2025年9月15日
Earth During a Powerful Solar Storm
Video Credit: NASA‘s SVS, SWRC, CCMC, SWMF; T. Bridgeman et al.
Explanation: Can our Sun become dangerous? Yes, sometimes. Every few years our Sun ejects a scary-large bubble of hot gas into the Solar System. Every hundred years or so, when the timing, location, and magnetic field connections are just right, such a Coronal Mass Ejection (CME) will hit the Earth. When this happens, the Earth not only experiences dramatic auroras, but its magnetic field gets quickly pushed back and compressed, which causes electric grids to surge. Some of these surges could be dangerous, affecting satellites and knocking out power grids — which can take months to fix. Just such a storm — called the Carrington Event — occurred in 1859 and caused telegraph wires to spark. A similar CME passed near the Earth in 2012, and the featured animated video shows a computer model of what might have happened if it had been a direct hit. In this model, the Earth’s magnetopause becomes so compressed that it went inside the orbit of geosynchronous communication satellites.
Tomorrow’s picture: stellar cathedral
强烈太阳风暴下的地球
影像提供: NASA‘s SVS, SWRC, CCMC, SWMF; T. Bridgeman et al.
说明: 太阳会变得危险吗？答案是肯定的，而且偶尔会发生。大约每隔几年，太阳就会向太阳系抛出一个庞大的高温气体泡泡。而大约每一百年左右，当时机、位置与磁场连接条件恰巧吻合时，这样的日冕物质抛射（Coronal Mass Ejection, CME）便会正面撞击地球。当这种情况发生时，地球不仅会出现壮丽的极光，其磁场也会被迅速推挤并压缩，导致电力系统产生强烈电流突波。其中一些突波可能造成严重影响，波及人造卫星，甚至瘫痪电网，而这样的损害往往需要数月才能修复。历史上最著名的一次事件便是1859年的「卡林顿事件」（Carrington Event），当时电报线路因电流过大而冒出火花。在2012年，也有一次规模相当的CME从地球附近掠过。若当时正面撞击，后果将十分惊人。这段主题影片便是电脑模拟的结果：地球的磁层顶（magnetopause）被压缩到竟然缩进了同步通讯卫星的轨道之内。
明日的图片: stellar cathedral
