The Southern Pinwheel Galaxy (M83) in Hydra checks almost every box an amateur astronomer could desire. This stunning barred spiral spans a hefty 14′ and, at magnitude 7.5, ranks among the sky’s 10 brightest galaxies. Its only drawback is location — at a declination of –30°, it lies farther south than any other galaxy in Messier’s catalog. M83 stands out for its striking spiral arms, which feature an abundance of glittering blue star clusters and the pinkish emission nebulae that give birth to them. Astronomers think the galaxy’s high rate of star formation stems from an encounter with another galaxy. Some researchers suspect the nearby dwarf irregular NGC 5253 is the cause, while others point to a possible second nucleus in M83’s core as the remnant of the offending galaxy