02-06-2007 The Telescope: a brief history (Article 88)

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Simon Kenny
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Location: Shannon, Co. Clare, Ireland

02-06-2007 The Telescope: a brief history (Article 88)

Post by Simon Kenny » Wed Feb 04, 2009 11:00 am

The Telescope: a brief history (Article 88)

The logo above this article has the usual picture of astronomers: looking through a telescope on cold winter nights, busily searching for stars, comets, and more exotic objects in the celestial zoo! For most amateur astronomers, this is still true.
If you are new to astronomy and you love looking at the night sky, few things in life are more thrilling or rewarding than watching a close-up view of Jupiter and its moons or Saturn and its rings. Yes, we’ve seen excellent photos of these many times, but it doesn’t equal the thrill of seeing their pale, wispy orbs come into focus in a telescope. The experience is enhanced by knowing that other famous amateurs felt the same way when they searched the skies with more primitive instruments and discovered some of its mysteries.
Galileo was the first to use a telescope this way and was amazed by the views of the Moon and Jupiter with its four great moons (the Galilean Moons) through his small instrument. What he saw led him to understand for the first time the true nature of the Solar System, with the Sun at its centre. Giovanni Cassini, another Italian astronomer, was drawn by the glow of Jupiter and Saturn in his eyepiece. He discovered Jupiter’s great Red Spot, a massive hurricane that still rages around the planet. He also discovered that Saturn’s rings had a significant gap: the Cassini Division, currently under study, appropriately, by NASA’s Cassini Spacecraft! Lord Rosse of Birr, Co. Offaly must have felt that same thrill, when he focused his massive self-built telescope on a pale, wispy, circular cloud, which he called the Whirlpool Nebula. What he had really observed was a galaxy of stars like our Milky Way, now known as the Whirlpool Galaxy, and is located below the handle of ‘The Plough’.

However, cutting-edge astronomy is no longer done this way. Smaller telescopes have been superseded by ever larger units. Lord Rosse’s huge 72-inch ‘Leviathan’ was eventually dwarfed by a flotilla of larger telescopes scanning the cosmic ocean on voyages of discovery. The latest telescopes are so massive they test the limits of modern technology. Several have mirrors over eight metres across. The biggest of these, for now, are the Keck Telescopes in Hawaii, with whopping 10 metre diameter segmented mirrors.

And still the professional astronomers want more! In cutting-edge astronomy, the objects under study are very faint and very remote. Their presence is betrayed only by the faintest glimmer of light that passed through the vastness of space over aeons of time. Like the Whirlpool Nebula in the 1840s, many may hold the key to the next major discovery. So making bigger telescopes to pick up those few photons of light is deemed well worth the effort.

The thrill of guessing what’s just around the corner and the delight of discovery can still be experienced by all astronomers. If you join us, prepare to be bitten by the bug!
Our June meeting is on Wed. 6th at 8:00pm in room 206 in Mary Immaculate College and Dr. Emma Watson of the Dublin Institute for advanced Studies will give a talk on ‘The birth of stars and planets’. Clear skies!

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