Budding stargazers have plenty to look at on the Web鈥攎ost major observatories have sites where you can view their images and learn about their technological tricks. For 50 years, the 5-metre Hale Telescope on Mount Palomar, California, reigned supreme as the biggest astronomical 鈥渆ye鈥� in the world. You can find it at http://astro.caltech.edu/observatories/palomar/public/index.html. Then came a revolution. In the past decade, new technologies have made possible the construction of a clutch of giant telescopes. By 2005, there could be as many as 10 telescopes with mirrors more than 8 metres across.
The biggest 鈥渓ight buckets鈥�, as astronomers call them, are the twin 10-metre Keck telescopes on top of Mauna Kea, a volcano in Hawaii. Keck I and II have 鈥渟egmented mirrors鈥�, each made of 36 hexagonal pieces. Discover more at http://www2.keck.hawaii.edu:3636/. Used together, and with smaller 鈥渙utrigger鈥� telescopes, they could one day mimic a telescope almost 100 metres across.
Other `scopes are using single 鈥渢hin-film鈥� mirrors. They include the 8-metre Subaru telescope that Japanese astronomers have built next to Keck. This has a site at http://chain.mtk.nao.ac.jp/index. Then there鈥檚 Gemini (http://hephaestus.gemini.edu/), an international project to build two 8-metre telescopes, one on Mauna Kea and another at Cerro Pach贸n in the Chilean Andes.
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And don鈥檛 forget space telescopes. High above the distorting effect of the atmosphere, they can still outperform their ground-based cousins. The daddy of them all is NASA鈥檚 2.5-metre Hubble Space Telescope at http://www.stsci.edu/pubinfo/Pictures.html. But 鈥渟on of Hubble鈥� has already been conceived. For news of the Next Generation Space Telescope, an 8-metre monster that could fly by 2007 if the US Congress gives it the green light, try http://ngst.gsfc.nasa.gov.
