December 2017

                              Tony Martinez

Each month I will describe sights of interest in the night skies of South Carolina. These sights will be broken down into four sections; what you can see with the naked eye, with binoculars, with a small refracting telescope and with a Dobsonian reflector. 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 18th. For December, your best viewing nights will be from December 7th to the 22nd. The Star chart below is set for Florence, SC on December 15th at 9 pm. Note: A table of contents for earlier columns is located in the February 2016 column.

Correction Note: For the last several months, the location of my table of contents page, shown in the introduction paragraph, was incorrect. The correct location of my table of contents page is in the February 2016 column.

Note: Usually each November I feature my telescope purchasing column. It was postponed until December this year.

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, 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, these department store scopes usually have poor quality lenses and wobbly tripod mounts. The short comings of these “bargain” telescopes my may result in frustration when using them, and therefore may discourage instead of encourage your new 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. In addition, check out sources in “Astronomy” or “Sky and Telescope,” magazines.

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 mirrors. Because of their large light gathering ability, they can be used for a large range of astronomical targets, including galaxies and nebulae.

Another type of Newtonian 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; the larger ones can be bulky to transport, and they do need periodic fine adjustments to re-align the main mirror, called collimation. Laser collimators are available to make this job easy.  I collimate our Dob every time we use it; this adjustment takes me only about 1-2 minutes.

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 to come equipped with a GoTo contoller which allows you to enter in on a keypad any celestial object, and the telescope will automatically find it for you. I do not personally favor GoTo systems because I feel that the best way to learn the night sky is to find your target objects using charts or astronomy computer programs.

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 or 10 X 50 mm binoculars. If you get the binocular astronomy bug, you might someday upgrade to “big binoculars”; some of these are shown below. I own the gold colored one shown on the far right side of the photo, and with it, I can see Saturn’s rings!

To sum up 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: Geminids meteor shower peaks on morning 14th, on a Moonless night.

Binocular Sights (7 to 10 power): The Pleiades, the Double Cluster and the Coathanger asterism.

Telescope Sights (60-100mm): The double star Albireo.

Dobsonian telescope (6 -8 inch): The Ring Nebula in Lyra, M57.

See you next year!

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