Canis Major

Canis Major

Constellation
List of stars in Canis Major
Abbreviation	CMa
Genitive	Canis Majoris
Pronunciation	/ˌkeɪnɨs ˈmeɪdʒər/, genitive /ˈkeɪnɨs məˈdʒɒrɨs/
Symbolism	the greater dog
Right ascension	7
Declination	−20
Area	380 sq. deg. (43rd)
Main stars	8
Bayer/Flamsteed stars	32
Stars with known planets	4
Bright stars	5
Nearby stars	1
Brightest star	Sirius (α CMa) (−1.46m)
Nearest star	Sirius (α CMa) (8.6 ly)
Messier objects	1
Meteor showers	None
Bordering constellations	Monoceros Lepus Columba Puppis
Visible at latitudes between +60° and −90°. Best visible at 21:00 (9 p.m.) during the month of February.

An image of Canis Major (top right) as seen from an airplane. Note that in this position the dog is nearly upright. At the moment of exposure the plane hovered above about 8 degrees north latitude (Andaman Sea west of Thailand).

Canis Major is a constellation, included in the 2nd century astronomer Ptolemy's 48 constellations, and still included among the 88 modern constellations. Its name is Latin for 'greater dog', and is commonly represented as one of the dogs following Orion the hunter (see also Canis Minor the 'lesser dog'). Canis Major contains Sirius, the brightest star in the night sky, known as the 'dog star'; that star is part of the asterism known as the Winter Triangle in the Northern Hemisphere, or the Summer Triangle in the Southern.

Notable features

There are several other fairly bright stars (in order of brightness) in Canis Major, all with Arabic names:

• ε CMa: (1.51v) Adhara – Virgins
• δ CMa: (1.83) Wezen – The Weight
• β CMa: (1.98v) Murzim – The Announcer
• η CMa: (2.45v) Aludra – the virgin
• ζ CMa: (3.02) Furud – Bright Single One
• γ CMa: (4.11) Muliphen – the Arabic rendering of the Greek for "dog's ear".

Deep sky objects

There are not many bright deep sky objects in this region of sky. The only Messier object in Canis Major is Messier 41 (NGC 2287), an open cluster of visual magnitude 4.6. It is located about 4 degrees directly south of Sirius. Messier 41 is roughly 2350 light years away from Earth, contains about 8,000 stars, and is about 24 light years in diameter. It is also noted for containing a number of K-class stars.

The band of the Milky Way goes through Canis Major and therefore background galaxies are hidden behind interstellar dust clouds. However, in 2003, Canis Major Dwarf, the closest satellite galaxy to Earth, was found within the constellation.

History

In Europe, Canis Major has been associated with dogs from early times. The name of Sirius, its brightest star, means "scorching star", since the summer heat occurred just after Sirius' heliacal rising. The Ancient Greeks referred to such times in the summer as dog days, as only dogs would be mad enough to go out in the heat, leading to the star being known as the Dog Star. Consequently, the constellation was named after it, as 'The Big Dog'.^{[citation needed]}

Mythology

In early classical Europe, Canis Major represented the dog^[1] Laelaps, a gift from Zeus to Europa; or sometimes the hound of Procris, Diana's nymph; or the one given by Aurora to Cephalus, so famed for its speed that Zeus elevated it to the sky.

It was also considered to represent Orion's hunting dog, pursuing Lepus the Hare or helping Orion fight Taurus the Bull; and is referred to in this way by Aratos, Homer and Hesiod. The ancient Greeks refer only to one dog, but by Roman times, Canis Minor appears as Orion's second dog.^{[citation needed]}

Sirius was considered a dog in its own right, early Greek mythology sometimes the constellation to represent a two-headed dog. As such, together with the area of the sky that is deserted (now considered as the new and extremely faint constellations Camelopardalis and Lynx), and the other features of the area in the Zodiac sign of Gemini (i.e. the Milky Way, and the constellations Gemini, Orion, Auriga, and Canis Minor), this may be the origin of the myth of the cattle of Geryon, which forms one of The Twelve Labours of Heracles.^{[original research?]}

Roman myth refers to Canis Major as Custos Europae, the dog guarding Europa but failing to prevent her abduction by Jupiter in the form of a bull; and as Janitor Lethaeus, the watchdog.^{[citation needed]}

Visualizations

Canis Major as depicted in Urania's Mirror, a set of constellation cards published in London c.1825. Next to it are Lepus and Columba (partly cut off).

Depending on the faintness of stars considered, Canis Major can be shown to resemble a dog facing either above or below the ecliptic.^{[citation needed]}

See also

• Canis Minor
• Isis
• Sirius
• Anubis
• Laelaps

Notes

References

• Ian Ridpath and Wil Tirion (2007). Stars and Planets Guide, Collins, London. ISBN 978-0007251209. Princeton University Press, Princeton. ISBN 978-0691135564.

External links

Wikimedia Commons has media related to: Canis Major

• The Deep Photographic Guide to the Constellations: Canis Major
• Star Tales – Canis Major

Coordinates: 07^h 00^m 00^s, +20° 00′ 00″