What does the X-ray Universe look like?
![](https://www.nasa.gov/wp-content/uploads/2023/03/3c58_xray_optical.jpg)
Only the hottest cosmological objects and the most energetic events generate X-rays. Studying them teaches astronomers about the violent Universe, where stars explode, black holes devour matter and galaxies collide.
![](https://cdn.spacetelescope.org/archives/images/screen/opo1025a.jpg)
The hottest objects and the most violent events in the Universe produce high-energy X-rays: solar flares, neutron stars, cosmic shock waves, extremely hot gas in galaxy clusters, colliding galaxies and matter spiralling into black holes. The human eye cannot see X-rays. In fact, your retina would be destroyed by this energetic cosmic radiation. Astronomers use representative colours to create images of the X-ray Universe, based on observations by Earth-orbiting space telescopes.
Our ears cannot hear the high pitch of a dog whistle. In the same way, our eyes cannot see X-rays coming from space. The pictures here show what you would see if you had X-ray vision.