COSMOS / CONSTELLATIONS / ARA
Ara (Altar)
The Altar. IAU abbreviation Ara. One of the 48 classical constellations listed by Ptolemy in the Almagest in the 2nd century AD.
STAR CHART
KEY FACTS
- IAU abbreviation
- Ara
- Latin name / genitive
- Ara / Arae
- Position
- Right ascension ≈ 17 h 18 m; declination −67° to −46°
- Visibility from Türkiye
- From Türkiye only its northern part is seen, low on the southern horizon; the southern provinces are better placed.
- Best time to observe
- Best placed at 21:00 Türkiye time around 8 August.
- Number of stars
- 73 stars brighter than magnitude 6.5 in the catalogue; 10 brighter than 5 and 7 brighter than 4.
INTERACTIVE LAB
Where is Ara tonight?
Only the northern part of this constellation is seen from Türkiye, low on the southern horizon. The lab opens for Ankara on today’s date; switch the city to Antalya and then to Sydney and watch how the “Visible part” row and the chart change. The “Best night” button jumps to the best date (around 8 August).
MYTH, HISTORY AND OBSERVING
In Greek lore this is the altar on which the gods swore allegiance before their war against the Titans. It lies on the Milky Way south of Scorpius’ tail and contains NGC 6397, one of the closest globular clusters to Earth. From Türkiye only part of it rises, just above the southern horizon.
BRIGHTEST STARS
| Star | Magnitude | Distance (light-years) | Spectral type |
|---|---|---|---|
| β Ara | 2.84 | 646 | K3Ib-II |
| α Ara | 2.84 | 267 | B2Vne |
| ζ Ara | 3.12 | 486 | K5III |
| γ Ara | 3.31 | 1,113 | B1Ib |
| δ Ara | 3.60 | 198 | B8V |
| θ Ara | 3.65 | 813 | B2Ib |
| η Ara | 3.77 | 299 | K5III |
| ε¹ Ara | 4.06 | 361 | K4III |
Magnitude: apparent brightness; the smaller the number, the brighter the star. Distances derive from parallax measurements and are uncertain for distant stars. Source: HYG v4.1 star catalogue (CC BY-SA 4.0).
SOURCES
Position, visibility and best observing time were computed approximately for this page from the catalogue stars (Ankara, 39.9° N). The 88 constellations were adopted by the IAU in 1922; their boundaries were drawn by Eugène Delporte in 1930.