A black hole is a place in space where gravity pulls so much that even light can not get out. The gravity is so strong because matter has been squeezed into a tiny space. This can happen when a star is dying. Because no light can get out, people can't see black holes. They are invisible. Space telescopes with special tools can help find black holes. The special tools can see how stars that are very close to black holes act differently than other stars. Black holes can be big or small. Scientists think the smallest black holes are as small as just one atom. These black holes are very tiny but have the mass of a large mountain. Mass is the amount of matter, or "stuff," in an object. The Event Horizon Telescope has released the first direct image of a black hole in april 2019. This black hole lurks in the centre of a nearby galaxy called M87. This historic image shows a ring of light coming from the gas falling into the black hole.The EHT has imaged the silhouette or shadow of the black hole at the centre of M87, a galaxy 55 million light years from us. To make this image, astronomers combined data from 8 different telescopes across the world in an experiment in April 2017. The data was taken at a frequency of 230 GHz, or a wavelength of 1.3 mm. Using this, astronomers have formed an image of the black hole for the first time. The event horizon of a black hole is the ultimate boundary. Nothing from within it can escape out. The ring of fire in the EHT image is light from the gas falling into the event horizon, whose shadow is the dark hole in the centre. The exact shape of the ring is due to the way the incredible gravity of the black hole bends the light around it, and the incredible speed at which the gas is travelling is why the ring is not uniform in brightness.
https://www.bbc.co.uk/programmes/articles/4brTN2gszzhFFSGWddZCyyH/a-mini-mot-for-your-cervix Black hole explored.
