冰岛板块分界线上空的螺旋极光
影像来源与版权:Juan Carlos Casado (TWAN, StarryEarth)

说明:欣赏美景之余,也要戒慎后头的猛兽。此处的美景指头顶的螺旋状泛绿极光。这团位在美丽云朵之间的极光,旁边有明月为伴,后头则有繁星为衬托。猛兽则是这波引发极光的带电粒子,而或许某一天,这种带电粒子团会重创人类文明。1859年在出现遍及全球的极光活动之后,由太阳闪焰触发的日冕物质抛射(CME)释放出一团带电粒子,猛烈冲撞地球的磁层,造成卡林顿事件。(此事件如此强烈的部分原因)可能是先前的一次日冕物质抛射,已经在太阳与地球之间清出一条相对直接的通道。不过很可确定的是:卡林顿事件剧烈压缩了地球的磁场,在电报线上诱发强大的电流,不仅造成许多电报线放电喷出火花,也使电报操作员受到电击。如果卡林顿等级的事件发生在当今的话,可能会让全球电网和电子设备遭受空前规模的灾损。这幅主题影像是在2016年摄于冰岛的Thingvallavatn湖;此湖泊座落在地球欧亚板块与北美洲板块的分界线上,它的湖水淹没部分的断层线。(太阳闪焰=太阳耀斑;Carrington Event卡林顿事件)
翻译:“每日一天文图”成大物理分站

Spiral Aurora over Icelandic Divide
Image Credit & Copyright: Juan Carlos Casado (TWAN, StarryEarth)

Explanation: Admire the beauty but fear the beast. The beauty is the aurora overhead, here taking the form of great green spiral, seen between picturesque clouds with the bright Moon to the side and stars in the background. The beast is the wave of charged particles that creates the aurora but might, one day, impair civilization. In 1859, following notable auroras seen all across the globe, a pulse of charged particles from a coronal mass ejection (CME) associated with a solar flare impacted Earth’s magnetosphere so forcefully that they created the Carrington Event. A relatively direct path between the Sun and the Earth might have been cleared by a preceding CME. What is sure is that the Carrington Event compressed the Earth’s magnetic field so violently that currents were created in telegraph wires so great that many wires sparked and gave telegraph operators shocks. Were a Carrington-class event to impact the Earth today, speculation holds that damage might occur to global power grids and electronics on a scale never yet experienced. The featured aurora was imaged in 2016 over Thingvallavatn Lake in Iceland, a lake that partly fills a fault that divides Earth’s large Eurasian and North American tectonic plates.
Astronomy Picture of the Day 04/21/2019