流星解体时的元素发光

流星解体时的元素发光

ByNASA中文

2023年7月24日 Chemicals Glow as a Meteor Disintegrates Image Credit & Copyright: Michael Kleinburger Explanation: Meteors can be colorful. While the human eye usually cannot discern many colors, cameras often can. Pictured here is a fireball, a disintegrating meteor that was not only one of the brightest the photographer has ever seen, but colorful. The meteor was captured by chance in mid-July with a camera set up on Hochkar Mountain in Austria to photograph the central band of our Milky Way galaxy. The radiant grit, likely cast off by a comet or asteroid long ago, had the misfortune to enter Earth’s atmosphere. Colors in meteors usually originate from ionized chemical elements released as the meteor disintegrates, with blue-green typically originating from magnesium, calcium radiating violet, and…

云层上方的极光

云层上方的极光

ByNASA中文

2021年05月30日 Aurora over Clouds Image Credit & Copyright: Daniele Boffelli Explanation: Auroras usually occur high above the clouds. The auroral glow is created when fast-moving particles ejected from the Sun impact the Earth’s magnetosphere, from which charged particles spiral along the Earth’s magnetic field to strike atoms and molecules high in the Earth’s atmosphere. An oxygen atom, for example, will glow in the green light commonly emitted by an aurora after being energized by such a collision. The lowest part of an aurora will typically occur about 100 kilometers up, while most clouds exist only below about 10 kilometers. The relative heights of clouds and auroras are shown clearly in the featured picture in 2015 from Dyrholaey, Iceland. There, a determined astrophotographer withstood high winds…