Astronomy Picture of the Day—射向银心的激光

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 March 7

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 slightly deformedto minimize this blurring. In this case, a VLT was observing our Galaxy'scenter, and so Earth's atmospheric blurring in that direction was needed. Asfor inter-galaxy warfare, when viewed from our Galaxy's center, no casualtiesare expected. In fact, the light from this powerful laser would combine withlight from our Sun to together appear only as bright as a faint and distantstar.

射向银心的激光

解释：是谁在向银心射出一束强大的激光？这当然不是进入银河系大战的第一步，而是智利甚大望远镜（VLT）的天文学家正在试图测量地球不断变化的大气层扭曲。受到激光激发的高层大气原子的恒定成像，看上去就像一颗人造星星，这让天文学家能够即时测量大气模糊的信息。这个信息被反馈给甚大望远镜的镜片，然后，镜面略微变形，使得这种模糊最小化。在这张图中，甚大望远镜正在观测银心，因此需要此方向上的地球大气模糊信息。