Eltanin is an orange giant of spectral type K5, lying 148 light years away. Despite its Bayer designation of "gamma," it is actually the brightest star in Draco, outshining Rastaban (Beta Draconis) by nearly half a magnitude. In fact, the name "Rastaban" was formerly used for Eltanin, and the two terms share an Arabic root meaning "serpent" or "dragon." Its proximity to the point directly overhead of London has also earned it the name "Zenith Star."

In 1.5 million years, Eltanin will pass within 28 light years of Earth. At this point it will be the brightest star in the night sky, nearly as bright as Sirius (assuming its current absolute magnitude does not change).

In 1728, while unsuccessfully attempting to measure the parallax of this star, James Bradley discovered the aberration of light resulting from the movement of the Earth. Bradley's discovery proved Copernicus' theory that the Earth revolved around the Sun.

See also

• Gamma Draconis in fiction

References