Mizar
ILLUSTRATION FROM SPECTRAL TYPE A2V · 9110 K · 77.3 L☉ · VARIABLE, MAG 2.20–2.34 · TIMING NOT TO SCALE
OVERVIEW
] STARMizar is an A2V white main-sequence star in the constellation Ursa Major, 85.81 from Earth, shining at apparent magnitude 2.23 (). It is catalogued as 79 ζ UMa, GJ 3783A and HD 116656, among 7 designations in total.
- WHAT IT IS
- White main-sequence star
- HOW FAR
- 85.81
- HOW BRIGHT (V)
The light arriving now left it that long ago.
Bright enough for the naked eye, under a sky dark enough.
THE MODEL
] RADIUS FROM THE LUMINOSITY AND THE TEMPERATURECALCULATED · NOT AN OBSERVATION · RADIUS FROM THE LUMINOSITY AND THE TEMPERATURE · SPECTRAL TYPE A2V · 9110 K · 77.3 L☉ · VARIABLE, MAG 2.20–2.34
Drawn from the radius from the luminosity and the temperature and from the same properties the picture at the top of this page uses, at the distance a flight to it would stop. Drag it, or use the arrow keys, to look from another direction. The stars behind are the 498,631 this catalogue holds real distances for, at their real positions and drawn from where the camera actually is — so the constellations are wrong, and that is the point. This is the sky from there, not the sky from here.
OBSERVING
] FROM WHERE YOU AREWhat it takes to see Mizar for yourself. Everything in this part of the page is worked out for a real horizon, a real night and the equipment you say you have.
Say where you are, and this line says when Mizar is worth going out for.
THROUGH AN EYEPIECE
] 150 MM TELESCOPE · 25 MM EYEPIECEBright enough to pick out with your eyes alone, and from a lit street as well as a dark one. Its brightest companion sits 14.4″ away, which at 48× is cleanly split.
- 48×
- 1.08
- 1.25
- 13.0
- · AB
- 14.4 · cleanly split
- · AC
- 11.9 · cleanly split
- · AD
- 8.3 · cleanly split
- APPARENT MAGNITUDE ()
- 2.23 · within reach
A is where the pair was the year it was measured — the ones above, between 2020 and 2022, and a pair in a real orbit has moved since.
APPARENT PLACE
] EQUINOX J2026.7Where a telescope has to be pointed today, which is not quite where the catalogue records the object: the coordinate grid itself has turned since the year 2000 the catalogue is referred to.
- RIGHT ASCENSION
- DECLINATION
- GRID TURNED SINCE
- 12.6
- PROPER MOTION SINCE
- 3.28
Computed for 2026-08-27 00:00 UT. Two things separate it from the catalogued position above: Mizar has moved under its own proper motion, and the coordinate grid has turned under it — about fifty arcseconds a year of precession since 2000, and the small nodding of the Earth’s axis on top of that. Aberration and refraction are not included, and neither is parallax; each is under an arcminute, which is also about as well as the catalogued position is known. The same figure for any date.
DOUBLE STAR
] 3 PAIRS| COMPONENTS | SEPARATION | POSITION ANGLE | MAGNITUDE | MEASURED |
|---|---|---|---|---|
| AB | 14.4″ | 153° | 3.88 | 2022 |
| AD | 498.1″ | 103° | 7.62 | 2020 |
| AC | 715.5″ | 73° | 4.01 | 2020 |
Separation and position angle are as measured in the year given; a position angle is measured from north, through east. Washington Double Star Catalog 13239+5456.
CATALOG DATA
] 12 FIELDSThe raw catalogue values, as the source published them, with the error bars where one was published — sorted by what each set of figures is about rather than by the order they happened to be stored in.
WHAT IT IS MADE OF
What the object is in itself, rather than how it happens to look from here.
- Spectral type
- Luminosity
- 77.3393
HOW BRIGHT IT IS
What the light adds up to, measured through one filter at a time. A magnitude is a brightness on a backwards scale — the smaller the number, the brighter the object.
- Colour index (B−V)
- Variable magnitude, brightest
- Variable magnitude, faintest
WHERE IT IS AND HOW IT MOVES
Position, motion across the sky and the size it covers on it. These are measurements of the object as seen from here, so every one of them depends on where here is.
- Proper motion (RA)
- 121.23
- Proper motion (Dec)
- −22.01
- Radial velocity
- −5.6
OTHER NAMES AND NUMBERS
The identifiers other catalogues file this object under, for anyone joining this data to theirs.
- Also known as
- Zeta Ursae Majoris
- Washington Double Star id
- 13239+5456
- Wikidata item
- Q66477109
- Wikipedia article
- Mizar
ALSO KNOWN AS
] 7 DESIGNATIONS- Bayer/Flamsteed 79 ζ UMa
- Common name Mizar
- Gliese GJ 3783A
- HD HD 116656
- HIP HIP 65378
- HR HR 5054
- IRAS IRAS 13219+5511
LOOK IT UP ELSEWHERE
] 3 SERVICESEach link carries the identifier printed beside it. Nothing on this page is a measurement of our own, so a number that disagrees with one of these is worth reporting — and a service that has never catalogued this object under this name will say so plainly.
- SIMBADHR 5054
Cross-identifications, measured values and the reference behind each of them.
- ADSobject:"HR 5054"
Papers indexed against this object rather than against the string, newest first.
- VizieR5″ around 200.9812 +54.9254
Every published table with a row at this position, searched by coordinates rather than by name.
CITE THIS PAGE
] DR1This page is live and its numbers move when an upstream refreshes, so the citation names the release the rows belong to rather than the day you read them. The release itself is frozen, republished as a bundle, and is what a data-availability statement should point at.
SpaceCatalog. Mizar [catalogue entry]. Data release DR1 (2026-08-21). https://spacecatalog.org/object/mizar
@misc{spacecatalog_mizar,
author = {{SpaceCatalog}},
title = {{Mizar}},
howpublished = {SpaceCatalog, data release DR1 (2026-08-21)},
year = {2026},
url = {https://spacecatalog.org/object/mizar},
note = {Catalogue entry, data release DR1 (2026-08-21). Values from HYG Database v4.1.}
}The values above were taken from HYG Database v4.1 — CC-BY-SA-4.0. Citing this page does not replace citing that catalogue, and its licence is share-alike: the terms reach whatever you build from these rows.