Capricornus is one of the 88 modern constellations, and was also one of the 48 constellations listed by the 2nd century astronomer Ptolemy. Under its modern boundaries it is bordered by Aquila, Sagittarius, Microscopium, Piscis Austrinus and Aquarius. The constellation is in an area of sky called the Sea or Water, consisting of many water-related constellations such as Aquarius, Pisces and Eridanus.