Post-Earthquake: Why Chile's Telescopes Survived

Illustration for article titled Post-Earthquake: Why Chile's Telescopes Survived

Chile was rocked by an 8.8 magnitude earthquake on Saturday, and while hundreds were killed, has cast light on the many telescopes of Chile, built there for the low humidity and high altitudes.

Earthquake expert Anil Ananthaswamy said the telescope will have survived the quake not just because it's located 1,370km north of the earthquake's epicenter, but because of how stable the build is. Clamps can lift the 23-ton telescope's mirror when an earthquake strikes, so it swings above its setting instead.

The European Southern Observatory's VLT (pictured) was built on a 2,635 meter high mountain in the Atacama desert of Chile, which is 50 times drier than Death Valley in California. Despite the grim-sounding conditions, it survived intact:

"The primary mirror is 18 centimeters thick. Because of its weight, the mirror's precise shape can warp when it is tilted, so 150 actuators, upon which the mirror rests, continually push and pull at least once a minute to ensure that the optimal curvature is maintained. More impressive than the actuators are the clamps around the edges of the mirror, which can, at a moment's notice, lift the entire mirror, all 23 tons of it, off the actuators and secure it to the telescope's support structure in case of an earthquake (moderate quakes, of less than 7.75 Richter, are not uncommon here, thanks to the ongoing collision of the Nazca and South American plates). The entire telescope is designed to swing during an earthquake, and securing the primary mirror prevents it from rattling against the metal tubes that surround it."


Its servers went offline for a while after the quake, but have been restored—with other telescopes in the area faring just as well, with just power cuts reported so far. [Discovery News]

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Can someone please explain why, when looking at stars light-years away, a couple thousand feet of altitude will make a difference as to where telescopes are located?

I skipped physics in high school, so maybe Im missing something...