Skip to main content

NASA Astronomy Picture of the Day:

What is that unusual red halo surrounding this aurora? It is a Stable Auroral Red (SAR) arc. SAR arcs are rare and have only been acknowledged and studied since 1954. The featured wide-angle photograph, capturing nearly an entire SAR arc surrounding more common green and red aurora, was taken earlier this month from Poolburn, New Zealand, during an especially energetic geomagnetic storm. Why SAR arcs form remains a topic of research, but is likely related to Earth's protective magnetic field, a field created by molten iron flowing deep inside the Earth. This magnetic field usually redirects incoming charged particles from the Sun's wind toward the Earth's poles. However, it also traps a ring of ions closer to the equator, where they can gain energy from the magnetosphere during high solar activity. The energetic electrons in this ion ring can collide with and excite oxygen higher in Earth's ionosphere than typical auroras, causing the oxygen to glow red. Ongoing research has uncovered evidence that a red SAR arc can even transform into a purple and green STEVE.

Photo by Tristian McDonald; Text: Tiffany Lewis (Michigan Tech U.)

A Repost

Posted by MFish Profile 01/03/24 at 05:11AM Share Poetry See more by MFish

Sometimes, reposting helps me with
this process of living. This is from December 23, 2017

A Comment by Loy

Your avatar
Loy • 01/03/2024 at 11:38PM • Like 1 Profile

Very touching and sweet poem.

The removal of the Great Works Dam on the Penobscot River in Old Town, Maine shows that when dams are removed, a river and its fish can recover with surprising speed. More at Reasons to be Cheerful ➜

NASA Astronomy Picture of the Day:

Can a rocket make the Moon ripple? No, but it can make a background moon appear wavy. The rocket, in this case, was a SpaceX Falcon Heavy that blasted off from NASA's Kennedy Space Center last week. In the featured launch picture, the rocket's exhaust plume glows beyond its projection onto the distant, rising, and nearly full moon. Oddly, the Moon's lower edge shows unusual drip-like ripples. The Moon itself, far in the distance, was really unchanged. The physical cause of these apparent ripples was pockets of relatively hot or rarefied air deflecting moonlight less strongly than pockets of relatively cool or compressed air: refraction. Although the shot was planned, the timing of the launch had to be just right for the rocket to be transiting the Moon during this single exposure.

Photo by Steven Madow

QUICK LINKS

Share some of your memories and history of Camano Island

Hunger impacts all of us | 360-435-1631

360-454-6973 - Camano Island, WA

Snohomish, Skagit and Island County

100% Satisfaction - 360-572-4737

SECURITY & SURVEILLANCE SYSTEMS - HOME AUDIO  425-379-7733