Pollux

What is Pollux?

Stars· Distance 33.8 ly · size 8.8× Sun. The brighter of the Twins. The nearest giant star to the Sun, and the first first-magnitude star found to host a planet larger than Jupiter. On winter nights it shines beside Castor above and left of Orion, its orange tint — a surface of about 4,670 K — setting it apart from its white twin.

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Pollux
Image: NowSky rendering (an illustration, not a photograph)· Wikipedia

Where Pollux is in your sky right now: https://nowsky.org/solar/sky?sel=pollux — location and time set automatically, no login.

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

Distance33.8 ly
Magnitude1.14 — seventeenth brightest
TypeK0 orange giant
Surface temperature~4,670 K (Sun 5,772 K)
PlanetPollux 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.

Frequently asked

How far is Pollux from Earth?
33.8 ly.
How bright is Pollux (apparent magnitude)?
1.14 — seventeenth brightest.
What kind of object is Pollux?
K0 orange giant.
What is the temperature of Pollux?
~4,670 K (Sun 5,772 K).
Which constellation is Pollux in?
Gemini.
Where is Pollux in the sky right now?
Open the sky view for your location and time and it shows the position in the sky right now.

The Sun from Pollux — a 5th-magnitude star in Sagittarius

Reverse the 33.8 light-years and look back from Pollux, and the Sun is a faint star of magnitude 4.9 — within naked-eye reach, but easily lost under a city sky — in the direction of Sagittarius, the point opposite Gemini. If Pollux b is real and had an observer, the Sun would be one point among the crowd of stars toward the galactic centre.

Pollux, by contrast, is a first-magnitude star in Earth's sky, because it is twice the Sun's mass and has swelled into a giant 43 times as luminous. Its diameter is nine times the Sun's and its surface, at 4,670 K, about a thousand degrees cooler, hence the orange tint. The Sun will pass through a similar stage in five billion years, so Pollux is close to a portrait of the Sun's future, visible in the winter sky.

The star in depth

Pollux is Beta Geminorum, yet it outshines Alpha, Castor, at magnitude 1.14 — the seventeenth-brightest star in the night sky. At 33.8 light-years it is the nearest giant star to the Sun, a K0 III of 1.9 solar masses, 8.8 solar radii and 43 solar luminosities. With a surface of 4,600 K it glows orange, settled in the stable helium-burning stage of a giant's life.

In Greek myth Pollux (Polydeuces) was the immortal twin, son of Zeus, while Castor was the mortal brother. In 2006 a planet of 2.3 Jupiter masses, Pollux b, was confirmed orbiting every 590 days — the first planet found around a first-magnitude star. The planet was later named Thestias in an International Astronomical Union public naming contest. Pollux also shows a weak magnetic field and X-ray emission.

From December to March look high in the east, above and left of Orion, where Pollux and Castor stand 4.5° apart; Pollux is slightly brighter and orange, Castor white. In the Sky view, set a February night and select Gemini to see the pair. The 3D neighbourhood view shows Pollux 33.8 light-years out, and the size ladder compares its 8.8-Sun diameter with our star.

Related

Figures are representative approximations. Simulated positions use J2000 mean elements.