If you are new to the world of astronomy then you have picked a very good time to get involved. Never before has there been such an array of astronomical telescopes so widely available.
Of course, this can be a little daunting to the uninitiated, but learning about telescopes is just part of the fun? There are a few basic things to know about telescopes, and the most important feature of any telescope is its aperture. The aperture is the diameter of the main optical component, be it a lens or mirror.
The aperture determines the telescope’s ability to gather light and to see an image in fine detail (resolving). So what does all this mean? Well, with a six-inch telescope you will be able to see craters on the moon that are only a mile wide.
However, those same craters would appear twice as large in a three-inch scope. Okay..? Now point those same two astronomical telescopes toward a faint galaxy on a moonless night and see what happens. Compared to the three-inch scope, The six-inch telescope will gather four times the amount of light instead of twice as much, making the faint galaxy appear four times brighter in the larger scope.
Why so? Because the six-inch telescope has four times the area for collecting light than the three-inch scope. Confused? You will be…but not for long.