How far can I see with a telescope?

The farthest you can see in the sky with your telescope will depend on its ability to gather light and where you observe.

The most distant objects visible with amateur-sized telescopes are faint galaxies and the brightest quasars. They will be brighter and easier to see in a scope that gathers more light and has a greater magnitude limit (two topics discussed elsewhere in the Knowledgebase). Here bigger is better and a larger aperture scope will see more remote objects.

Location is also important. Even with a big scope, you’ll see fainter, deeper and farther out into the universe from an isolated dark-sky site than from the heart of a megalopolis.

For example: quasars are all very faint as seen from the earth. The brightest one is 3C 273 in Virgo. It is magnitude 12.9. A good 4 in scope is capable of seeing it in dark-sky conditions. You’ll need a larger scope to see it at all from a city.

This quasar is an active galactic nucleus that is located about 2.6 billion light-years from the earth. For more information on 3C 273, go to the SEDS web page.

Updated 12/27/13