The European Southern Observatory's Very Large Telescope is shooting a freakin big laser into space, to create a virtual star to compensate for the Earth's atmospheric interference.
The resulting star appears to be in the center of the Milky Way, although it's just 56 miles up. This commonly used technique allows the VLT crew to adjust their adaptive optics system, a set of adjustable mirrors that compensate for the blurring caused by the Earth's atmosphere. Explains Space.com:
The laser is precisely tuned to energize a layer of sodium atoms found in one of the upper layers of the atmosphere. This sodium is thought to be a remnant of countless streaking meteorites. When hit by the laser's light, the sodium atoms start glowing, forming a virtual star the VLT can use as a reference.
Astronomers use this technique to obtain sharper observations. For example, when looking toward the center of our Milky Way, researchers can better monitor the galactic core, where a central supermassive black hole, surrounded by closely orbiting stars, is swallowing gas and dust.
Photo by Yuri Beletsky. [Space.com]