Looking more like the Death Star's planet-killing weapon than  tools for astronomy, the four powerful lasers of the Very Large Telescope (VLT) at the Paranal Observatory in Chile were fired for the first time into the star studded sky on April 26.

The battery of four 22 Watt lasers goes by the name, "Four Laser Guide Star Facility" (4LGSF). It's a component of the adaptive optics system of the VLT operated by the European Southern Observatory.

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The job of the four lasers that fire four gold hued laser light beams (each 30 cm in diameter) into night sky is to create "artificial stars" that aid in accurately pointing of the VLT. Most other observatories that use lasers such as the Keck Observatory in Germany are equipped with only one laser. The VLT in Chile is the first observatory operating more than one laser.

The four laser beams produce four artificial stars by illuminating sodium atoms in the atmosphere at 90 km altitude. Once they hit the sodium atoms, the lasers make the atoms glow like artificial stars that serve as a reference for the VLT's adaptive optics system. The glow is caused by the sodium atoms re-emitting the laser light.

"The artificial stars allow the adaptive optics systems to compensate for the blurring caused by the Earth's atmosphere, so that the telescope can create sharp images," said ESO in a statement.

"Using more than one laser allows the turbulence in the atmosphere to be mapped in far greater detail, to significantly improve the image quality over a larger field of view.

The 4LGSF Laser System is based on a fiber Raman laser technology developed at ESO. The VLT with its 39 meter main mirror is "the world's biggest eye on the sky." 

TagsFour Laser Guide Star Facility, very large telescope, European Southern Observatory, 22 Watt lasers