What is an Earth telescope?

Answer 1

An Earth-bound telescope is merely a telescope located on Earth.

This term is used to distinguish all of our normal telescopes on Earth from space telescopes or orbiting telescopes. The Hubble space telescope is the most famous space telescope, but there are many dozens of telescopes orbiting Earth which look at Earth or the Sun or other objects in space.

Obviously, it is easier to construct an Earth-bound telescope and they can be bigger since getting a telescope into space requires a rocket and a lot more engineering and money.

Space telescopes have the advantage of being outside the atmosphere and thus no atmosphere to diminish the quality of the image. For infrared telescopes there is the advantage of being in the cold environment of space where the interference from radiations of hot objects on Earth is absent. On the other hand, space telescopes are hard to repair and you can't really be there to look through them.