![]() They are also relatively small compared to the vastness of space. They are far away and shrouded by the gas and dust that clogs the center of galaxies. Supermassive black holes are extremely hard to measure. This effect, called gravitational lensing, is a core prediction of general relativity. Light from that gas is being bent by the powerful gravity of the black hole toward Earth. Some of the gas visible in the image is actually behind Sagittarius A*. The bright spots in the ring show areas of hotter gas that may one day fall into the black hole. The bright ring is the gas itself glowing. The central dark region in the image is a shadow cast by the black hole onto the gas. But black holes are surrounded by clouds of gas, and astronomers can measure this gas to infer images of the black holes within. What does the new image show?īlack holes themselves are completely dark, since nothing, not even light, can escape their gravity. ![]() Compared to most of these, Sagittarius A* is meager and unremarkable. But astronomers think there are supermassive black holes at the center of nearly all galaxies. The Milky Way’s black hole is huge compared to the black holes left behind when massive stars die. Scientists had previously been able to calculate that Sagittarius A* is 16 million miles (26 million kilometers) in diameter. The size of a black hole is defined by its event horizon – a distance from the center of the black hole within which nothing can escape. Reinhard Genzel and Andrea Ghez later shared the Nobel Prize in Physics for this discovery. Their motions suggested that at the center of the Milky Way was a black hole 4 million times the mass of the Sun. They saw stars whirling around a dark object at speeds up to a third of the speed of light. In the 1980s, two teams of astronomers started tracking the motions of stars near this mysterious source of radio waves. For decades, astronomers have been measuring blasts of radio waves from an extremely compact source there. Sagittarius A* sits at the the center of our Milky Way galaxy, in the direction of the Sagittarius constellation. Chris Impey, an astronomer at the University of Arizona, explains how the team got this image and why it is such a big deal. On May 12, 2022, astronomers on the Event Horizon Telescope team released an image of a black hole called Sagittarius A* that lies at the center of the Milky Way galaxy. Read the original article, which was published May 12, 2022. This article is republished from The Conversation under a Creative Commons license. SpaceNext50 Britannica presents SpaceNext50, From the race to the Moon to space stewardship, we explore a wide range of subjects that feed our curiosity about space!Įncyclopædia Britannica, Inc./Patrick O'Neill Riley.Learn about the major environmental problems facing our planet and what can be done about them!
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