APOD: 2025 August 4 Б Blue Arcs Toward Andromeda
4.08.2025 | Астрономическая картинка дня

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?