Other meanings of Canis
Constellations
Canis Minor (Latin for "lesser dog") is a small constellation in the northern celestial hemisphere, one of the 48 constellations listed by the 2nd-century astronomer Ptolemy. It is most notable for its brightest star, Procyon, the eighth-brightest star in the night sky, which forms the Winter Triangle with Sirius and Betelgeuse.
In Greek mythology, Canis Minor is often identified as one of the dogs of Orion, the hunter, with its brighter star Procyon representing the dog's body and the fainter Gomeisa its head. The constellation was catalogued by Ptolemy in the 2nd century AD, though it may have been recognized earlier by the Babylonians, who called it the "Dog of the Sun." The name Procyon derives from Greek, meaning "before the dog," because it rises shortly before Sirius, the "Dog Star" in Canis Major. In ancient Egypt, Procyon was associated with the goddess Isis and was used in temple alignments. The constellation's modern boundaries were fixed by the International Astronomical Union in 1930, and it now covers an area of 183.4 square degrees, ranking 71st among the 88 modern constellations.
Procyon (Alpha Canis Minoris) is a binary star system, consisting of a white main-sequence star and a faint white dwarf companion, Procyon B, which was first detected in 1896 by John Martin Schaeberle. Procyon lies about 11.5 light-years from Earth, making it one of the nearest bright stars. The second-brightest star, Gomeisa (Beta Canis Minoris), is a blue-white main-sequence star about 170 light-years away. The constellation contains several variable stars, such as S Canis Minoris, a Mira-type variable, and the red giant VZ Canis Minoris. It also hosts the open cluster NGC 2459, though it is sparse and often overlooked. No bright deep-sky objects lie within Canis Minor, but it is home to several faint galaxies, including PGC 26782 and PGC 26783, which are part of the Canis Minor Dwarf Galaxy, a satellite of the Milky Way discovered in 2003.
Canis Minor is best observed in the northern winter and spring, when it is high in the evening sky. It lies just north of the celestial equator, so it is visible from most of the inhabited world, except for latitudes south of about 75°S. The constellation is bordered by Gemini to the north, Cancer to the west, Hydra to the south, and Monoceros to the east. Its two brightest stars, Procyon and Gomeisa, form a distinctive pair that is easy to spot, especially because Procyon is part of the prominent Winter Triangle asterism, along with Sirius in Canis Major and Betelgeuse in Orion. For observers in urban areas, Canis Minor is a good target because its main stars are bright enough to be seen even with moderate light pollution. The best time to view it is around 9 p.m. in late February.
Beyond its classical identity, Canis Minor has several lesser-known facets. The star Procyon was used by the ancient Greeks to mark the start of the hot "dog days" of summer, though the exact timing varied by region. In Chinese astronomy, the stars of Canis Minor were part of the Vermilion Bird of the South, with Procyon known as Nan He, the "Southern River." The constellation also contains the unusual star HD 66141, which hosts a planet discovered in 2012, making it one of the few known planetary systems in the constellation. Additionally, the Canis Minor Dwarf Galaxy, discovered in 2003, is a tidally disrupted satellite of the Milky Way, and its proximity to the galactic plane makes it difficult to study. The constellation is also the namesake of the Canis Minorids, a minor meteor shower that peaks in December, though it is faint and rarely observed.
All data are based on the IAU constellation boundaries and current astronomical catalogs.
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