A Strong Earthquake Turned a High-Powered Telescope Into a Seismograph
Scientists have gotten awfully good at the business of seismography. At any moment, the Global Seismograph Network (GSM), a web of 150 instruments arrayed around the world, is reliably taking the pulse of the planet. There have been seismographs on the moon — sensitive enough to detect the footsteps of the astronauts who brought them there. A seismograph is currently at work on Mars, as part of the suite of instruments carried by NASA’s InSight lander.
Now, science has stumbled across a new — and inadvertent — kind of seismography, with earthquakes recorded not by tracings on a screen or a paper strip, but by seeming wobbles in the stars above.
On January 20, Chile was hit by a 6.7 magnitude earthquake. The country’s Atacama Desert is home to a growing array of international telescopes — thanks to its high elevation and utterly clear, dry air. At the moment the quake hit, the La Silla Observatory, just 56 miles from the epicenter of the event, was taking 10-second, long-exposure pictures of satellites in what is known as a geostationary orbit.
From the ground, geostationary satellites never appear to move because they fly at such a high altitude — more than 22,000 miles up — that their orbit matches the 24-hour rotation of the Earth. They thus seem forever to hang over a precise point on the ground, which also means that a telescope image of one them — even a long-exposure one — would read as a single point of light...
Source: TIME: Science - Category: Science Authors: Jeffrey Kluger Tags: Uncategorized atacama desert Chile Earthquake La Silla Observatory satellites space stars Source Type: news
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