The Great Bear is the third largest constellation in the sky and home to the famous Plough asterism — one of the most recognised star patterns in the northern hemisphere. Circumpolar from the UK, it never sets below the horizon.
The Plough (called the Big Dipper in North America) is almost always visible from UK latitudes. The seven bright stars of the Plough form the most recognisable asterism in the northern sky and serve as a signpost to a dozen other constellations.
Sky finder diagram — Dubhe and Merak (the Pointer Stars) extend five times their separation to reach Polaris, the North Star. ★ = Alioth is the brightest star in Ursa Major despite not being designated α.
The Plough (or Big Dipper) is made up of seven stars arranged in a distinctive saucepan shape: four stars form the bowl and three form the curved handle. From the UK it is visible every clear night of the year — just look north and its height above the horizon varies by season, but it never fully sets.
Dubhe (α) and Merak (β) form the outer edge of the Plough's bowl. Draw an imaginary line from Merak through Dubhe and extend it by about five times the distance between them — you will arrive at Polaris, the North Star. This is the easiest way to find north in the night sky.
The curved handle of the Plough points to a useful guide: Arc to Arcturus, then speed on to Spica. Follow the arc of the handle southwards to reach the brilliant orange star Arcturus (brightest star in Boötes), and continuing in a straight line leads to blue-white Spica in Virgo.
Ursa Major is circumpolar from the UK — it never sets below the horizon. However, April is the optimum month for evening viewing, when the Plough is high overhead and the deep-sky galaxies M81 and M82 are best positioned. Spring and summer are the best times for binocular and telescope work on the galaxies.
Five of the seven Plough stars — Merak, Phecda, Megrez, Alioth, and Mizar — are genuine physical siblings. They are all approximately 80 light-years away, travelling through space in the same direction at the same speed, making them one of the nearest stellar moving groups to Earth. The other two, Dubhe and Alkaid, are unrelated background stars that just happen to appear in the same direction.
| Season | Evening Position | Observing Conditions |
|---|---|---|
| Winter (Jan–Feb) | Low in the NE, tilted with handle pointing down | Good — rising to prominence |
| Spring (Mar–May) | High overhead, nearly at zenith in April | Best — highest position, galaxies well-placed |
| Summer (Jun–Aug) | NW sky in the evening, descending | Good — galaxies accessible before midnight |
| Autumn (Sep–Nov) | Low in the north, bowl uppermost | Poorer — lower altitude, more atmospheric haze |
The seven stars of the Plough are among the most studied in the sky. Counterintuitively, the brightest is not the alpha star but epsilon — Alioth — reflecting historical naming conventions that predated photometric measurement.
The brightest star in Ursa Major, despite not being labelled alpha. Alioth is a chemically peculiar Am star with unusual abundances of chromium and rare-earth metals in its atmosphere. It is part of the Ursa Major Moving Group.
The tip of the Plough's handle and the easternmost bright star of Ursa Major. Alkaid — also known as Benetnash or Benetnasch — is a hot B-type main sequence star, notably NOT a member of the Ursa Major Moving Group and significantly further away than its neighbours.
The most northerly of the two Pointer Stars and the alpha star of the constellation. Dubhe is an orange giant and a spectroscopic binary. Like Alkaid, it is NOT part of the Ursa Major Moving Group — it is actually moving in the opposite direction to the other Plough stars.
One of the most famous double stars in the sky. Mizar was the first telescopic double star discovered (1617), and Alcor sits just 12 arcminutes away — a traditional test of eyesight in many cultures. Mizar itself is a quadruple system, making the Mizar-Alcor group a sextuple star system.
The southern of the two Pointer Stars, Merak is a white A-type main sequence star and a founding member of the Ursa Major Moving Group. Together with Dubhe, it forms the most useful celestial navigation pointer in the northern sky, directing observers to Polaris.
