December 2009

Tony Martinez

Each month I will describe sights of interest in the night skies of South Carolina. These sights will be broken down into three sections; what you can see with the naked eye, with binoculars, and with a small telescope. The best time to view the night sky is at and around the times when the Moon is not visible, what is known as a New Moon; which will occur this month on December 16^th. For December, your best viewing nights will be from December 6^th through December 22^nd. The Star chart below is set for Florence, SC on December 15^th at 9 pm.

Meteor Showers

The November Leonids were a washout. Not only did the Leonids give a poor show, in South Carolina there were not enough meteors to even call it a meteor shower. I took a personal count of only 4 meteors per hour. To any of my readers who felt a great let down, I strongly encourage you to check out the Geminids meteor shower in December. There are only three “major” meteor showers each year: The Leonids in November, the Perseids in August, and the Geminids in December. Of the three, the Geminids get the least attention. My personal observations have shown that the Geminids are the most reliable; never overly impressive, but seldom a washout. The Geminids should peak between 1 am and sunrise on December 14. With the Geminids, it is also possible to have a good shower the night before and the night after the peak. So if your schedule work/school permits, give it your last try for 2009 meteor showers. Note: I define a good Geminids shower has 60 or more meteors per hour; good luck to us all.

Mercury

Mercury is one of the more difficult planets to view, only because of its close proximity to the Sun. So whenever there is a good opportunity to view Mercury, I will mention it in my column. It is also nice when the planet is visible just after sunset versus just before sunrise; except of course for the early morning risers. Start looking for Mercury in the southwest, right after sunset on December 17^th, but on the 18^th, you will have the advantage of a thin crescent Moon resting just above the elusive planet. Well above the crescent Moon will be the brightly shinning planet Jupiter. Start checking at 5:15 pm, but your best viewing may be between 5:30 and 5:45 pm. You can continue viewing Mercury for the next several days. If you can see a star just below Mercury, it is the star Nunki, in the constellation of Sagittarius. Your view of Mercury and the crescent Moon may look somewhat like the image shown below.

If you have a telescope, you may be tempted to view Mercury, but please do so only after the Sun has completely set. Never ever turn your telescopes anywhere in the direction of the Sun; to do so would result in severe eye damage. If you do see a telescopic view of Mercury, it will never be seen as a disk, because like Venus, it is between us and the Sun. Below is a size comparison of Mercury and the Earth.

Christmas Shopping

For all the last minute astronomy gift shoppers, I repeat some of the following thoughts/suggestions from earlier columns. Don’t buy telescopes from department stores; do buy telescopes from astronomy/telescope stores (on-line will do). When in doubt, for the beginning young or old astronomer, buy binoculars and star charts and how to guides. An established amateur astronomer always wants more accessories; ask him or her for a wish list. Astronomy software is another great gift; Starry Night software usually sets the standard in this area. Don’t forget astronomy books or magazine subscriptions. Also buy fun stuff like T-shirts and hats that show your hobby is astronomy.

Remember, careful thought and purchases can help lead a young person into a hobby that will last a lifetime. The image below may offer you some suggestions for your astronomy wish list.

To all my readers: Have a wonderful Christmas and a Happy New Year.

Naked Eye Sights: The Geminids meteor shower. The planet Mercury. Enjoy the arrival of winter’s favorites: Orion returns to dominate the sky for the next several months. Leading Orion is the wonderful Pleiades/Seven Sisters asterism. Following Orion is the brightest star in our nighttime sky, Sirius/ The Dog Star. The striking Northern Cross/Cygnus will slowly set in the northeast this month. The Cassiopeia asterism in the northeast doesn’t know if it wants to be a W or an M this month.

Binocular Sights (7 to 10 power): The must see binocular sights for a clear December night are: The Pleiades star cluster in Taurus, the Double Cluster in Perseus, the Orion Nebula in the center of his sword, also try to find all three open star clusters in the constellation Auriga; M36, 37, and 38. Hope for the perfect night to view the Andromeda Galaxy. Finally, if you just like to “look at stars” with your binoculars, there are two great places to visit this month. First scan the “V” asterism in Taurus (between Orion and the Pleiades). This area is filled with stars associated with a broad open star cluster, the Hyades. The Hyades is the closest star cluster to Earth, and contains 300-400 main stars. Next visit the constellation Perseus high in the northeast. The brightest star in Perseus is Mirfak. Using Mirfak as your central point, scan the sky around this star, and you will find a wonderful gathering of young stars. This area is known as the Perseus Association; enjoy.

Telescope Sights (60-100mm): The planet Mercury; AFTER SUNSET! Aim at the Orion Nebula/M42, which appears to be the center star of Orion’s sword. Above 25 power, you should be able to locate four young stars that were born in this star nursery. These stars are known as the Trapezium, because they form a tiny trapezoid.