Astronomy Picture of the Day——日落时分的切伦科夫望远镜
Discover the cosmos! Each day a differentimage or photograph of our fascinating universe is featured, along with a briefexplanation written by a professional astronomer.
Cherenkov Telescope at Sunset
Image Credit & Copyright: Sarah Brands(University of Amsterdam)
Explanation: On October 10, a new telescopereflected the light of the setting Sun. With dark horizon above and sunsetcolors below, its segmented mirror inverts an image of the beautiful eveningsky in this snapshot from the Roque del Los Muchachos Observatory on the CanaryIsland of La Palma. The mirror segments cover a 23 meter diameter and aremounted in the open structure of the Large Scale Telescope 1, inaugurated asthe first component of the Cherenkov Telescope Array (CTA). Most ground-basedtelescopes are hindered by the atmosphere that blurs, scatters, and absorbslight. But cherenkov telescopes are designed to detect very high energy gammarays and actually require the atmosphere to operate. As the gamma rays impactthe upper atmosphere they produce air showers of high-energy particles. Alarge, fast camera at the common focus images the brief flashes of opticallight, called Cherenkov light, created by the air shower particles. The flashesreveal the incoming gamma ray timing, direction, and energy. Ultimately morethan 100 Cherenkov telescopes are planned for the CTA at locations in bothnorthern and southern hemispheres on planet Earth.
日落时分的切伦科夫望远镜
解释：去年10月，一架全新望远镜反射日落的光芒。在拉帕尔玛的加那利群岛上的洛克德洛斯穆察克斯天文台拍摄的这幅照片中，黑色的地平线在上方，彩色落日在下方，它的拼接镜反转美丽夜空的影像。这些拼接镜的总直径可达23米，安装在大尺度望远镜的开放式结构中，成为切伦科夫望远镜阵列的第一部分。大部分的地面望远镜受大气层阻碍（大气层的模糊、散射和吸光）。但切伦科夫望远镜不同，它是被设计用来探测非常高能的伽玛射线的，实际上反而需要大气层合作。当伽马射线撞击上层大气，会产生高能粒子大气簇射。大型高速相机拍摄可见光的短暂闪光，被称为切伦科夫光，是大气簇射粒子产生的。这些闪光揭示入射伽马射线计时、方向和能量。目前计划在地球南北半球总共建设100多架切伦科夫望远镜。
近期文章：
Astronomy Picture of the Day——相机镜头下的猎户座