The first idea of a large body so massive that even light cannot escape was produced in 1784 by John Michell. He had concluded that the mass would have to have the same density as the Sun and it could be influenced enough by gravity to shoot massive light rays from the surface of the star. This definitely sparked interests by the proposal that giant, essentially invisible stars seemed to be hiding in space, however modern studies have shown to discredit Michell. Recently scientist have been able to capture the first ever image of a black hole.
So what exactly is a black hole? A black hole is a region of spacetime exhibiting very strong gravitational effects that nothing can escape from the inside, not even light. The general relativity theory, first developed by Einstein in 1915, predicts that highly compacted masses can deform spacetime to form a black hole. The black hole is almost impossible to observe because the temperature is in the billionths of a kelvin. The black holes of stellar mass form when a massive star collapses towards the end of its lifecycle. Once a black hole has been created, it will grow by absorbing its surroundings. It is still unpredictable how much a black hole can consume.
Black holes only existed in theory made by scientist, but on April 10th of 2019 astronomers at the Harvard-Smithsonian were able to capture the first image. The director of this operation, Shep Doeleman, stated in a press conference in Washington, D.C that “we have seen what we thought was unseeable.” The imaged resembled a smoke ring and is said to be 55 million light-years away from Earth. It exists in a galaxy known as Messier 87, which lays in the constellation Virgo.
The announcement of the black hole image was first brought to Washington, D.C along with five other locations around the world. Credit is given to 200 members through an international collaboration which involved nine telescopes. Many of the astrophysicists thought Einstein would be proud to see that his theory of conditions of extreme gravity have held up to today’s society. The image was emerged from two long years of computer analysis of observations from a network of radio antennas. These radio antennas are called the Event Horizon Telescope and had observed the galaxy in Virgo for 10 days in April of 2017.
Not only did scientist discover a black hole in the galaxy of Virgo, but also at the heart of the Milky Way. 26,000 light-years away from Earth lays another black hole with an approximate mass of 4.1 million stars which we call Sagittarius A. Most black holes are the gravitational dead stars that have burned up all of their fuel and have collapsed. However, some are hidden in the center of a galaxy and can be millions or billions of times more massive than our sun.
People have begun to question why haven’t scientist ever captured an image of a black hole before. Although black holes are massive, they are still small in space. Comparably speaking, taking a picture of a black hole would be like trying to capture an image of a compact disc laying on the moon’s surface. Not only are they hard to find, but black holes are surrounded by material that deflects the light that surrounds the black hole. Before the image of the black hole was captured, scientist had to only rely on observed behaviors from surrounding objects. Since black holes consume stars, the temperature of the star being consumed heats up and they emit X-ray signals that can be detectable by telescopes. Not only does the temperature act as a signal, but black holes can also spit out charged particles in large sums. This is also detectable by scientist’s instruments.
Thanks to Einstein’s theory of general relativity, scientist can confirm everything that they have learned about black holes. As scientist push towards to future, and with technology advancing, scientist will be able to capture more images of black holes. Not only that, but they will be able to track and study black holes more.