Equuleus is a constellation in the northern hemisphere. Its name is Latin for "foal" or "little horse." The constellation was created by the Greek astronomer Ptolemy in the 2nd century. It is the second smallest of the 88 constellations, bigger only than Crux
In Greek mythology, Equuleus is identified with Celeris, the foal that was either the brother or offspring of Pegasus, the winged horse. Since the constellation rises before Pegasus
, it is also sometimes known as Equus Primus, or the First Horse.
Equuleus is also associated with the mythical horse struck by Poseidon's trident during a contest between him and the goddess Athena, as well as with Hippe, the daughter of the centaur Chiron who hid her pregnancy from her father. When Chiron came looking for her, she asked the gods for help and was transformed into a mare. The goddess Artemis placed her image in the sky, where she still hides from Chiron, represented by the constellation Centaurus
, with only her head visible behind Pegasus
The constellation Equuleus occupies an area of 72 square degrees and does not contain any stars with known planets. It can be seen at latitudes between +90° and -80° and is best visible at 9 p.m. during the month of September.
Equuleus does not contain any stars brighter than fourth magnitude or any notable deep sky objects. The brightest stars form the head that lies next to the head of the horse represented by the bigger and better known Pegasus constellation
The brightest star in the constellation is 
alpha Equuleus or Kitalpha ("a piece of the horse"). It is a unique spectroscopic binary star that consists of a dying G class giant and a white dwarf. The components are lying so close to each other that their spectroscopic class is mixed; G and A, both present simultaneously.
delta Equulei, the second brightest star, is also known as Pherasauval, Arabic for "the First Horse." It is a binary star approximately 60 light-years distant. 
beta Equulei is a white main sequence star with an apparent magnitude of 5.16.
Equuleus belongs to the Heavenly Waters family of constellations, along with Delphinus
, Piscis Austrinus
Constellations directly bordering Equuleus are Aquarius