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Hey diddle diddle,
The cat and the fiddle,
The cow jumped over the moon.
The little dog laughed to see such fun
And the dish ran away with the spoon.
–  English nursery rhyme, 1765

The Constellation Canis Minor

Canis Minor, 'the small dog', is one of the original 48 constellations mentioned by Ptolemy in antiquity. Arabian astronomers knew this star group as Al Kalb al Asghar, which means 'lesser dog'.

By the 19th Century, every astronomer worth their salt had attempted to get a constellation named after their favourite thing, and there were over 100 in existence. In 1922, the International Astronomical Union (IAU) eliminated all but the now officially recognised 88. It decided to keep the 'little dog' by virtue of its famous star, Procyon. In 1930, the IAU formed official 'borders' between each constellation; fittingly Canis Minor is one of the smallest, ranking 71st in the list. It shares borders with Gemini, Monoceros, Hydra and Cancer. A small portion of Canis Minor overlaps an arm of our galaxy, the Milky Way. However, there are no Messier objects, nor even anything on the NGC or IC² to report. The deep-sky enthusiast would be better off ignoring this little pup and swinging their optical aid into neighbouring Monoceros.

Mythology

Greek story-teller Hyginus taught us that Canis Minor represents Maera, the dog of Icarius, who learned how to make wine out of grapes from Dionysus³, the god of wine.

Icarius gave his wine to some shepherds. When they became intoxicated they thought he had done them harm, so beat him up. As he lay dying, his faithful dog, Maera, scampered for help, reaching Icarius' daughter, Erigone, whom he led back to his master's now dead body. Distraught Erigone committed suicide. Maera remained with their bodies until he too died. King of the gods Zeus was so touched by the drama that he honoured Maera by turning him into the stars which form the constellation Canis Minor.

In an alternative myth, Canis Minor is the smaller of Orion's two hunting dogs, which should not be confused with Canes Venatici, the stellar representation of the two hounds Chara and Asterion straining at the leash held by Boötes (the Herdsman).

Stars

Some stars have proper names. For example, Procyon is the common name for alpha Canis Minoris. The scientific star names are formed from a letter of the Greek alphabet, and combined with the genitive of the constellation name to make the 'Bayer designation'. Other, unnamed stars are known by their catalogue number, including newly discovered variable stars like YZ Canis Minoris.

Procyon

The 1st-magnitude yellow-white main sequence subgiant star Procyon is the eighth-brightest in the night sky. In Greek, Procyon means 'before the dog' (because Procyon rises just prior to Sirius, alpha Canis Majoris, aka the 'Dog Star'). It is so well known it has several names from different cultures, including Algomeysa, Antecanis and Elgomaisa.

Procyon has seven times the luminosity of our Sun, and is one of the largest stars within 20 light years⁴ of us. From our vantage point, Procyon gleams a rich cream colour, shining so brightly because it lies at the relatively close distance of 11.4 light years.

Procyon forms an apex of the Winter Triangle  asterism with Betelgeuse (alpha Orionis) and Sirius. Procyon has entered the final process of its evolution by converting its remaining hydrogen into helium. When all the hydrogen is used up, it will shrink to a white dwarf star, because it does not have enough mass to become a supernova.

Procyon B

Alpha² Canis Minoris (Procyon B) is a white dwarf companion to Procyon. It was detected by Arthur von Auwers in 1862. Although it could not be seen, its presence was suspected due to the optical irregularities of the main component. It was first recorded visually by John M Schaeberle in 1896. Procyon B lies around 15 AU (astronomical units) from its interstellar companion.

Other Stars

Beta Canis Minoris, Gomeisa, is the only other named star of this constellation. Gomeisa means 'the bleary-eyed one' - an analogy with the Greek legend about the discovery of wine fermentation from grapes, perhaps. Other variations of the name include Gomelza and Algomeyla.

Gamma is an orange giant with a smaller, unresolved companion. This means we know there is another gravitationally bound body due to the erratic behaviour of gamma, but the partner has not been detected for classification.

Delta is a multiple star system comprising at least three stars. Delta¹ (7 Canis Minoris) is a white giant. Delta² (8 Canis Minoris) and delta³ (9 Canis Minoris) are white main sequence (dwarf) stars.

11 Canis Minoris is a white dwarf star which has a meteor shower named after it, due to it appearing to hail from that direction. However, the meteor shower is due to the Earth passing through the trail of debris left by a passing comet, and has nothing to do with the actual star.

YZ Canis Minoris is a UV Ceti-class flare star red dwarf. It is giving off large flares, which is exciting some astrophysicists analysing the data from the Einstein X-ray Observatory, the International Ultraviolet Explorer and the Very Large Array.

Meteor Showers

The 11 Canis-Minorids  meteor shower was first noted in December 1964 by KB Hindley, who had been hoping to catch some stray Geminids. He noted 26 meteors in an observation time of just under four hours, determining that at least a fifth were hailing from the direction of 11 Canis Minoris. Tracing back the trajectory gives us a parent comet of Nicollet-Pons (C/1821 B1), although since 1970 some astronomers reference the comet Mellish (D/1917 F1) as the one responsible. The suggested duration is 4 - 15 December with a maximum (when your chances of viewing some are the highest) between 7-9 December, but it is extremely sparse now.

Extrasolar Planets in Canis Minor

The nomenclature that has been decided upon for extrasolar planet discoveries is to use a lower-case letter after the parent star catalogue number (or name), eg 'HD 66141 b'. This stays with the planet even if more discoveries are made within the same solar system, and despite the position of the new planet relative to the star.

HD 66141 b is a superjovian world in orbit around an orange giant star. HAT-P-50 b is a Jupiter-mass world which orbits its star in just over three days.

Small Dogs in Modern Culture

While this Entry is primarily about Canis Minor the constellation, the author thought you might like to read some more information about small dogs in general, particularly ones with large hearts.

• Greyfriars Bobby was a loyal and devoted Skye Terrier who fully deserves his own place in the Edited Guide.

• In the world of Futurama, the episode entitled 'Jurassic Bark' tells the story of Fry's dog Seymour, who waits in vain for Fry to return, eventually dying 12 years later. It is thought the writers drew inspiration from the true tale of Greyfriars Bobby. Adding the song 'I Will Wait For You', by Connie Francis, to the closing credits made it a guaranteed tear-jerker. 'Jurassic Bark' is consistently voted the overall favourite episode of fans whenever there is a new poll.

• The fourth incarnation of Doctor Who had a faithful robotic canine companion called K-9, who now guest-stars in the spin-off The Sarah Jane Adventures with fellow ex-companion Sarah Jane Smith.

• Hachi-ko was an Akita who accompanied his master to the train station on workdays, and was always there to meet him upon his return. Unfortunately, the owner passed away while at work and the dog continued to show up at the station for ten years, until his own death. The Japanese were so moved by this story of devotion and faithfulness that they installed a statue of Hachi-ko at the Shibuya Station in Tokyo. The statue has gained recognition as a meeting place for secret lovers and new friends.

• One of the most recognisable small dogs is 'Nipper' (1884 - 1895), the dog looking down the phonograph horn in the HMV logo. Nipper was fascinated by the voice emanating from the gramophone whenever a record was playing, and used to sit listening attentively. His owner's brother-in-law, a painter called Francis Barraud, could not forget the stance and painted the scene from memory three years after the dog's demise. The imaginatively entitled Dog Looking at and Listening to a Phonograph was registered in 1899. Nipper was buried in a back garden in Kingston-upon-Thames which is now a bank car park.