Canopus
What is Canopus?
Stars· Distance 310 ly · size 71× Sun. The second-brightest star in the night sky, shining ten thousand Suns from 310 light-years away and used by spacecraft as a navigation reference. It rides low in the south, so from Korea it barely clears the horizon on winter nights.
📍 Visible from where you are right now — computed in your browser
bearing · altitude · rise time · best time tonight
Where Canopus is in your sky right now: https://nowsky.org/solar/sky?sel=canopus — location and time set automatically, no login.
Distance and spectral type
Canopus is about 309 light-years away, a yellow-white supergiant (spectral type F0Ib), in the constellation Centaurus. Its apparent magnitude is -0.7, visible to the naked eye.
Stellar figures
| Distance | 310 ly |
|---|---|
| Magnitude | −0.74 — second brightest star |
| Type | A9 bright giant |
| Constellation | Carina |
Figures are representative approximations. Source: compiled from NASA and IAU public data.
Behind the name
Named for Menelaus's helmsman in the Trojan War. The second-brightest star, used by spacecraft as a navigation reference.
Frequently asked
- How far is Canopus from Earth?
- 310 ly.
- How bright is Canopus (apparent magnitude)?
- −0.74 — second brightest star.
- What kind of object is Canopus?
- A9 bright giant.
- Which constellation is Canopus in?
- Centaurus.
- Where is Canopus in the sky right now?
- Open the sky view for your location and time and it shows the position in the sky right now.
Ten thousand Suns — where the brightness comes from
Canopus is a bright giant of spectral type A9 II. Its radius is 71 times the Sun's and its surface, at 7,400 °C, is hotter than the Sun's; together they give a luminosity more than ten thousand times solar. With about eight solar masses it appears to have exhausted the hydrogen at its core and be burning helium, and such stars sit on a "blue loop" between red and blue giant phases, so its colour may change again.
Magnitude −0.74 from 310 light-years means that Sirius (8.6 light-years) placed at Canopus's distance would be a barely visible 5th-magnitude star. Had Canopus been in the solar neighbourhood it would be the brightest object in the sky after the Sun and Moon. Its age is around 25 million years, a two-hundredth of the Sun's, and because its mass sits at the supernova threshold of about eight Suns, whether it ends as a supernova or a white dwarf is undecided.
The star in depth
Canopus is Alpha Carinae, and at magnitude −0.74 the second-brightest star in the night sky after Sirius. Sirius is bright because it is close; Canopus is genuinely brilliant. From 310 light-years it radiates about ten thousand times the Sun's light, and its radius of 71 Suns would fill a third of Mercury's orbit. It is an A9 bright giant with a surface near 7,400 K and a mass roughly eight times the Sun's.
The name is said to honour the helmsman of the Spartan fleet in the Trojan War, and helmsmanship stuck: spacecraft star trackers use Canopus as a reference because it is bright and far from the ecliptic, so nothing else can be mistaken for it. Voyager and many other probes fixed their orientation on the Sun and Canopus. The star appears to be burning helium in its core; it is a little too light to explode as a supernova and will probably end as a massive white dwarf.
At declination −53° it never rises for Seoul. From Jeju or the south coast, look just above the southern horizon around midnight in January or February to catch it briefly below Sirius; in the southern hemisphere it rules the summer sky. In the Sky view, switch the location to a southern city such as Sydney to see Canopus riding high beside Sirius, and compare its diameter with the Sun and Sirius on the size ladder.
Related
Figures are representative approximations. Simulated positions use J2000 mean elements.