Phecda and Megrez form the inner pair of the Plough's bowl. Megrez at magnitude 3.31 is the faintest of the seven Plough stars — historically it was thought to have faded in brightness, though this is not confirmed. Both are core members of the Ursa Major Moving Group.
Ursa Major is one of the oldest named constellations, referenced by Homer, Aristotle, and virtually every culture in the northern hemisphere. The bear interpretation is remarkably consistent across unconnected civilisations — suggesting an origin predating the migration of modern humans into the Americas.
The most widespread Greek myth identifies Ursa Major with Callisto, daughter of the Arcadian king Lycaon. Callisto was a devoted huntress and follower of the goddess Artemis who took a vow of chastity. Zeus, however, disguised himself as Artemis to seduce or assault her — accounts vary — and she became pregnant with Arcas.
When her pregnancy was revealed during bathing, Artemis expelled Callisto from her band. Hera, furious at her husband's infidelity, transformed Callisto into a bear. Years later, her son Arcas was about to unknowingly kill the bear — his own mother — while hunting. To prevent this tragedy, Zeus transformed Arcas into the smaller bear (Ursa Minor or, in some versions, Boötes) and placed them both in the heavens.
Hera, still angry, persuaded the sea god Poseidon to forbid the bears from ever setting below the horizon — which is why both Ursa Major and Ursa Minor are circumpolar from northern latitudes and never sink beneath the sea.
The constellation's remarkable antiquity is evidenced by a curious linguistic coincidence: both European and Native American cultures independently identified these stars as a bear and described the three handle stars as hunters chasing it — suggesting the myth may be over 13,000 years old, dating from when the ancestors of Native Americans crossed into the New World.
Callisto, transformed into a bear by Zeus or Hera, placed among the stars with her son Arcas. Forbidden by Poseidon from ever resting below the sea — explaining its circumpolar nature.
The three handle stars are hunters pursuing the bowl stars (a bear). In autumn, when the bowl tilts, the bear is being killed — explaining the season's red leaves (blood on the trees).
Known as the Plough or Charles's Wain (Charles's wagon). "Wain" derives from the Anglo-Saxon word for wagon, and the pattern was associated with the legendary King Arthur in medieval tradition.
In Chinese astronomy the seven stars represent the Northern Dipper (北斗七星, Běidǒu Qīxīng), one of the most important asterisms. Associated with the god of longevity and fortune telling.
The seven stars are the Saptarishi (सप्तऋषि) — the Seven Sages of Hindu tradition, including Vasishtha (Mizar) and his wife Arundhati (Alcor), traditionally looked to in marriage ceremonies.
Ursa Major punches well above its weight in deep-sky targets. Because it lies far from the obscuring dust of the Milky Way's plane, it offers a clear window into deep space — particularly towards clusters of galaxies tens of millions of light-years away.
One of the finest galaxies in the entire sky for small telescopes. M81 shows beautiful, tightly wound spiral arms and a bright central bulge. Discovered by Johann Bode in 1774, it forms a stunning binocular pair with M82 — both fit in the same low-power eyepiece field. Located 10° NW of Dubhe.
The famous starburst companion to M81. Seen edge-on, M82 has a dramatic cigar shape and is laced with dark dust lanes. Gravitational interaction with M81 triggered an intense burst of star formation and drives a superwind blowing material thousands of light-years out of the galactic plane. A 100mm telescope reveals its mottled structure beautifully.
One of the largest planetary nebulae in the sky, ejected by a dying sun-like star about 6,000 years ago. The "Owl Nebula" name comes from two darker circular patches visible in larger telescopes that resemble an owl's eyes. Located just 2.3° SE of Merak, close to M108 which is visible in the same field.
A large, nearly face-on spiral galaxy at the tip of the Plough's handle — 5.5° NE of Alkaid. Despite a relatively bright magnitude, its low surface brightness makes it challenging in light-polluted skies. Under dark skies a 150mm telescope reveals its asymmetric spiral arms. Two Type Ia supernovae have been observed in M101 in modern times.
