IAU Constellation (UMi) · Genitive: Ursae Minoris · Northern Sky

Ursa Minor Constellation & North Star Guide

Ursa Minor IAU constellation guide: Little Dipper asterism, North Celestial Pole navigation, Polaris (Alpha Ursae Minoris), and limiting-magnitude stars.

Solid-Angle Area256 sq deg (Rank #56 of 88)
Best Evening MonthJune
Visibility Latitudes+90° to −10°
Brightest StarPolaris (Alpha Ursae Minoris) (+1.98)

Sky Navigation & Astrophysical Context

Ursa Minor encompasses 256 square degrees around the North Celestial Pole, making it circumpolar throughout the year for virtually the entire northern hemisphere. Its seven main stars form the Little Dipper, whose handle tip is Polaris (Alpha Ursae Minoris, V ≈ +1.98), situated just 44 arcminutes from the true spin axis of Earth.

While Polaris and the two outer bowl stars—Kochab (Beta UMi, V = +2.08) and Pherkad (Gamma UMi, V = +3.05), known as the 'Guardians of the Pole'—shine brightly even through suburban light pollution, the four intermediate stars of the Little Dipper span magnitudes +4.2 to +5.0.

Consequently, visual observers routinely use the seven stars of the Little Dipper as a calibrated naked-eye limiting-magnitude and Bortle-scale sky-quality gauge before starting deep-sky observing sessions.

Bordering IAU Constellations: Draco, Camelopardalis, Cepheus.

Equatorial Center Position & Transit Altitude

Ursa Minor is centered near Right Ascension 15h 00m 00s, Declination +75° 00′ 00″ (The Little Bear).

J2000 Equatorial Sky Position (Ursa Minor) +90° 0° −90° 24h 12h RA 0h Peak Meridian Altitude 55° 40°N Lat 0° 30°S Lat RA: 15h 00m 00s Dec: +75° 00′ 00″ Epoch: J2000.0 · 256 sq deg (Rank #56) First-party vector diagram derived from IAU / CDS SIMBAD / Gaia DR3 astrometry.

Practical Star-Hopping & Observing Tips

  • Follow the Pointer Stars Dubhe and Merak in Ursa Major 28° northward to land directly on Polaris.
  • Count how many of the four bowl stars of the Little Dipper (magnitudes +2.1, +3.0, +4.3, and +5.0) are visible to estimate your naked-eye limiting magnitude.
  • Use a 75 mm+ telescope at 100× on Polaris to spot its +9.1-magnitude F3 V physical companion Polaris B at 18.2 arcseconds.

Notable Celestial Objects in & Near Ursa Minor

Cataloged Stars and Deep-Sky Objects Associated with Ursa Minor
ObjectFamilyClassificationRA (J2000)Dec (J2000)Min. Instrument
Polaris (Alpha Ursae Minoris North Star)variable-starsClassical Cepheid supergiant variable in a triple star system02h 31m 49.09s+89° 15′ 50.8″Naked eye (50–60 mm telescope at 60×+ to split Polaris B)
Mizar & Alcor (Zeta Ursae Majoris System)multiple-starsSextuple A-type stellar system (first telescopic & first spectroscopic binary)13h 23m 55.54s+54° 55′ 31.3″Naked eye for Mizar–Alcor; any 40–60 mm telescope at 40× for Mizar A–B

Scientific Sources Cited