Many have wondered whether an astronaut can enter a black hole. Now it appears astronauts can, but it will be the loneliest journey ever undertaken. Leo and Shanshan Rodriquez, both assistant professors of physics at Grinnell College compared two types of black holes, stellar-sized and supermassive.
Stellar-sized black holes are roughly the size of the Sun while supermassive black holes can have a mass equal to four million Sun's. Both these black holes have event horizon. It is the boundary line, the point of no return. When anyone crosses the event horizon, the massive gravitational pull of the black hole takes over.
It's not a good idea to try to enter stellar sized black hole as its event horizon is just a few kilometres long and closer to the centre of the black hole. If an astronaut enters such a black hole he will undergo what's known as Spaghettification. All the atoms of his body will be torn apart. Contrast this with a supermassive black hole like the one at the centre of the milky way galaxy. Such black holes have event horizon stretching to millions of kilometres.
The gravitational pull in this part in case of supermassive black holes is not as extreme as that in stellar-sized black holes. The researchers said that the black hole needs to be isolated from the space around it in order for an astronaut to safely enter it. But even if that is the case, imagine the lonely journey that astronaut would undertake while trying to cross millions of kilometres of event horizon. It would be the loneliest journey in human history indeed.