Mizar is the middle star of the Plough’s handle, with Alcor beside it a naked-eye pair, and in a telescope a system of several stars bound together.
At a glance
| type | white star (class A) |
|---|---|
| distance from the Sun | 85.8 light-years (26.3 pc) |
| its light left it | 85.8 years ago |
| luminosity | 33 × the Sun |
| radius | 2.4 × the Sun |
| surface temperature | 9,000 K |
| constellation | Ursa Major (Great Bear) |
Read off the piece’s own catalogue, the same values it draws with.
About Mizar
Mizar is a white star of class A, wider and hotter than the Sun. Keen eyes see faint Alcor close beside it, a pair long used as a test of eyesight. A small telescope splits Mizar itself into two stars, and it was one of the first double stars ever seen through a telescope.
Each of those two stars is itself a close pair, revealed only by the regular splitting and shifting of lines in their spectra; the brighter one was the first such spectroscopic binary ever discovered. Alcor is a pair too, so the patch of light the eye sees as two stars holds six.
Mizar and Alcor belong to the Ursa Major moving group, travelling through space with most of the other stars of the Plough.
What you see in the piece
Fly to Mizar and the pair resolves in front of you: Mizar Ab, Mizar Ba and Mizar Bb close together, Alcor and its companion further off, each drawn at its real brightness.
Measured or modelled
Whether Alcor is truly bound to Mizar or simply travelling alongside it has long been debated; current measurements favour a loose bond.
Questions
Are Mizar and Alcor a real pair?
Yes, they lie at nearly the same distance and move together; together they form a system of six stars.
How far away is Mizar?
Mizar is 85.8 light-years (26.3 pc) from the Sun.