A black hole on our doorstep

[pappagooch]

The Atacama Desert in northern Chile is one of the most inhospitable places on Earth. It's 2,600 meters above sea level and receives almost no rainfall. Visitors, when they are not tending to dry skin and nosebleeds caused by the altitude, often compare the terrain to the barren red rocks that cover the surface of Mars.

The comparison is more than just subjective. Last week the journal Science published a paper comparing the soil in Atacama with that examined by the Viking landers sent to Mars in the 1970s. Using technology unavailable to the Viking landers, scientists have isolated organic compounds from the Atacama soil. The hope is that the soils will help researchers design better experiments for detecting life in Martian soil.

Almost lifeless though the desert is, however, a different group of scientists has another good reason to go there: the four giant white cylinders of the Paranal Observatory. These form the European Southern Observatory's imaginatively named Very Large Telescope.

Each of the four telescopes has a mirror 8.2 meters in diameter, making each, individually, among the largest telescopes in the world. Yet they can also combine their light to achieve the sensitivity of a single 16-meter telescope and the resolution of a single 200-meter telescope. Working together, the four telescopes of the VLT can see the universe in unprecedented detail.

"Using the VLT, we have seen the highest red shift yet observed," said Reinhard Genzel of the Max Planck Institute for Extraterrestrial Physics in Garching, Germany, in a telephone interview. Red shift occurs when the object being observed is moving away from the observer. Since the universe is expanding, all the objects we see in the sky are moving away from us. The further away a stellar body is, the higher the red shift of the light we see from it.

"We have now detected massive black holes formed only 800 million years after the Big Bang," enthused Genzel. "We are now 14 billion years after the Big Bang, so we are looking at objects only 5 or 7 percent of the age of the universe. It's really amazing."

But Genzel was in the news last month for his work with an international team of astronomers on an object much closer to home. At the center of our own galaxy, the Milky Way, sits a ravenous monster: a supermassive black hole.

British science writer Nigel Calder has compared the black hole to a beast from Greek mythology. In a maze on Crete there once lived a Minotaur, Calder said, and the Minotaur demanded a diet of young people. "Now the maze is a galaxy, and at the core of that vast congregation of stars lurks a black hole that feeds on gas or dismembered stars."

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