Department Store Telescopes

Have you been looking up at the stars recently and thought about purchasing your own backyard telescope? Have your kids put telescope on their holiday wish list? Do you want to learn how to take photos of astronomical objects? If you answered yes to any of the above questions, then I have one piece of advice for you: don't buy a department store telescope! Yes they are inexpensive and promise to show you beautiful images of the moon and planets, but they are more hassle than they are worth. I've had many friends and family members purchase these telescopes, struggle with their kids for hours in the back yard trying to see something with it, only to package it up the next day and toss it or re-sell it. Why are these telescopes so "bad"? Well, bad is really a poor choice of words. They are usually refracting telescopes designed to look at large bright objects, and they do a good job of that. One of the main complaints I get from people is that the images look blurry, so they try to magnify the image by inserting a higher magnification eyepiece, in hopes of getting a clearer view. What they don't realize is that magnification only blurs the image more. Theses telescope are small (usually a few inches wide) and only collect so much light. Magnifying that light is not going to make things more clear or brighter, its going to enlarge a small dim region, and likely make it look darker than before. The image you see will never look like the one on the box, guaranteed. The second complaint I hear is that they are difficult to "point", as in, even if you think you have it aimed at the moon, you can't see anything. This is a problem with all small, non-computerized telescopes, and can get really frustrating really quickly. My best advice here is to be patient and try to learn your way around the sky. Point the telescope towards the moon and practice lining it up by looking at the stars with your eyes, then through the telescope, and adjusting as necessary. Practice makes perfect with this. Lastly, you must remember that we live on a moving rotating sphere, and therefore, when you point your telescope at an object, it will only stay in your field of view for a short time before you have to readjust. This is true for all telescopes, unless you have one that "tracks".

So, I very much encourage you to buy a backyard telescope, and I don't want a bad experience with a cheap scope to detour your love of astronomy! You can still acquire an excellent, easy to use telescope for a few hundred dollars. Check out websites like http://www.celestron.com/ and http://www.meade.com/ and do your research! Ask friends in a local astronomy club what they suggest, or attend a telescope buying seminar. Often, local museums will offer workshops on how to purchase and operate basic telescopes for the beginner. Check these out, avoid the department store telescopes, and I promise you will love your new investment. Clear Skies!

A "Not So Amateur" Image of the Disk Around Beta Pictoris

We've discussed circumstellar disks around young stars multiple times in this blog, but we haven't discussed how they are observed. Circumstellar disks are best visible at infrared and optical wavelengths. This is because the disks are made of dust and gas, which reflect optical starlight and emit thermal infrared light. Astronomers have used telescopes such as Hubble (optical) and Spitzer (infrared) to image  many disks of young stars, but you don't necessarily need a space telescope to see these disks.  An amateur astronomer named Ralf Olsen proved this by imaging the disk around the nearby young star Beta Pictoris! Armed with his backyard 10inch telescope, a PC webcam and no filters, Olsen was able to image the disk of Beta Pictoris by following a procedure outlined in a 1993 paper by Lecavelier Des Etangs and collaborators. Basically, Olsen imaged Beta Pictoris and a very similar star called Alpha Pictoris, then subtracted the Alpha image from the Beta. Since the stars have similar properties, subtracting the images effectively erased the light of Beta Pictoris, making its disk visible. The image below is the final result from Olsen.

 

The black circle is where Beta Pictoris was removed in the image, and its disk is the extended white region near the star that the dotted lines point to. It's really amazing what an amateur astronomer can do with a basic telescope! Olsen is living proof that you don't need to be a rocket scientist to understand, and even contribute research to the field of astronomy!

Image Credit: Rolf Olsen

http://www.pbase.com/rolfolsen/image/139722640/original