# Tiaki (Beta Gruis)

Tiaki (Beta Gruis) is a star in the constellation Grus, magnitude 2.1.

**A cool red giant in the Crane, glowing brightest in infrared, with a Polynesian name.**

Tiaki carries a name from the Tuamotu islands of French Polynesia, adopted by the International Astronomical Union in 2017. It has changed constellations too: medieval Arab astronomers counted it as the last star in the tail of the Southern Fish, before it became part of the Crane.

It is a red giant late in life, about 2.4 times the Sun’s mass but swollen to some 150 times its width. Its surface is only about 3,500 kelvin, just over half as hot as the Sun’s, which gives it a dull red [colour](https://astropilot.space/glossary/star-colour). Even so it pours out about 3,200 times the Sun’s energy, much of it as infrared: at near-infrared wavelengths it is the fifth-brightest star in the night sky.

Tiaki also changes. Alan Cousins announced in 1952 that it is a [variable star](https://astropilot.space/glossary/variable-star). It brightens and fades by about 0.4 magnitude, sometimes on a regular 37-day rhythm, sometimes slowly and irregularly.

Tiaki (Beta Gruis) is 180 light-years away: the light we see from it set off around 1845, around the time Neptune was discovered.

## Did you know?

- **If it replaced the Sun.** At around 150 times the Sun’s radius, Tiaki would reach almost to the orbit of Venus if it sat at the centre of our Solar System.
- **Second Star of the Crane.** Chinese astronomers saw a crane here too: Beta Gruis is Hè èr, the Second Star of the Crane — the source of its old English name, Ke.

A red-orange 2nd-magnitude star in Grus, the Crane, a few degrees from blue-white Alnair. The two make a fine colour contrast to the naked eye or in binoculars; Tiaki also varies slightly, so compare their brightness now and then.

## When and where to see it

It is best placed in the evening sky around October, when it crosses the meridian at about 10 pm local time (around midnight in September). It can be seen from everywhere south of 43°N and never sets south of 43°S.

At its highest it stands below the horizon from 50°N, 8° up from 35°N, 43° up from the equator, 78° up from 35°S.

## Facts

- Type: Star
- Constellation: Grus
- Designations: Beta Gruis, β Gru, HR 8636, HD 214952, HIP 112122
- Magnitude: 2.1
- Position: RA 22h 42.7m, Dec −46° 53′ (J2000)
- Spectral type: M4.5III
- Colour: orange-red (B−V 1.62)
- Distance: 180 light-years
- Discovered: Naked-eye star; Alan Cousins announced its variability in 1952

Open AstroPilot to see when Tiaki (Beta Gruis) is highest tonight from your location, how easy it is with your telescope or binoculars, and an eyepiece view. https://astropilot.space/object/tiaki