For the past few days, I’ve done a lot of talking about differences between types of telescopes and mounting systems. On occasion, I’ve mentioned some of their parts, though I haven’t focused on that.
Today, I will.
This post is meant to be a brief overview of differences between telescopes and their parts. If you want some more in-depth explanations, I’ll link back to those I’ve already written.
In the image above, you see just a few different examples of telescopes. And just in this image, they range far and wide. Most stand on tripods, but some don’t. I can see two different telescope shapes. Some have the eyepiece in different places.
There are more variations of telescopes than are shown here.
So climb on board…I’m about to take you on a telescope tour!
Okay, so maybe I sort of gave it away in the post title…
I know what you’re about to say next. Why are we looking at a mount? What’s so special about a mount—isn’t the telescope itself more important?
And the fact is…I know where you’re going with that. The telescope is important, and without it, the mount would have no purpose. But without the mount, the telescope would be lost—it would have power, but nothing to do.
When you look up at the night sky on a clear, dark night, it seems as if the stars are glittering like bright thumbtacks on a great canvas above you. (You can get a similar effect–with less light pollution–from a planetarium like the one above!)
In reality, space is not like a canvas, and stars are not like thumbtacks. It would be more accurate to describe us Earthlings as floating in a vast, cosmic ocean.
Astronomers know this. But still, it’s helpful to map the sky in exactly the way it appears to us: as a sphere around the Earth. And so we use a model called the celestial sphere.
Telescopes operate solely based on the celestial sphere: the mechanism that aims the telescope doesn’t need to know anything about how far away an object actually is in the cosmic sea, just where it is in the sky.
That makes the celestial sphere a useful reference tool. Researchers need to communicate with telescope operators and say, “Let’s look over there now.”
And so, everything is mapped on a spherical model that pretends the night sky is a finite globe, inside which the Earth hovers like a bubble.