Astronomy Buff

Through Your Telescope: Orion Nebula

by Tony on December 29th, 2007

I know everyone got a new telescope for Christmas this year, so I thought I’d write up a series of posts on what you can expect things to look like through your new time-sink.

Using the magic of Stellarium, I thought I’d show you how some of the more common objects will look through your eyepiece. A couple of caveats: Stellarium shows images taken through the Hubble Space Telescope when you zoom in to look at them, so you won’t see this kind of detail with your naked eye, you’ll need some kind of CCD camera for that. Here’s an observing trick: your peripheral vision is better at picking out detail at low light levels, try looking off to one side and your eye will pick out more stuff.

What Stellarium DOES do a good job of though, is showing the relative brightness of the objects you’ll see. Just understand that the level of detail you see on a given night will be determined by your focus, the alignment and quality of your optics and the seeing conditions where you are.

The images shown below are flipped according to the type of optics. In a reflecting telescope, things are flipped horizontally and vertical (if you are using a right-angle prism to turn the eyepiece up).

Click on any of the images to see a bigger one.

First up, the Orion Nebula. Everyone with a new telescope should check this one out first. It’s big, easy to find and high in the sky during the winter:

In the northern hemisphere, Orion is high in the sky during winter. Look in the sword for the Great Nebula (outlined in the box).

Here’s what the Orion Nebula looks like from an Edmund Astroscan-type telescope (4 inch mirror, 445 mm focal length, 28mm eyepiece that came with it):

Orion Nebula through an Astroscan. Roughly 3 degree field of view at 16x

Here it is through a typical Dobsonian (8 inch mirror, 1220mm focal length, 26mm eyepiece):

Orion Nebula through a typical Dobsonian (e.g. Lightbridge). 1.13 degree field of view, at 46x.

Finally, a higher-end scope like a 10-inch LX200 (2000mm focal length, 26mm eyepiece):

Orion Nebula through an LX200-type scope. 0.7 degree field of view at 77x.

You can see that the image is slightly brighter as you go to the larger diameter scopes, you also get a narrower field of view and higher magnification because of the longer focal lengths.

Remember, your results will vary depending on the conditions outlined above, but you get the idea. Bigger scope = brighter image, more detail, higher mags and all around better image.

Next up: Mars, since it is close to opposition and near the Orion Nebula.

Have fun with your new toy!

Technorati Tags: observing, orion nebula, telescopes

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