First image of a black hole

Astronomers have captured the first ever image of a black hole, showing a dark shadow surrounded by a glowing ring of light.

The picture was released on 10 April by the Event Horizon Telescope collaboration, a network of radio telescopes around the world, at simultaneous press conferences in several countries.

The image

The black hole is at the centre of a galaxy called Messier 87, about 55 million light years from Earth. It has a mass around 6.5 billion times that of the Sun.

A black hole's gravity is so strong that nothing, not even light, can escape it. What the image shows is the shadow of the black hole against the hot gas swirling around it, which glows as it is heated to billions of degrees.

The picture closely matches what was predicted by Einstein's general theory of relativity.

A telescope the size of the Earth

No single telescope is powerful enough to see such a small object at such a distance. Instead, eight radio telescopes in places including Hawaii, Chile, Spain and Antarctica were linked together to act as one giant telescope the size of the Earth.

The observations were made over several days in April 2017. The telescopes collected so much data that it had to be flown on hard drives to computing centres, rather than sent over the internet.

It then took two years to process and check the data.

A global effort

More than 200 scientists from around the world worked on the project. British researchers were involved, and the James Clerk Maxwell Telescope in Hawaii, which the UK helped to build, was one of the telescopes used.

Why it matters

Scientists have had strong evidence for black holes for decades, from their effects on nearby stars and gas, but this is the first time one has been seen directly.

The image will allow scientists to test their theories about how black holes behave and how they power some of the most energetic objects in the universe.

The team hopes to produce an image of Sagittarius A*, the black hole at the centre of our own galaxy, the Milky Way.

The image has been shared around the world, and scientists say it is a landmark in the history of astronomy.