Pollux
What is Pollux?
Stars· Distance 33.8 ly · size 8.8× Sun. The brighter of the two Gemini twins. It is the nearest giant star to the Sun and has a planet heavier than Jupiter. Its orange colour, from a surface of about 4,670 K, sets it apart from white Castor.
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Distance and spectral type
Pollux is about 34 light-years away, a orange bright giant (spectral type K0IIIvar), in the constellation Gemini. Its apparent magnitude is 1.1, visible to the naked eye.
Stellar figures
| Distance | 33.8 ly |
|---|---|
| Magnitude | 1.14 — seventeenth brightest |
| Type | K0 orange giant |
| Surface temperature | ~4,670 K (Sun 5,772 K) |
| Planet | Pollux b (2.3 Jupiters, 590 days) |
Figures are representative approximations. Source: compiled from NASA and IAU public data.
Behind the name
The immortal twin, who begged Zeus to share his immortality with Castor. It hosts a planet.
From Pollux, the Sun is a faint star in Sagittarius
What would the Sun look like from Pollux? The calculation says it would be a faint star of about magnitude 4.9. It could just be seen with the naked eye under a dark country sky, but not under city lights. It would appear in Sagittarius, because that constellation lies directly opposite Gemini in our sky. Pollux, by contrast, shines as a bright first-magnitude star in our sky.
Across the same 33.8 light-years, the difference comes from how much light each star gives off. Pollux, a swollen giant, shines 43 times as brightly as the Sun. The Sun is now an ordinary star burning hydrogen in its core, but in about five billion years it is expected to run low on that fuel and swell into a giant. The Sun will then become a large, orange-tinted star much like Pollux today, and it will look brighter from far away.
The star in depth
Pollux is the brightest star in Gemini, the Twins. It carries the label Beta, meaning the constellation's second star, yet it is brighter than Alpha, Castor. At magnitude 1.14 it is the seventeenth-brightest star in the night sky. In Greek myth, Pollux was a son of Zeus and the twin who could not die, while his brother Castor was mortal.
Pollux is 33.8 light-years away, making it the nearest giant star to the Sun. A giant is an older star that has used up the hydrogen in its core and swollen. Pollux has 1.9 times the Sun's mass, but it has grown to 8.8 times the Sun's width and 43 times its brightness. Its surface is about 4,670 K, roughly 1,000 degrees cooler than the Sun's, which is why it looks orange.
Pollux has a planet. In 2006 astronomers confirmed a planet about 2.3 times as massive as Jupiter circling Pollux every 590 days. They found it by spotting the small wobble the planet causes in the star. The planet is called Pollux b, and in a 2015 naming contest run by the International Astronomical Union it received the name Thestias.
From December to March, look high in the eastern evening sky, above and to the left of Orion, for two stars of similar brightness side by side. The slightly brighter, orange one is Pollux; the white one is Castor. In the Sky view, choose a February night and select Gemini to see both. On the size ladder you can place Pollux beside the Sun to compare their sizes.
Frequently asked
- How far is Pollux from Earth?
- The distance of Pollux is 33.8 ly.
- How bright is Pollux (apparent magnitude)?
- The magnitude of Pollux is 1.14 — seventeenth brightest.
- What kind of object is Pollux?
- Pollux is a K0 orange giant.
- What is the temperature of Pollux?
- The surface temperature of Pollux is ~4,670 K (Sun 5,772 K).
- Which constellation is Pollux in?
- Pollux lies in the constellation Gemini.
Related
Figures are representative approximations. Simulated positions use J2000 mean elements.