The Cherenkov Telescope Array, in short CTA, is a ground-based observatory for gamma rays.
Its telescopes are much more sensitive than those of the previous generation and are designed to detect high-energy particles.
Thanks to its large extension, it will be able to detect a wider range of rays and it will allow scientists to study even the rarer particles that arrive on earth.
But how do these telescopes work?
They don't actually measure directly the gamma rays that arrive from the far regions of the cosmos. In fact, those don't make it all the way to the ground trough the atmosphere: rather they interact with it and create a cascade of subatomic particles, known as particles showers.
Even thought in the vacuum nothing can travel faster than light, in the atmosphere these high-energy particles can travel faster than light in the air, creating a blue flash called Cherenkov Light, which the CTA's telescopes measure.
From those only, scientist are able to reconstruct the particle that generated the particles shower in the first place, and thus the nature of these mysterious rays that bring information about the most catastrophic phenomena in our universe.