What kind of star is Megrez?
Megrez, catalogued as Delta Ursae Majoris (δ UMa), appears in the official constellation Ursa Major. Its apparent visual magnitude is about 3.32, while its estimated distance is about 81 light-years. Astronomers classify the object as A3 V main-sequence star. These labels describe temperature, luminosity class or system components; they should not be read as a claim that every naked-eye point is a single isolated star.
Megrez is a main-sequence A star, hotter, whiter and more massive than the Sun. Its distance, age indicators and velocity place it in the Ursa Major Moving Group with four other central Dipper stars. Because the group is dispersed, its members are not confined to the familiar outline, and the seven Dipper stars are not all relatives. Megrez’s comparatively modest apparent brightness is not caused by exceptional distance; its intrinsic luminosity is lower than that of several other Dipper members. Searches for circumstellar material and companions use its proximity and well-constrained group age as useful context.
The coordinate pair RA 12h 15m 25.56s, Dec +57° 01′ 57.4″ fixes the object's direction on the celestial sphere for the J2000 reference epoch. Right ascension works like celestial longitude measured in hours, while declination works like latitude north or south of the celestial equator. Proper motion and improved measurements can refine catalogue positions, but these coordinates are sufficiently precise for a finder chart or planetarium search.
Megrez data at a glance
| Proper name | Megrez | Catalogue designation | Delta Ursae Majoris (δ UMa) |
|---|---|---|---|
| Constellation | Ursa Major | Apparent magnitude | about 3.32 |
| Spectral or system type | A3 V main-sequence star | Estimated distance | about 81 light-years |
| Right ascension (J2000) | 12h 15m 25.56s | Declination (J2000) | +57° 01′ 57.4″ |
Values are rounded for an observer-friendly overview. Consult the linked SIMBAD record for component-level identifiers, bibliography, measurement provenance and newer catalogue values.
The name Megrez
Megrez derives from Arabic al-maghriz, “the base” or “root” of the bear’s tail, matching its place where the Dipper’s handle joins the bowl.
The Arabic name locates the root of the Bear’s tail, precisely where later European drawings attach the Dipper’s handle. Bayer labelled it Delta Ursae Majoris. While navigational guides usually emphasize Dubhe and Merak, Megrez became informally useful as an observing test: if all seven principal Dipper stars are plainly visible, the sky is at least transparent enough to show a third-magnitude star. The IAU standardized the traditional spelling in 2016.
Modern professional catalogues retain identifiers such as the Bayer designation alongside a proper name. The International Astronomical Union standardizes which name belongs to which component—an important distinction for systems whose combined light looks like one star from Earth.
How to find Megrez
Megrez is the faintest of the Big Dipper’s seven main stars and therefore a useful naked-eye transparency test. Find the junction between bowl and handle. Under heavy urban light pollution it can disappear even while the other six remain obvious.
Circumpolar from much of the north; easiest in northern spring when the Big Dipper climbs high in the evening. Visibility on a particular night still depends on latitude, season, time, horizon obstructions, weather and local light pollution. Use the interactive atlas below to check the surrounding field before observing.
Observation checklist
- Find the single star connecting the Dipper’s bowl to its curved handle.
- Use it as a quick transparency check: haze and city glow erase Megrez before the brighter six.
- Compare its white colour with Dubhe’s warmer tint.
- Follow the handle outward from Megrez through Alioth and Mizar to Alkaid.
Interesting facts about Megrez
- Megrez is the faintest of the seven principal Big Dipper stars.
- It belongs to the Ursa Major Moving Group.
- Its name describes the root of the Great Bear’s tail.
- Megrez is still a core-hydrogen-burning main-sequence star.
- It lies at a distance similar to Merak, Phecda, Alioth and Mizar.
Continue from Megrez into the night sky
Use the Ursa Major constellation guide to place this star within its larger pattern. When you are ready to observe, compare dark-sky places, find a nearby observatory, or follow our practical guide to finding a star in the night sky. Symbolically registered names are kept separately in the searchable Star-Register catalogue.
Sources and further reading
Measurements are rounded for readability. Multiple systems, variable stars and distant supergiants can have component-specific or model-dependent values. Survey panels show photographic sky fields, not the physical surface of the star.