each new star is noticed, check near Nu for signs of M31. Most folks will be able to hold three or four stars before noticing the “Little Cloud.” By seven, you will see it without any problem at all.

Sunday, December 10 - Be sure to look in the early morning hours for a close appearance of the Moon and Saturn. This will also be an occultation for a limited portion of our world, so be sure to check IOTA for details!

Tonight will be the peak of the Monocerotids - another example of an obscure and unstudied shower because no one is exactly sure of where the precise radiant is located. By keeping watch loosely on the constellations Gemini and Monoceros, you may see a few of these faint and fast meteors at a rate of 3-12 per hour. Who knows? Perhaps one of these strange meteors may have been responsible on this date in 1984 for striking a mailbox in Claxton, Georgia!

Now let's saddle up Pegasus and go Galaxy hunting - it's one wild ride!
Start by revisiting the brightest - 10.5 magnitude NGC 7814. To find it, locate Gamma and head west-northwest for an accompanying 7th magnitude field star. Power up on NGC 7814. Larger scopes will detect a razor thin dark dustlane bisecting the galactic core.

Now back toward Gamma about one degree for NGC 14. This average tilted spiral displays an asymmetrical structure complicated by the presence of what appears to be a faint star. This one needs a mid-sized scope, but small ones will detect a tiny blur of light under good dark sky conditions.

May all your journeys be at light speed... Tammy Plotner with Jeff Barbour.




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