What could be more terrifying than a star a million times larger than the Sun? An invisible point capable of absorbing even light. These are black holes—regions of space where gravity is so strong that nothing can escape, even at the speed of light. At the center of our galaxy, the Milky Way, lies Sagittarius A*. Its mass is 4.3 million times that of the Sun and it is located 26,000 light-years from Earth. It is our closest cosmic giant. But Messier 87*, the first black hole photographed in 2019 by the Event Horizon Telescope project, is 6.5 billion times more massive than the Sun! Its event horizon is enormous, exceeding the size of our Solar System. How do they form? Stellar black holes form when massive stars, more than 20 solar masses, collapse after a supernova explosion. This is a true cosmic cataclysm. But black holes aren't just cosmic monsters. They play a key role in the formation of galaxies, including the Milky Way. Continue exploring these mysterious objects in the Universe!