Eltanin is an orange giant and the brightest star of Draco, the star through which the aberration of starlight was first discovered.
At a glance
| type | orange giant (class K) |
|---|---|
| distance from the Sun | 154 light-years (47.3 pc) |
| its light left it | 154 years ago |
| luminosity | 496 × the Sun |
| radius | 42.1 × the Sun |
| surface temperature | 4,200 K |
| constellation | Draco (Dragon) |
Read off the piece’s own catalogue, the same values it draws with.
About Eltanin
Eltanin, Gamma Draconis, is an orange giant, a star that has swollen as it ages and cooled at its surface. Its name comes from the Arabic for the serpent or dragon, and it marks the Dragon’s head.
It passes almost directly overhead at the latitude of London, which made it ideal for an instrument pointed straight up. James Bradley, measuring it with such a telescope, found that its position shifted through the year in a way parallax could not explain: the aberration of light, caused by the Earth’s motion through space.
That discovery gave the first direct proof that the Earth moves around the Sun, and a new measure of the speed of light.
What you see in the piece
In the piece it is the brightest point of the Dragon’s head, warm orange, with Rastaban farther off behind it.
Questions
What is the brightest star in Draco?
Eltanin, Gamma Draconis, an orange giant 154 light-years (47.3 pc) from the Sun.
Why is Eltanin famous?
Observing it, James Bradley discovered the aberration of starlight, the small shift in star positions caused by the Earth’s motion around the Sun.