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Friday, September 18, 1998 Published at 15:30 GMT 16:30 UK


Sci/Tech

Peering into a black hole

A glimpse into the heart of a quasar

Astronomers are using a telescope larger than the Earth to examine objects 6.3 billion light years away.

Our science editor Dr David Whitehouse takes up the story.

In astronomy big is best. The larger a telescope is the more detail it can see in space. This is why the mirrors of optical telescopes get ever larger or are made of more and more add-on segments.

It is the same with radio telescopes. The largest such telescope is the huge bowl cut into the ground in Puerto Rico, 300 metres (1,000ft) in size.

Now astronomers have gone one better. They have linked 40 radio telescopes on the ground with one in space. Essentially they have made a telescope bigger than the Earth.

Linking telescopes together this way is not new. Since the 1950s astronomers have been linking radio telescopes culminating in a telescope the size of the Earth. But now they have left our planet.


[ image: Halca before launch]
Halca before launch
In the early 1980s scientists used a Nasa satellite to try to make a superlarge telescope, but the observations were difficult.

Now they have used a Japanese radio telescope called Halca launched into orbit last year.

With Halca they have the power of a telescope equivalent to the distance between Halca and the Earth, up to 30,000km.

This translates into seeing very fine detail in space.

Like the object designated QSO 1156+295. It is a quasar, believed to be a supermassive black hole swallowing vast amounts of gas and dust and ejecting into space, with almost unimaginable violence, jets of superhot gas.

The new image of QSO 1156+295 looks right into its central regions, to within a few light years of the black hole itself.

QSO 1156+259 is 6.3 billion light years from Earth yet astronomers can make out detail as small as the distance between the Earth and the nearest stars to us.

Such images will help astronomers work out what is going on around these black holes that are half a universe away.

The research is published in the journal 'Science'.



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