Hadar
What is Hadar?
Stars· Distance ~390 ly · size 9× Sun. The second Pointer star, beside Alpha Centauri, aiming at the Southern Cross. Eleventh brightest in the sky, it is a triple system of hot blue giants 390 light-years away — a guide star for southern navigators, invisible from Korea.
📍 Visible from where you are right now — computed in your browser
bearing · altitude · rise time · best time tonight
Where Hadar is in your sky right now: https://nowsky.org/solar/sky?sel=hadar — location and time set automatically, no login.
Distance and spectral type
Hadar is about 392 light-years away, a blue-white bright giant (spectral type B1III), in the constellation Centaurus. Its apparent magnitude is 0.6, visible to the naked eye.
Stellar figures
| Distance | ~390 ly |
|---|---|
| Magnitude | 0.61 — eleventh brightest |
| Type | B1 blue giant, triple |
| Constellation | Centaurus |
Figures are representative approximations. Source: compiled from NASA and IAU public data.
Behind the name
Arabic "ground". With Alpha Centauri it forms the Pointers to the Southern Cross.
Frequently asked
- How far is Hadar from Earth?
- ~390 ly.
- How bright is Hadar (apparent magnitude)?
- 0.61 — eleventh brightest.
- What kind of object is Hadar?
- B1 blue giant, triple.
- Which constellation is Hadar in?
- Centaurus.
- Where is Hadar 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 Southern Cross pointers, and how to tell the real cross
The southern sky holds two "false crosses" easily confused with the Southern Cross — larger, fainter cross shapes made of stars in Carina and Vela. The key to the real one is Hadar and Alpha Centauri: extend the line joining them westward four and a half times and it reaches Gacrux at the top of the true cross, and no such bright pointers stand beside the false ones.
Extending the long axis of the Southern Cross four and a half times downward lands near the south celestial pole, giving south; the point where that line meets the perpendicular bisector of the two pointers marks the pole more precisely. This is basic navigation and camping craft in the southern hemisphere, and the reason the cross appears on the flags of New Zealand, Australia and Brazil is exactly this role as a landmark. Set the sky view to Sydney and the arrangement of Hadar, Alpha Centauri and the cross appears as it is.
The star in depth
Hadar, Beta Centauri, also called Agena, is the eleventh-brightest star in the night sky at magnitude 0.61. About 390 light-years away, it is a B1 III blue giant with a surface temperature of 25,000 K and more than ten solar masses. Where its neighbour Alpha Centauri is a Sun-like star, Hadar pours out around 40,000 Suns of light; the two appear side by side only by chance, their distances differing ninety-fold.
It is really a triple system. Two massive primaries, Aa and Ab, orbit each other every 357 days, while a third star, B, circles far outside. Both primaries are pulsating Beta Cephei variables whose brightness flickers slightly over a few hours. Such massive stars live only tens of millions of years and are expected to end as supernovae. The Arabic name Hadar means ground; Agena means the knee.
At declination −60° it cannot be seen from Korea. In the southern hemisphere it sits 4.5° from Alpha Centauri, and together the two Pointers aim along the long axis of the Southern Cross, standing high in the south on April to June evenings. In the Sky view, switch the location to Sydney or Cape Town to find Hadar shining blue-white beside Alpha Centauri.
Related
Figures are representative approximations. Simulated positions use J2000 mean elements.