AstronomyPicture of the Day—20190108

Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

2019 January 8

ALaser Strike at the Galactic Center

ImageCredit: Yuri Beletsky (Carnegie Las Campanas Observatory, TWAN), ESO

Explanation:Why are these people shooting a powerful laser into the center of our Galaxy?Fortunately, this is not meant to be the first step in a Galactic war. Rather,astronomers at the Very Large Telescope (VLT) site in Chile are trying tomeasure the distortions of Earth's ever changing atmosphere. Constant imagingof high-altitude atoms excited by the laser -- which appear like an artificialstar -- allow astronomers to instantly measure atmospheric blurring. Thisinformation is fed back to a VLT telescope mirror which is then slightlydeformed to minimize this blurring. In this case, a VLT was observing ourGalaxy's center, and so Earth's atmospheric blurring in that direction wasneeded. As for inter-galaxy warfare, when viewed from our Galaxy's center, nocasualties are expected. In fact, the light from this powerful laser wouldcombine with light from our Sun to together appear only as bright as a faintand distant star.