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.
Explanation: What are these gigantic blue arcs near the Andromeda Galaxy (M31)? Discovered in 2022 by amateur astronomers, the faint arcs -- dubbed SDSO 1 -- span nearly the same angular size as M31 itself. At first, their origin was a mystery: are they actually near the Andromeda Galaxy, or alternatively near to our Sun? Now, over 550 hours of combined exposure and a collaboration between amateur and professional astronomers has revealed strong evidence for their true nature: SDSO 1 is not intergalactic, but a new class of planetary nebula within our galaxy. Dubbed a Ghost Planetary Nebula (GPN), SDSO 1 is the first recognized member of a new subclass of faded planetary nebulas, along with seven others also recently identified. Shown in blue are extremely faint oxygen emission from the shock waves, while the surrounding red is a hydrogen-emitting trail that indicates the GPN's age.
Authors & editors:
Robert Nemiroff
(MTU) &
Jerry Bonnell (UMCP)
NASA Official: Amber Straughn
Specific rights apply.
NASA Web Privacy,
Accessibility,
Notices;
A service of:
ASD at
NASA /
GSFC,
NASA Science Activation
& Michigan Tech. U.