by C. Zaitz
For the past weeks I’ve mentioned that Jupiter is the only planet visible in the evening sky, and that you can “catch a glimpse” of it after sunset. However, that’s been rather lame advice. There’s much more fun to be had with a telescope. But telescopes are expensive, so this is a great time of year to find your local amateur astronomy club and attend an evening observing session, or “star party.” We are lucky to have several fine clubs in our area. The clubs are friendly, social, and have access to dark observing spots, plus they always bring big telescopes so you can enjoy the benefits of Aperture!
Aperture is what matters in a telescope. Even though the word means “opening,” it refers to the size of the light gathering mechanism within. In most popular telescopes, it’s a mirror. Originally it was a glass lens, but glass is heavy and fragile, prone to cracking and chipping. Mirrors are still glass, but not solid glass, and only one side has to be ground to perfection, rather than both sides of a lens. You can make mirrors pretty big, and the bigger the mirror, the better the telescope.
Why is bigger better? What are we trying to do with a telescope? Many people think that telescopes “magnify” light, but it might be better to say they “collect” light. Objects in the night sky are very far away. By the time light from a distant object reaches us, it’s pretty faint and spread out. When you collect rain water, you use a big tarp and funnel it into a barrel. The bigger the tarp, the more drops you can collect. With telescopes, the mirror is the tarp. The bigger the mirror, the more photons of light it collects, and the better you can funnel or focus the light to see distant objects. The cool thing is that if you double the aperture on a telescope, you quadruple the amount of light you can gather.
I have just come into some aperture. I have had a 4 inch Astroscan telescope that my parents bought when I was young. Recently they arrived for a week at the cottage bearing gifts. For my husband, a beautiful set of hand made saw horses. For me, an 8 inch LX90 Meade Schmidt-Cassegrain telescope. I was flabbergasted. I named it Carl.
Through the Astroscan, Jupiter looked like a big dot with four tiny specks around it. Through Carl, Jupiter looked like Jupiter with its four largest moons dancing around it. It was impressive. We had a family star party: we toasted marshmallows in the campfire and toured the night sky. We saw M13, the globular cluster in Hercules, the Ring Nebula in Lyra, and the Andromeda galaxy, over 2,000,000 light years away. It was very cool.
Sure there are bigger, more expensive telescopes out there, but Carl and I will have lots of fun together touring the dark skies of Port Austin. Everyone’s experience of the night sky is special, no matter if you own a really big ‘scope or just go out in the backyard with binoculars and locate Jupiter in the western sky. The key is to do it, to give yourself and anyone you can drag out with you the experience of remembering how big and beautiful the universe is. But if you can borrow someone’s aperture AND get a cool explanation of what you’re looking at, well, that’s a Star Party!
Until next week, my friends, enjoy the view!
No comments:
Post a Comment