2020 June 23
Explanation: What if you could see X-rays? The night sky would seem a strange and unfamiliar place. X-rays are about 1,000 times more energetic than visible light photons and are produced by violent explosions and high temperature astronomical environments. Instead of the familiar steady stars, the sky would seem to be filled with exotic stars, active galaxies, and hot supernova remnants. The featured X-ray image captures in unprecedented detail the entire sky in X-rays as seen by the eROSITA telescope onboard Spektr-RG satellite, orbiting around the L2 point of the Sun-Earth system, launched last year. The image shows the plane of our Milky Way galaxy across the center, a diffuse and pervasive X-ray background, the hot interstellar bubble known as the North Polar Spur, sizzling supernova remnants such as Vela, the Cygnus Loop and Cas A, energetic binary stars including Cyg X-1 and Cyg X-2, the LMC galaxy, and the Coma, Virgo, and Fornax clusters of galaxies. This first sky scan by eROSITA located over one million X-ray sources, some of which are not understood and will surely be topics for future research.
Tomorrow’s picture: inverted cloud city
说明：如果你拥有X射线视力，你会看到既奇特又陌生的夜空。能量大约是可见光1,000倍以上的X射线，产生于剧烈的爆炸事件和高温的天文环境。因此，在X射线天空中不会有我们很熟悉的正常恒星，而是满布着奇特的恒星、活跃星系和炽热的超新星遗迹。这幅清晰度空前的X射线全天图，是由去年发射的Spektr-RG卫星上的eROSITA巡天望远镜所拍摄。这幅影像呈现了横过中心的银河系中央盘面、弥漫无所不在的X射线背景辐射、名为北银极支的炽热星际气泡、极热的超新星遗迹（诸如：Vela、Cyg X-1、X-2及Cas A）、大麦哲伦星系、以及后发、室女和天炉星系团。eROSITA的首次巡天观测，找到了1百多万个X射线源，其中有一些起源不明，而它们必然会成为未来研究的主题。
明日的圖片：inverted cloud city