New Delhi:
Astronomers on Wednesday have finally revealed the first photo of a black hole which is almost 500 million trillion kilometres away. It has been photographed by a network of eight telescopes across the world.
Using data from six telescopes located across the world, the scientists involved in the Event Horizon Telescope (EHT) project have imaged the Sagittarius A* -- the blackhole located at the centre of the Milky Way galaxy -- and another massive black hole 53.5 million light-years away in galaxy M87. The results were announced at 6.30 pm IST on Wednesday.The gravitational pull of black holes lets nothing -- not even particles and electromagnetic radiation such as light -- escape from inside it.
This makes imaging a blackhole nearly impossible. Blackholes swallow the surrounding gas, which swirls around in a flattened disk, spiralling into it at speeds close to light. The radiation from this hot whirlpool, however, can be seen.
Scientists have imaged this radiation, expecting to see the shadow of the blackhole against it.
Sagittarius A* has a mass approximately four million times that of the Sun, but it only looks like a tiny dot from Earth, 26 000 light-years away.
To image such a large space object, scientists used a Nobel Prize winning concept called 'Aperture Synthesis', described by British astronomer Martin Ryle where data from many small telescopes placed far apart is combined.
The technique, which has been used to make radio images for many decades, provides results similar to using a single telescope as big as the area over which the smaller ones are located.
The ETH project used eight telescopes spread over different locations in the US, Chile, Spain, Mexico, Antarctica, Mexico, Denmark and France to create a result similar to having used an Earth-sized telescope.
