New Ways to Observe the Universe

Astronomy, the most ancient of sciences, has changed beyond recognition in the past 50 years, from a communion between an astronomer and the heavens using simple equipment and telescopes, to a burgeoning, high-tech enterprise striving towards barely imaginable objectives.

To explain these changes, Broadmead residents had the privilege, on February 8, of hearing Professor Bill Blair, from Johns Hopkins University, talk on the topic "Latest technology opens new avenues in the Universe" for the Open Forum Committee. His impressive presentation was packed with information and accompanied by copious visuals.

Telescopes in space are an essential component of this high-tech enterprise. They orbit above the absorption and distortion caused by the atmosphere. A very large space telescope could, in principle, see as far as the Big Bang and the edge of the Universe. The largest telescope to date is the Hubble Space Telescope with a 2.4m diameter mirror, managed from Johns Hopkins University.

Hubble will shortly be replaced by the James Webb telescope, with a 6.5m diameter mirror, and eventually, perhaps, by the huge LUVOIR mirror, 15m in diameter. The James Webb mirror is segmented, or cutup into smaller mirrors, that must be assembled in space,with a precision measured in fractions of a wavelength of light. Segmented mirror technology can also be used on earth,and huge ground based mirrors can now be contemplated.

The largest such existing device in the US is the Keck telescope in Hawaii, with two 10m segmented mirrors. Segmented mirrors can also be used as 'adaptive optics' that can compensate for atmospheric distortions,given a 'guide star' to act as a control.These are but a few of the many areas of astronomy that are being transformed by high-tech methods.

-- Story by Richard Goody

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