Astronomy Picture of the Day

Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

2023 December 27
A waterfall is shown in the image center below a starry
sky. Arching above the waterfall is a colorful aurora. Arching
above the aurora is the central band of the Milky Way. 
Please see the explanation for more detailed information.

Rainbow Aurora over Icelandic Waterfall
Image Credit & Copyright: Stefano Pellegrini

Explanation: Yes, but can your aurora do this? First, yes, auroras can look like rainbows even though they are completely different phenomena. Auroras are caused by Sun-created particles being channeled into Earth's atmosphere by Earth's magnetic field, and create colors by exciting atoms at different heights. Conversely, rainbows are created by sunlight backscattering off falling raindrops, and different colors are refracted by slightly different angles. Unfortunately, auroras can’t create waterfalls, but if you plan well and are lucky enough, you can photograph them together. The featured picture is composed of several images taken on the same night last November near the Skógafoss waterfall in Iceland. The planning centered on capturing the central band of our Milky Way galaxy over the picturesque cascade. By luck, a spectacular aurora soon appeared just below the curving arch of the Milky Way. Far in the background, the Pleiades star cluster and the Andromeda galaxy can be found.

Your Sky Surprise: What picture did APOD feature on your birthday? (post 1995)
Tomorrow's picture: open space

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