Articles - 'a', 'an' and 'the'

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Astronomers have taken first ever photograph of black hole. It is located in far, distant galaxy called M87, which is 500 million trillion km from Earth. That gargantuan number is five followed by twenty zeroes. Scientists estimate black hole to have diameter of 40 billion km and to be three million times larger than our planet. Lead astronomer Professor Heino Falcke spoke to BBC about the black hole. He said: "What we see is larger than the size of our entire Solar System. It has mass 6.5 billion times that of the Sun. And it is one of heaviest black holes that we think exists. It is absolute monster - the heavyweight champion of black holes in the Universe."

The image of black hole was captured by array of eight linked telescopes called Event Horizon Telescope (EHT). No single telescope exists that is powerful enough to capture image. Each of the EHT telescopes is located high up on volcanoes in Hawaii and Mexico, mountains in the USA and Spain, desert in Chile, and in Antarctica. A team of 200 scientists pointed networked telescopes towards the M87 galaxy and scanned it over period of 10 days. The data they gathered was stored on hundreds of hard drives. It was then collated and processed to produce image that is now landmark in space exploration. Professor Sheperd Doeleman called it " extraordinary scientific feat".

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