Moon/Venus/Jupiter

Monday evening, December 1, the sky will present everyone with a spectacular conjunction (
http://news.yahoo.com/s/space/20081128/sc_space/spectacularskyscenemondayevening) of the Moon, Venus, and Jupiter. No telescope needed but binoculars will make it even more impressive. The three objects will appear extremely close together shortly after sunset but in reality they are very far apart in space. The moon will only be just over 251,000 miles away while Venus will be a little over 93 MILLION miles away, and Jupiter, almost on the other side of the sun from us, will be 540.3 million miles away. The best to observe this about 1/4 to 1/2 an hour after sunset. They will remain visible until they set, Venus and Jupiter around 7:40pm local time and the Moon around 8:00. The later you look, of course, the lower in the sky they will be. The most beautiful time is shortly after sunset when the sky still retains a little blue color from the light of the Sun below the horizon.

Happy viewing!

Talk About Tailored Ads!

I just noticed something interesting about the ability of ads to match the content of a page. I was reviewing my blogs on Astronomy to determine what I should start working on for my next endeavor. I was surprised when the ad banner at the top of the page showed the following!

Meade LX 200 Telescope
Premier Meade Telescope Dealer Fast Shipping. Helpful Service.
www.astronomics.com

Orion Telescopes
Factory-direct prices and same-day shipping on scopes and accessories!
www.Telescope.com/Orion

Vixen Telescope Sale
Vixen Refractors, equatorial mounts Large Vixen Selection, Low Prices!
www.optcorp.com/Vixen-Products

Talk about targeted marketing! Not only that, but my first telescope was purchased from Astronomics, I have an Orion telescope that I got directly from Orion (telescope.com), and my favorite dealer is optcorp (Oceanside Photo and Telescope)!

Astronomical Observing 101 (or before) Part 4

Well, it's been a while (like almost a month), but then again, no one has complained. So here we go with telescopes. Although the tube (actual telescope), is very important, the mount is equally important. They fall into two basic categories, altazimuth and equatorial.

Altazimuth allow changes in altitude (up and down) and azimuth (around and around) similar to a camera tripod. One very popular mount is called the Dobsonian named after a California amateur astronomer, John Dobson.

Equatorial mounts allow a smooth tracking of objects as the earth rotates beneath a stationary sky. (I know it looks like the sky is moving, but it really is the earth). These types of mounts allow long exposures of objects with a camera when equipped with a motorized drive (or very steady hand on a manual control).

Either type of mount can optionally be found with "GOTO" capabilities. This means that, after a proper setup, a computer can automatically point the telescope to a specific object (star, nebula, planet, cluster, galaxy, etc.).

Please note that the recommendations are not all inclusive! I own two Orion scopes and two Meade scopes. That doesn't mean that other manufacturers are worse, just that I've come to like what I have. Celestron (now an arm of Meade, or vice versa), Sky-Watcher USA, Tele Vue, Astro-Tech, and others make good quality scopes to fit a lot preferences.

Newtonian Telescopes

Least expensive for the amount of light gathering primary mirror, these can be found in sizes from around 4.5 inches up to 17.5 inches! Prices range from as little as $180 to as much as $4,000. Mounts are generally altazimuth but not in all cases. In addition, some are offered on "GOTO" mounts.

For beginning amateur astronomers, a small Newtonian on either kind of mount is a great way to start. Orion Telescopes (at www.oriontelescopes.com) makes some really nice ones, affordably priced. One that was tested by Sky and Telescope in their September, 2008 issue was a 6" telescope called the StarBlast 6 with two decent eyepieces on a Dobsonian mount. The included eyepieces are 25mm (30x) and 10mm (75x). A great starter at a reasonable price, $250.  Edited to add cost!!!

If you want something cheaper, then look into an 4.5" from Orion, the SkyQuest XT 4.5" Dobsonian at $190. I wouldn't go any smaller than this and don't REALLY recommend it since with the smaller aperture, it won't give you the views that you can get with the larger scope.

Schmidt-Cassegrain

These are generally larger scopes but easily transported due to the "folded" light path used. They are often fairly heavy (around 70-80 lbs or more with tripod), especially when mounted on their tripods. They generally range in size from 8" to 14" and from a $1,000 on up and can be found on both altazimuth and equatorial mounts. Most are "GOTO" scopes and the ones on equatorial mounts are good for photography.

Celestron and Meade are the primary manufacturers of these. I have an old Meade LX-50, 8" that I added "GOTO" capability to and got the equatorial mount for it. Today, the LX-90 is comparable and goes for about $2,100.

Maksutov-Cassegrain

These are generally compact, smaller scopes (about 15 lbs without tripod) primarily manufactured by Meade, Celestron, and Orion. For a while, the most popular were the Meade ETX series although the other ones have made inroads in there sales. The original ETX was a 90mm version but a 102mm and 125mm were added. Now they range from 90mm to 180mm. One of the earliest telescopes of this type was the Questar 90mm, which currently start around $4,000. Others are priced from around $400-900 on up.

