What is X-ray Astronomy?
X-ray astronomy refers to observations in space at high energy wavelengths.X-rays contain approximately 10,000 times as much energy as normal light waves, which are the waves we see with our eyes. Both x-rays and normal light waves are electromagnetic waves. for which more information may be found at this link: Electromagnetic Waves.
X-rays have been observed coming from space from discrete sources. This radiation (x-rays) is absorbed by Earth’s atmosphere, and therefore requires an above-the-atmosphere satellite to observed them. That is why X-ray Astronomy is a relatively new science, because substantial observations did not begin until the Uhuru satellite was launched in 1970.