November 17, 2020
If the universe seems cold from a distance, birthdays are part of its rebuttal.
A Glowing STEVE and the Milky Way
Birthday · November 17, 2020
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APOD published November 17, 2020. Full image credits are on the original APOD entry below. A publication-date match, not a photo taken on your date. Independent of NASA.
What's creating these long glowing streaks in the sky? No one is sure. Known as Strong Thermal Emission Velocity Enhancements (STEVEs), these luminous light-purple sky ribbons may resemble regular auroras, but recent research reveals significant differences. A STEVE's great length and unusual colors, when measured precisely, indicate that it may be related to a subauroral ion drift (SAID), a supersonic river of hot atmospheric ions thought previously to be invisible. Some STEVEs are now also thought to be accompanied by green picket fence structures, a series of sky slats that can appear outside of the main auroral oval that does not involve much glowing nitrogen. The featured wide-angle composite image shows a STEVE in a dark sky above Childs Lake, Manitoba, Canada in 2017, crossing in front of the central band of our Milky Way Galaxy.