I have a Meade ETX-125 that currently goes for about $900 on sale (list $1800).

There are a lot places to buy these and the number of scopes available is mind boggling. I generally buy from OPT (Oceanside Photo and Telescope in Oceanside, CA, www.optcorp.com) because I have had good luck on prices and they have given me excellent service. Orion (OrionTelescopes.com) sells direct (I have two of their scopes) and have been very reliable. My first Meade was purchased from Astronomics (Norman, OK, www.astronomics.com). They gave good service and reasonable prices but I still prefer OPT. Some of the other big names are Scope City, Woodland Hills, and Wolf Camera.

The important thing is to shop around, get familiar with the type of scope you want, and who can give you the best price with good service.

Next up: Accessories - You can and probably will spend more on accessories than on your telescopes. What are they and what are they good for? Stay tuned for a future installment!

Some more personal stuff.

As some of you know from posts in our clan forum and in "Off Topic", my great nephew Zachary (3 years old, I have found out, not 4) had to have brain surgery for Chiari Malformation (http://www.2old2play.com/modules.php?name=Forums&file=viewtopic&t=47627&highlight=chiari). Well, he had the surgery on Monday, September 29th and I'm extremely happy to say that it appears to be successful. After a few days of concern since he wouldn't eat and was suffering from vomiting (a common side effect), we got a call today from his dad to let us know that they have released him from the hospital in San Antonio, Texas. They will start the long drive back to Rockford, IL soon. WIth the after effects of the surgery, they didn't want to take him on the plane. Thanks to all who prayed and kept him in their thoughts. Our families appreciate the concern and support of everyone here.

Astronomical Observing 101 (or before) Part 3

OK, so I lied! I had ended the last blog with "Next time I'll look at the 3 types of reflectors and give some examples of the prices of some popular models (two of which I have plus one that is on loan to my brother)."

Instead, I find I need to cover just a little bit more on terminology and on the types of telescopes.

Refractors have an Objective lens (the big one) and an eyepiece (or ocular). Reflectors have a primary mirror (the big one) and either a secondary mirror or a diagonal, and the eyepiece. The size of the objective lens or the primary mirror is known as the aperture. The focus point of lens/mirror is based on the amount of curvature of the lens/mirror(s). The distance from the lens/mirror/eyepiece that the image comes to a focal point is known as the focal length. This is important when calculating the magnification achieved with certain telescope/eyepiece combinations. The focal length divided by the aperture is known as the focal ratio and for a 150mm telescope with a focal length of 1200 would be shown as having a focal ratio of f/8. If you are into photography, this will seem familiar as camera lenses have a focal ratio assigned to them in the same way and it defines how "fast" the lens is. The lower the number, the faster the lens and thus requires a faster shutter speed to properly expose the picture. It has similar ramifications in doing astrophotography!

When you look at the design of reflector telescopes, you will see that the effective aperture usually is not the same as the diameter of the primary mirror. Following is a chart from "Norton's Star Atlas and Reference Handbook" that I referenced in my first Astronomy blog.

This diagram shows the focal point and not the eyepiece. It must be understood that eyepiece is located just beyond the focal point and in case you can't read the fine print, here is the explanation:

Different types of telescopes. For telescopes of similar apertures, the path of light ray from a celestial object to the focus F is shown through (a) a refractor, (b) a Newtonian, (c) a Cassegrain, (d) a Cassegrain-coude', (e) a Schmidt-Cassegrain, and (f) a Maksutov-Cassegrain.

Note that I did not mention the Cassegrain and Cassagrain-coude' earlier because they are rarely found. There is actually a rare 7th type which tilts the primary mirror of the Newtonian, reflects the image off a mirror which is outside the the path of the incoming light, and passes it through lenses that correct the astigmatism caused by the tilt of the primary. Although more difficult make, it offers brighter images than possible through the other reflectors for the same size primary mirror. This is known as a tilted-component telescope. With the exception of the this last type, you will notice that the incoming light has part of its path blocked by a diagonal or mirror, and in the case of several of them, a hole in the primary mirror. This is what reduces the physical aperture to an effective aperture that may be as little as 60-70% of the actual one.

One last term that you may come across is the catadioptric telescope which is a generic term for the telescopes like the Schmidt-Cassegrain and Maksutov-Cassegrain.

The last item to cover in this blog is magnification. Eyepieces have their own focal length and when used in conjunction with a telescope with its own focal length, defines the magnification achieved. Magnification is determined by dividing the focal length of the telescope by the focal length of the eyepiece. Here is a table of the magnifications from my eyepieces and telescopes. There is an additional lens that can be used called a Barlow which doubles the effective magnification, hence the nnnn.x2 columns.

Next time I'll REALLY look at the 3 types of reflectors and give some examples of the prices of some popular models (two of which I have plus one that is on loan to my brother).