Red giant · Sagittarius
η Sagittarii
Also known as: η Sgr, HIP 89642
mag 3.1150 light-years
About
η Sagittarii is a red giant of magnitude 3.1 in Sagittarius, about 150 light-years away.
How to find it
- η Sagittarii is in the constellation Sagittarius.
- Best evenings: around mid-August it is highest at about 9 pm (10 pm in summer time); a month earlier, two hours later.
- Where on Earth: it is seen well, at least 10° up, from south of 43° N.
When it rises and sets tonight, how high it climbs and how much the Moon gets in the way are worked out in your browser for your place.
What you will see
- EyesVisible from the suburbs on a clear night, but lost in bright city skies.
- Binoculars (10×50)A sharp point; binoculars bring out its colour and the fainter stars around it.
- Telescope (6–8 inch)Still a point of light at any magnification — stars are too far away to show a disc. Low in the sky, bright stars twinkle and flash colours.
Stars look the same in any instrument: brighter and sharper, but never bigger.
Facts
| Designation | η Sagittarii (η Sgr) |
|---|---|
| Hipparcos number | HIP 89642 |
| Type | Red giant |
| Spectral type | M2III |
| Colour | Orange-redB−V colour index 1.58 |
| Magnitude | 3.1The smaller the number, the brighter. |
| Distance | 150 light-yearsThe light you see left it around 1880. |
| Proper motion | 0.21″ per year across the sky |
| Constellation | Sagittarius |
| Right ascension (J2000) | 18h 17m 37.7s |
| Declination (J2000) | −36° 45′ 42″ |
Sources and credits
Star data: HYG Database by David Nash, CC BY-SA 4.0. All data sources →