Arches Across an Arctic Sky

Explanation: What are these two giant arches across the sky? Perhaps the more familiar one, on the left, is the central band of our Milky Way Galaxy . This grand disk of stars and nebulas here appears to encircle much of the southern sky. Visible below the stellar arch is the rusty-orange planet Mars and the extended Andromeda galaxy . For a few minutes during this cold arctic night, a second giant arch appeared to the right, encircling part of the northern sky: an aurora . Auroras are much closer than stars as they are composed of glowing air high in Earth's atmosphere . Visible outside the green auroral arch is the group of stars popularly known as the Big Dipper . The featured digital composite of 18 images was captured in mid-December over the Lofoten Islands in Norway .

APOD Year in Review (2020): RJN's Night Sky Network Lecture