Beta Draconis (Rastaban): The Dragon’s Eye

In the sinuous northern constellation of Draco the Dragon, a bright, golden-hued beacon marks the head of the mythical beast: Beta Draconis, also known by its traditional name Rastaban. The name Rastaban, derived from the Arabic ra’s ath-thu’ban (“head of the serpent” or “dragon”), reflects its position in the quadrilateral of stars forming the dragon’s head, alongside Gamma Draconis (Eltanin), Nu Draconis, and Xi Draconis.

Picture of the sky showing where Beta Draconis is found. — Arrow points to Beta Draconis. Beta Draconis, and the bright star above it, Eltanin, make up the Dragon’s eyes. Credit: Stellarium

A Golden Giant

Beta Draconis shines with an apparent magnitude of about 2.8, making it one of Draco’s brightest stars and an easy naked-eye target. Its warm yellow glow comes from its classification as a G2Ib-II star—a bright giant verging on a supergiant. According to Jim Kaler, this means it has already burned through the hydrogen in its core and has expanded to a size nearly 40 times the Sun’s diameter! Located roughly 380 light-years away, Beta Draconis blazes with about 950 times the Sun’s luminosity, its light crossing centuries before reaching our eyes.

A Hidden Companion

Though it appears as a single point of light to the unaided eye, Beta Draconis is actually a double star system. Separated by only about 4.2 arcseconds on the sky, the two stars orbit at a distance that makes the secondary difficult to spot without good seeing conditions and moderate magnification. Together, they form a pairing that blends the brilliance of an evolved giant with the quiet steadiness of a fainter stellar partner.

Next time you find yourself scanning the northern sky, let your eyes settle on Draco’s head. That warm light is Beta Draconis—a timeless golden eye watching over the dragon’s eternal coil.

My Observations

Date	July 3, 2023
Time	11:20 p.m.
Location	Seattle, WA
Magnification	338x
Scope	Meade 8″ SCT
Eyepiece	6mm
Seeing	Above Average
Transparency	Above Average

Sketch of Beta Draconis double star in Draco. The drawing shows the bright primary star and the very dim companion. Also known as Bet Dra, Rastaben, Alwaid, Asuia, SAO 30429, HD 159181, 23 Dra, β Dra, 23 Draconis, HIP 85670, HR 6536, BU 1090 — Sketch of Beta Draconis on a July night

Fireworks are lighting up the neighborhood around me on this pre-Independence Day evening. I can hear the whistle of rockets and the pop of firecrackers in the distance, but my focus remains on a more distant and ancient display of light.

I center the scope on my target, the double star Beta Draconis, but the pair refuses to resolve at lower magnification. I break out my 6mm eyepiece, and as I bring the image into focus, the single point of light splits in two. The faint companion star pops into view, a tiny, steadfast, and very dim pinpoint next to its brilliant sibling, perfectly separated against the night sky.

Key Stats

Constellation	Draco
Best Viewing	Summer
Visual Magnitude	+2.79 \| +14
Separation	4.57″
Position Angle	16.9°
Distance	380 ly
My Viewing Grade	B-
Designations	Bet Dra, Rastaben, Alwaid, Asuia, SAO 30429, HD 159181, 23 Dra, β Dra, 23 Draconis, HIP 85670, HR 6536, BU 1090