Wikipedia:Today's featured article/September 25, 2015

Serpens is a constellation of the northern hemisphere, representing a serpent. One of the 48 constellations listed by the 2nd century astronomer Ptolemy, it remains one of the 88 modern constellations defined by the International Astronomical Union. It is unique among the modern constellations in being split into two non-contiguous parts, the head (Serpens Caput) to the west and the tail (Serpens Cauda) to the east. Between these two halves lies the constellation of Ophiuchus, the "Serpent-Bearer", with the body of the serpent passing behind Ophiuchus. The brightest star in Serpens is the red giant star Alpha Serpentis, with an apparent magnitude of 2.63. The Eagle Nebula and its associated cluster (pictured) are located in Serpens, as is the nearby star-forming region Westerhout 40. Extragalactic objects in Serpens include Seyfert's Sextet, one of the densest galaxy clusters known; Arp 220, the prototypical ultraluminous infrared galaxy; and Hoag's Object, the most famed of the rare ring galaxies.