When is the best time to observe Alderamin?

Alderamin is best observed from July through September, with peak visibility during August when it transits around midnight in the Northern Hemisphere.

Where is Alderamin located in the sky?

Alderamin lies in the constellation Cepheus at right ascension 21h 19m and declination +62° 35′.

What telescope do I need to see Alderamin?

At magnitude 2.4, Alderamin is visible to the naked eye under most conditions.

Alderamin — Star in Cepheus

HIP 105199; Alpha Cephei; 5 Cephei

Magnitude 2.4^m Star Cepheus (Cep) Visible

Star Map + List + Plan

About Alderamin

Description

Alderamin is a white main-sequence star of spectral type A7V at magnitude 2.44, the brightest star in Cepheus. Located about 49 light-years from Earth, it has a luminosity of roughly 17 times solar. Alderamin is a rapid rotator, spinning at about 246 km/s. It will become the pole star around AD 7500 as Earth's axis precesses.

Observing Tips

Alderamin marks the western wall of the house-shaped Cepheus, near Cassiopeia and the north celestial pole. It is circumpolar from mid-northern latitudes and visible year-round. The constellation Cepheus is best identified by its distinctive pentagonal house shape. Best placed in the evening sky from August through December.

History

The name Alderamin comes from the Arabic 'al-dhira' al-yamin,' meaning 'the right forearm.' Due to precession, Alderamin will be the north pole star around AD 7500, taking over the role currently held by Polaris. It has served as a rough pole star in the past as well.

Fun Facts

Alderamin has served as a rough pole star multiple times in the 26,000-year precession cycle and will do so again around AD 7500. Its rapid rotation suggests it may be a relatively young star or may have been spun up by some process.