New telescopes in Chile will push astronomy's boundaries

The Miami HeraldSeptember 19, 2011 

For years, the clear skies above the Atacama Desert have made northern Chile a paradise for astronomers, and the powerful telescopes here have captured some remarkable images from the distant corners of the universe.

But now, engineers are working on two massive projects that will make the current telescopes look like toys. Once finished, Chile will arguably be the best place in the world for stargazers.

“Chile really is a dream place for astronomy,” says Henri Boffin, chief astronomer at Paranal, one of the country’s most important observatories. “If you want to do modern astronomy and you want to do it in the southern hemisphere, you have to do it in Chile.”

One of the two telescopes is being built at Paranal. When it is completed in 10 years, it will be the most powerful eye on the sky anywhere in the world. The size of a football stadium, its main mirror will be 138 feet wide. That is four times bigger than the mirrors on any existing telescopes anywhere.

It is impossible to make a single curved, high-precision mirror of that size, so engineers in Europe will ship almost 1,000 small hexagonal mirrors to Chile then they’ll be fitted together like pieces in a giant jigsaw puzzle.

Simply building the new telescope will be a challenge. Paranal is 8,530 feet up in the Andes with a single access road and a forbidding climate.

The telescope will cost about $1.5 billion, weigh over 5,000 tons and will be made to withstand major earthquakes, a serious consideration in Chile. Astronomers say the images it produces will be 15 times sharper than those sent to earth by the Hubble space telescope.

The other big project in this part of Chile is ALMA which will be the world’s biggest network of radio telescopes. It consists of more than 60 giant radio dishes, assembled on the Chajnantor plateau, near the border with Bolivia and Argentina, at a dizzying altitude of 16,400 feet.

Many of the dishes are already in place, and ALMA is due to begin operations later this year.

Tim de Zeeuw, head of the European Southern Observatory (ESO), which is involved in both projects, said ALMA promises to be “as transformational for science as the Hubble space telescope.”

Much of the reason for the astronomical activity in Chile related to the desert skies, which are among the clearest in the world. Altitude is also important, particularly for ALMA. Radio telescopes pick up wavelengths from outer space, but the signals are often distorted by water vapor in the earth’s atmosphere. By building at altitude, in dry air, engineers can get above some of that moisture.

But there are other considerations, too. Being in the southern hemisphere, Chile’s observatories are not in direct competition with those in the United States and Europe, which gaze at a different part of the sky.

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