July 21st, 2015
bservatories don’t just gaze into the endless starry abyss above our heads; sometimes that’s not enough. Sometimes they shoot righteous 40-watt lasers into the great beyond too. Obviously it looks awesome, and this stellar timelapse showcases exactly how awesome. (Spoilers: very awesome.)
The location is the Mauna Kea Observatories in Hawaii, and this new, fantastic footage was shot by Sean Goebel, an astronomy grad student at the University of Hawaii. You’d be forgiven for thinking that while the beautiful starscape is real, that the lasers are some sort of after-effect to add a little sci-fi flair. They aren’t though. And while the timelapse is new, the lasers have been around for a while. Goebel explains on his website:
Actually, the lasers are real. They’re used for adaptive optics. Just as waves of heat coming off pavement blur out the detail in faraway objects, winds in the atmosphere blur out fine detail in the stars/galaxies/whatever is being observed. This is the reason that stars twinkle. The laser is used to track this atmospheric turbulence, and one of the mirrors in the telescope bends hundreds of times per second in order to cancel out the blurring. Adaptive optics is pretty cool, and was the topic of my first 8-month research project in graduate school.
A typical laser pointer that you might use to point at stuff/exercise your cat is about 5 mW. That’s five one-thousandths of a watt. Not a whole lot of power. And yet it’s enough to blind airplane pilots. The lasers on the telescopes are in the range of 15-40 watts. The FAA calls a no-fly zone over the area when a laser is in use, and two people have to stand around outside in the freezing temperatures and watch for airplanes. Each of them has a kill switch to turn off the laser in case an airplane comes near. Additionally, the telescope has to send its target list to Space Command ahead of time. Space Command then tells them not to use the laser at specific times, ostensibly to avoid blinding spy satellites. However, you could calculate the spy satellite orbits if you knew where they were at specific times, so Space Command also tells the telescope to not use the laser at random times when no satellites are overhead.
Just when you thought laser cannons couldn’t get any cooler.
Also: That soundtrack is “All Is Violent, All Is Bright” by God Is An Astronaut, and you should check out the whole album because it is so rad.
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