A beautiful edge-on galaxy seen almost exactly in profile, near the Owl Nebula M97. Together these two objects make a striking pair at low magnification. M108's mottled, dusty appearance is rewarding through a 150mm or larger telescope. It is the brightest member of its own small galaxy group.
Located just 40 arcminutes SE of Phecda, M109 is a barred spiral whose central bar gives it a distinctive shape in photographs. Low surface brightness makes visual observation challenging, but astrophotography reveals its structure. It is the brightest member of the Ursa Major Cluster (also called the M109 Group).
Ursa Major is the perfect starting point for any beginner. The Plough is almost always visible from the UK, and once found, it unlocks the entire northern sky. Here is a step-by-step plan for your first observing session.
Step outside on any clear night and look north. The seven stars of the Plough should be obvious — if it is spring, they will be high overhead; if it is autumn, look low on the northern horizon. Take a moment to trace the bowl and handle shape before moving to optical aids.
The middle star of the Plough's handle is Mizar. Look carefully and you should see a faint companion, Alcor, sitting very close to it. In ancient cultures this was a traditional eyesight test. Most people can split the pair in dark skies; binoculars make it trivially easy.
With binoculars, point toward Dubhe (top-right star of the bowl) and sweep about 10° northwest. You should see two fuzzy patches of light — M81 appearing as a brighter, more circular glow and M82 as a smaller, elongated smudge. They fit comfortably in the same binocular field.
Practise the most important navigation trick in amateur astronomy: place Merak at the bottom and Dubhe at the top of the bowl's outer edge, then continue that line approximately five times the star-to-star distance. Polaris will be waiting — a fairly modest star sitting almost motionless at the North Celestial Pole.
Follow the gentle arc of the Plough's handle outward and continue the curve southwards for about 30°. You will arrive at brilliant orange Arcturus in Boötes — one of the brightest stars in the sky. Continue the arc further and you reach blue-white Spica in Virgo. This spring sky tour connects Ursa Major to three different constellations.
All seven Plough stars visible. Mizar–Alcor double star visible in dark skies. Navigation to Polaris, Arcturus, Spica.
Easy split of Mizar–Alcor. M81 and M82 visible as fuzzy patches. Mizar shown as a close double star.
M81 and M82 in detail. M97 Owl Nebula. M108 edge-on galaxy. Mizar as a beautiful wide double at 50×.
With a 200mm or larger telescope and dark skies, Ursa Major reveals itself as one of the richest regions for galaxy hunting in the entire sky. The absence of obscuring Milky Way dust means thousands of background galaxies become accessible.
At 200mm+ the spiral structure of M81 becomes apparent at 100× magnification. M82 reveals dramatic dark dust lanes crossing its disc. Under very dark skies, hydrogen-alpha filaments extending from M82's core are visible in large apertures.
Near Phecda lies a concentration of fainter galaxies around M109. NGC 3953, NGC 3963, and a dozen more galaxies inhabit this field. A 250mm telescope can reveal 6–8 galaxies within a 2° area in the same eyepiece field — a mini galaxy group tour.
At 100× Mizar splits into a spectacular pair separated by 14 arcseconds — Mizar A (2.27) and Mizar B (3.96). Each is itself a spectroscopic binary, making Mizar a quadruple system. Alcor at 11.8′ separation adds a fifth visible companion, and Alcor itself is a binary.
M81/M82 make a classic two-panel mosaic or single-frame target. M101 rewards wide-field imaging to capture its large apparent size. The Integrated Flux Nebula (IFN) — extremely faint galactic cirrus visible in very long exposures — is particularly prominent around M81/M82.
The galaxies of Ursa Major are bright enough to attempt from suburban gardens, but their low surface brightness means light pollution is your enemy. Driving to a dark site — even Bortle 4 or better — transforms M81/M82 from faint smudges into showpiece objects with visible structure in a 150mm telescope.