The constellation Cepheus the King can only boast of one second-magnitude star. That star is Alderamin (Alpha Cephei). It’s by far the constellation’s brightest star, lighting up the bottom corner of an otherwise faint house-shaped pattern of stars.
On a dark night, Alderamin is easily visible and also relatively easy to find. Look first for the W or M-shaped constellation Cassiopeia the Queen. Then use the Cassiopeia stars Schedar and Caph to star-hop to Alderamin.
Schedar: Short life of burning bright
Sky chart of the constellation Cepheus the King
If we wish to contrast Alderamin to our sun, it deserves to be called a respectably bright star. According to the star expert Jim Kaler, Alderamin shines with the luminosity of 18 suns. But Alderamin recedes to almost nothing, if we contrast it with Cepheus’ two king-sized stars: Mu Cephei (the Garnet Star) and VV (two V’s) Cephei. Although both of these stars appear faint, only visible to the unaided eye on a dark, moonless night, it’s because they’re so distant, residing a few thousand light-years away.
Sky chart: Wikimedia Commons. Click here for a larger version
Alderamin is fairly close to our solar system, at 49 light-years distant. Therefore, it shines more brightly in our sky than do the more intrinsically luminous stars Mu Cephei and VV Cephei. These two supergiants are among the largest and brightest in our Milky Way galaxy, shining with the firepower of hundreds of thousands of suns. If either star were to replace the sun in our solar system, its diameter would extend beyond the orbit of the planet Jupiter, which lies a good five times farther out from the sun than Earth does.
If you’re game, Alderamin can help guide you to Cepheus’ two faintly visible supergiant stars: Mu Cephei and VV Cephei. Click here for a more detailed view of Cepheus. By the way, Alderamin will be the North Star some 5500 years from now, around 7500 AD.
