The first ever photo of a black hole has been revealed after years of research by an international team of scientists.
After two years of acquiring and processing data, scientists at the Event Horizon Telescope (EHT) programme presented their first results at news conferences across the world this afternoon.
Journalists gathered in Brussels, Washington, Santiago, Shanghai, Taipei, Tokyo and Lyngby in Denmark.
The results come after eight radio telescopes were pointed at two of the cosmic behemoths, one at the heart of our galaxy, the Milky Way, and another nearly 54 million light years away.
The image shows the second black hole, which lies at the centre of Messier 87 (M87), a massive galaxy in the nearby Virgo galaxy cluster.
"This is a huge day in astrophysics," US National Science Foundation director France Córdova said as the photo was revealed in Washington. "We're seeing the unseeable."
The fact that black holes do not allow light to escape makes viewing them difficult.
Scientists look for a ring of light - disrupted matter and radiation circling at tremendous speed at the edge of an event horizon - around a region of darkness representing the actual black hole.
An event horizon is the point-of-no-return precipice beyond which stars, planets, gas, dust and all forms of electromagnetic radiation get swallowed into oblivion.
The project's researchers obtained the first data in April 2017 using telescopes in Arizona and Hawaii as well as in Mexico, Chile, Spain and Antarctica.
Since then, telescopes in France and Greenland have been added to the global network, essentially creating a planet-sized observational dish.
Sheperd Doelman, from Harvard University, said: "We have seen and taken a picture of a black hole.
"This is a remarkable achievement. We now have visual evidence of a black hole. This is the strongest evidence that we have to date of the existence of black holes."
While much around a black hole falls into a death spiral and is never to be seen again, the new image captures "lucky gas and dust" circling at just far enough to be safe, co-discoverer Jessica Dempsey said.
Taken over four days when astronomers had "to have the perfect weather all across the world and literally all the stars had to align", the image helps confirm Einstein's general relativity theory, she added.
Ms Dempsey said Einstein even predicted the symmetrical shape that scientists have found.
Black holes, which come in different sizes, are formed when very massive stars collapse at the end of their life cycle.
Supermassive black holes are the largest kind, growing in mass as they devour matter and radiation and perhaps merging with other black holes.
At one of the press conferences held at the National Press Club in Washington, scientists explained that SgrA was a "complex" object and the M87 black hole had been easier to image.
They said they were hoping to release images of SgrA soon but could make "no promises".
