The Constellation Directory


"The Dolphin"


By IAU and Sky & Telescope magazine (Roger Sinnott & Rick Fienberg) [CC-BY-3.0], via Wikimedia Commons

Abbreviation: Del
Genitive: Delphini
Constellation family: Heavenly Waters
Nearest constellations: Aquarius, Aquila, Equuleus, Pegasus, Sagitta, Vulpecula
Right ascension: 20.70h
Declination: 13.81°
Visible between latitudes: +90° and -70°
Square degrees: 189
Luminary: Rotanev (Beta Delphini)
Named stars: Rotanev, Sualocin, Deneb Dulfim
Notable deep sky objects: NGC 6891, NGC 6905, NGC 6934, NGC 7006


Delphinus by Alexander Jamieson

By Alexander Jamieson (United States Naval Observatory Library) [Public domain], via Wikimedia Commons

Delphinus is a small constellation in the Northern Hemisphere that can be seen in September.

Two of the stars in Delphinus, Rotanev and Sualocin, honor Niccolo Cacciatore, who was an assistant to an Italian astronomer named Giuseppe Piazzi who lived from 1746-1826. The Latinized version of Cacciatore's name is Nicolaus Venator, which is Sualocin Rotanev when spelled in reverse. His name was split and assigned to stars Alpha and Beta Delphini.

Delphinus lies in a part of the sky referred to the "water" section, due to the number of water-related constellations in the surrounding sky: Aquarius, Cetus, Eridanus, Pisces, and Piscis Austrinus.


In Greek mythology, Delphinus represents a dolphin who was a messenger of the sea god Poseidon. Poseidon sent out Delphinus to convince a sea nymph named Amphitrite to marry him. When the dolphin succeeded and the nymph (one of the fifty Nereids) married Poseidon, the god rewarded the dolphin with a place in the sky.