Question

What are x-ray telescopes useful for?

Answer 1

Because X-rays cannot penetrate Earth's atmosphere.

Explanation:

As X-rays cannot penetrate Earth's atmosphere therefore they are essentially invisible to the naked eye and to the largest ground based telescopes, even if you place telescopes on mountain tops you would not be able to detect x-rays. So X-ray telescopes are specially designed to detect X-rays are placed outside the Earth's atmosphere i.e. in Space so, that they can detect these rays. One example of X-ray Telescope is the Chandra X-ray Laboratory put in Orbit by NASA.