When is the best time to observe Unukalhai?

Unukalhai is best observed from April through June, with peak visibility during May when it transits around midnight in the Northern Hemisphere.

Where is Unukalhai located in the sky?

Unukalhai lies in the constellation Serpens at right ascension 15h 44m and declination +06° 26′.

What telescope do I need to see Unukalhai?

At magnitude 2.6, Unukalhai is visible to the naked eye from dark skies, easy in any binoculars.

Unukalhai — Star in Serpens

HIP 77070; Alpha Serpentis; 24 Serpentis

Magnitude 2.6^m Star Serpens (Ser) Visible

Star Map + List + Plan

About Unukalhai

Description

Unukalhai is an orange giant of spectral type K2III at magnitude 2.65, the brightest star in Serpens. Located about 74 light-years from Earth, it has a luminosity of roughly 70 times solar. Serpens is unique as the only constellation divided into two parts — Serpens Caput (head) and Serpens Cauda (tail) — separated by Ophiuchus, and Unukalhai lies in the head.

Observing Tips

Unukalhai is the brightest star in the head of the serpent (Serpens Caput), west of Ophiuchus. Its warm orange color helps identify it. It forms a rough triangle with Arcturus and Alphecca. Best observed May through August.

History

The name Unukalhai comes from the Arabic 'unuq al-hayyah,' meaning 'the neck of the serpent.' Serpens represents the snake held by Ophiuchus (Asclepius) and is the only constellation split into two separate parts.

Fun Facts

Serpens is the only constellation that comes in two pieces — Serpens Caput and Serpens Cauda, separated by Ophiuchus in the middle. Unukalhai anchors the head, while the famous Eagle Nebula (M16) lies in the tail.