November 2012

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 November 13th.  For November, your best viewing nights will be from November 3rd to the 17th. The Star chart below is set for Florence, SC on November 15that 9 pm.

Note: Each November I will feature my telescope purchasing column. Of course any timely astronomy sights will also be included at the end of the column.

So you want to buy a telescope:
Every year a telescope appears on someone’s Christmas list. If you are considering your first purchase of a telescope, the following information may help you with your selection.

First suggestion:  Never buy a telescope from a department store. This suggestion also pertains to TV shopping networks. If the telescope box, or sales sign or salesperson mentions power (usually something above 200 or 300 power, then stay away! Good telescopes are defined by their light gathering ability, not by power.  In addition, the quality of the lenses is usually poor, and the tripod mounts can be quite wobbly. The shortcomings of these “bargain” telescopes my may result in frustration when using them, and may discourage instead of encourage your interest in astronomy.

So the solution is to purchase a telescope from a telescope store, most of which are online. One well-known dealer is Orion telescopes found at telescope.com, others are Meade and Celestron. If you require other sources of telescopes, go to your local bookstore and buy a copy of either “Astronomy” or “Sky and Telescope,” magazine, and check their advertisements.

So now that you know where to buy, the harder problem is what to buy. There are three basic types of telescopes: Refractors, Newtonian reflectors, and Schmidt-Cassegrain reflectors. You should consider a starting price of about $200, with a better starting amount being $300.

A refractor is what one might consider a traditional shaped telescope, a long thin tube with a lens (objective) in front to gather light, and another lens (eyepiece) in the back. They are fine telescopes for viewing the moon, planets and double stars and are often bought as “starter scopes.” However, they usually don’t have sufficient light gathering ability to give good viewing of galaxies and nebulas, unless you purchase expensive high-end refractors.

A Newtonian reflector uses a mirror to gather light instead of a lens.  The telescope consists of a hollow tube open at the top with the viewing eyepiece near the top at a right angle to the tube. Amateur scopes can have as small as a 3-inch diameter mirror, but basic reflectors usually range in size from 6 to 10 inch diameter mirror. Because of their large light gathering ability, they can be used for a large range of astronomical targets, including galaxies and nebulae.

A second class of reflectors is the Dobsonian reflector, usually called a Dob.  The Dob was invented by John Dobson, and is a simple reflector that is placed in a mount on the ground, see image below.

Dobs are easy to use and quite inexpensive versus light gathering ability. Bottom line is that Dobs are known for giving the best telescope for your money. Some other considerations are, that they can be bulky to transport, and do need periodic fine adjustments to the main mirror, called collimation. Laser collimators are available to make this job easy.

Schmidt-Cassegrain reflectors were designed to give the benefits of a reflector, but minimizing the length. These telescopes tend to be, on average, the most expensive of the three telescopes types. Also of the three types, these are the telescopes that most likely come equipped with computerized finders, known as GoTo scopes. A GoTo attachment will allow you to enter in on a keypad any celestial object, and the telescope will automatically find it for you if it is visible on that particular night. Note: GoTo systems are available for other reflectors and also for refractors. I do not personally favor GoTo systems because I feel that the best way to find your way around the night sky is to find your target objects on your own.

Do you really need a telescope? If you are serious about a hobby in astronomy, it might be best if you put a pair of binoculars on your Christmas list this year, and buy the telescope next year. Reasons:  Binoculars are cheaper, most ranging between $80 and $200.  Binoculars will allow you to see a large region of the sky, and right side up! Binoculars can serve for other uses such as bird watching or sporting events. For simple astronomy, most people prefer 7 X 50 binoculars. If you get the binocular astronomy bug, you might someday upgrade to “big binoculars.” Some are shown below; I happen to own the one shown on the far right side of the photo, and it can see the Saturn’s rings!

My recommendations: If you want to start a serious venture into amateur astronomy, begin by buying a pair of binoculars, star charts, books, and astronomy software. If you must have a telescope this year, start with a Dob, minimum 6 inch, preferred 8 inch.

Naked Eye Sights:  The Leonids meteor shower peaks in the early morning hours of November 17th. The sky will be dark, but it is not expected to be a good shower.

Binocular Sights (7 to 10 power):  Jupiter rises in the east this month. Check out Jupiter’s moons.  Move to the right of Jupiter to see the open cluster, Hyades.

Telescope Sights (60-100mm):  The return of the planet Jupiter offers a great sight.  Try to see the Jupiter’s atmospheric bands of clouds.

 

See you next month!

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