How bright is a quasar? Imagine hovering over a large city like Los Angeles at night. And if they are in their active quasar phase, you’ll be blasted by high-energy radiation. If you get too close, the enormous gravity will suck you in. Massive black holes are dangerous in two ways. These black holes are dark most of the time, but when their gravity pulls in nearby stars and gas, they flare into intense activity and pump out a huge amount of radiation. It’s over a thousand times bigger than the black hole in our galaxy, whose discoverers snagged this year’s Nobel Prize. Just last year, astronomers published the first-ever picture of a black hole and its event horizon, a 7-billion-solar-mass beast at the center of the M87 elliptical galaxy. That’s like the difference between an apple and the Great Pyramid of Giza. Nature knows how to make black holes over a staggering range of masses, from star corpses a few times the mass of the Sun to monsters tens of billions of times more massive. Over the past 30 years, observations with the Hubble Space Telescope have shown that all galaxies have black holes at their centers. National Science Foundation via Getty Images A hungry beast in every galaxy The black hole is outlined by emission from hot gas swirling around it under the influence of strong gravity near its event horizon. As the poet Dante described the words over the gates of hell in his poem Divine Comedy: Abandon hope, all ye who enter here.Ī photograph of a black hole at the center of galaxy M87. The fate of anyone falling into a black hole would be a painful “spaghettification,” an idea popularized by Stephen Hawking in his book “A Brief History of Time.” In spaghettification, the intense gravity of the black hole would pull you apart, separating your bones, muscles, sinews and even molecules. They are the nearest examples of about 10 million that are expected to be scattered through the Milky Way.īlack holes are tombs of matter nothing can escape them, not even light. Since then, about 50 black holes have been discovered in systems where a normal star orbits a black hole. The first black hole to be confirmed was Cygnus X-1, the brightest X-ray source in the Cygnus constellation. The properties of the normal star allow astronomers to infer the properties of its dark companion, a black hole. Since black holes are dark, they are found when they orbit a normal star. That’s so dense that protons, neutrons and electrons are no longer discrete particles. After the star’s nuclear fuel is exhausted, its core collapses to the densest state of matter imaginable, a hundred times denser than an atomic nucleus. With all we’ve learned about black holes over the past few decades, there are still many mysteries to solve.īlack holes are expected to form when a massive star dies. Galaxies where the black holes are active are called quasars. Most of the time they are inactive, but when they are active and eat stars and gas, the region close to the black hole can outshine the entire galaxy that hosts them. In particular, I’ve focused on the supermassive black holes that lurk at the center of galaxies. I’ve been studying black holes for over 30 years. And black holes are places where the laws of physics are obliterated. Also, the massive black holes seen at the center of all galaxies have insatiable appetites. If you fell into a black hole left over when a star died, you would be shredded. Andrea Ghez and Reinhard Genzel shared the other half for showing that a massive black hole sits at the center of our galaxy.īlack holes are scary for three reasons. Half of the 2020 Nobel Prize in Physics was awarded to Roger Penrose for his mathematical work showing that black holes are an inescapable consequence of Einstein’s theory of gravity. Halloween is a time to be haunted by ghosts, goblins and ghouls, but nothing in the universe is scarier than a black hole.īlack holes – regions in space where gravity is so strong that nothing can escape – are a hot topic in the news these days.
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