TELESCOPE FAQ Part 1: “How far can this telescope see?”
by adminWhen we help customers choose a new telescope they naturally have a lot of questions about the telescope they plan to buy. We’ve already done a Telescope Buyer’s Guide
but that doesn’t answer a lot of these questions directly. This entry hopes to be the first part of a series where we answer and cover some of the harder questions people have about telescopes.
Frequent Question #1: “How far can you see with this telescope?”
Answer: Some questions about telescopes have very simple answers: This comes with two eyepieces, it has a 6 inch mirror, and so on. But this question doesn’t really have a good answer. The reason for that is that not only objects are as bright as each other, and being further away in space doesn’t automatically mean harder to see.
Let me put it this way by comparing two objects: Pluto is considered to be within our Solar System. It is on average (it has a tricky orbit) a mere 4.1 billion, or 4,100,000,000 miles from the earth at its closest. Cosmically speaking that is pretty darn close! And yet despite this even the Hubble Space Telescope has trouble getting a decent picture of Pluto. Not surprising as it is very faint and not very large. Smaller telescopes can ’see’ Pluto, but it looks like little more than a point of light with no detail at all.
Now let us consider the Andromeda Galaxy. Firs of all it is a galaxy, so it is much large, but it is also 2.5 million light years from Earth. To put that in miles, it is 14,696,563,432,959,020,000 miles from Earth. That means it is 3,584,527,670 times as far away Earth than Pluto. Yet because it is a large object, and rather bright (galaxies are groupings of stars after all) even a small telescope should be able to see it, and with some pretty good detail to boot!
The proper question to ask would really be ‘what can I see with this telescope’. The answer we give should apply to any decent telescope, large or small:
Any telescope should be able to see: The Moon, most of the planets, and a good number of the brighter deep sky objects (nebulea, galaxies, etc.). More powerful (larger) telescopes will get better images of these things, with more detail and objects will appear brighter - and none of that is dependent on ‘how far away’ those things are.
If you enjoyed this post, make sure you subscribe to my RSS feed!
[…] Continuing our series of Frequently asked questions we get about telescopes at the store we continue from part 1 […]