Ursa Major III/UNIONS 1 (UMa3/U1 for short) is the least luminous and lowest-mass Milky Way satellite ever discovered, and possibly one of the most dark matter-dominated systems known. Hidden in this deep sky image (left) is Uma3/U1, a miniscule group of stars (right) bound together by their own gravity in orbit around the Milky Way Galaxy. Image credit: CFHT / S. Gwyn / S. Smith. UMa3/U1 has a mass of only 16 solar masses and consists of only five...