Canis Minor
What is Canis Minor?
Constellations· Winter evenings (N) · eastern corner of the Winter Triangle. Orion's smaller hunting dog. It has only two bright stars, but Procyon completes the Winter Triangle with Betelgeuse and Sirius. Its name means before the dog, because it rises a little ahead of Sirius.
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Stars of the figure
| Star | Magnitude |
|---|---|
| Procyon | 0.4 |
The 1 brightest of the 2 stars used in the figure (1 lines). Lower magnitude means brighter.
Constellation basics
| Season | winter evenings, January–March |
|---|---|
| Brightest star | Procyon (0.4) |
| How to find | the star completing an equilateral triangle with Betelgeuse and Sirius |
| Area rank | 71st of 88 |
Figures are representative approximations. Source: compiled from NASA and IAU public data.
A companion found by calculation before anyone saw it — Procyon B
In 1844 the German astronomer Friedrich Bessel found that Sirius and Procyon did not move across the sky in straight lines but wobbled as they went. He concluded that each was being tugged by an unseen, heavy companion. The companion of Sirius was found in 1862, but Procyon's was much fainter and had to wait half a century, until John Schaeberle spotted it in 1896 with the large telescope at Lick Observatory in the United States.
Procyon B is a faint white dwarf of about 11th magnitude. It sits only about five arcseconds from brilliant Procyon and is lost in its glare, so even today separating the two takes a large telescope and special techniques. Its existence was predicted from the pull of gravity before anyone saw it, and the prediction proved right, which makes it an early example of its kind in the history of astronomy.
The constellation in depth
Canis Minor is the second of Orion's hunting dogs. Another tale makes it Maera, the faithful dog who led her master's daughter to her father's grave. The Greeks saw this star, which rises a little before Sirius, as the dog's forerunner, which is why it was named Procyon, before the dog.
Procyon is a nearby star about 11.5 light-years away. It is a little larger and brighter than the Sun and has nearly used up the hydrogen in its core, so it has begun to swell. Like Sirius, it has a small white-dwarf companion, Procyon B, and the two circle each other about every 40 years. With only Procyon and Gomeisa bright enough to notice, the constellation is drawn as a single line, one of the simplest figures in the sky.
On winter evenings, first find red Betelgeuse in Orion and Sirius to its south-east. The bright star to the east that makes a nearly equilateral triangle with them is Procyon, and the three form the Winter Triangle. Gomeisa sits close to Procyon's north-west. With the Sky view set to a February evening, the whole triangle fits on one screen.
Frequently asked
- When can I see Canis Minor?
- Canis Minor is best seen in winter evenings, January–March.
- How do I find Canis Minor?
- To find Canis Minor, look for the star completing an equilateral triangle with Betelgeuse and Sirius.
- What is the brightest star in Canis Minor?
- The brightest star in Canis Minor is Procyon, at magnitude 0.4.
Related
Figures are representative approximations. Simulated positions use J2000 mean elements.