Monocerosstraddles the celestial equator between Orion and Canis Minor. Introduced in the early 17th century by the Dutchman Petrus Plancius, it represents the mythical unicorn. Its brightest star is Alpha Monocerotis, magnitude 3.9. Monoceros is ofter overlooked in favor of its glittering neighboring constellations, but it lies in the Milky Way and contains much of interest for owners of any size of instrument.
Depiction: The Unicorn
Highest in the Sky: January to February
Size Ranking: 35th
Coverage Area: 482 Sq. Degrees
Right Acension: 7 hours
Visibility: 75°N to 80°S
M50: Open cluster
NGC 2232: Open cluster
NGC 2237: Rosette Nebula
NGC 2244: Rosette Nebula
NGC 2264: Christmas Tree Nebula
NGC 2346: Planetary Nebula
Plaskett's Star: Binary star
Best Viewed Objects/Stars
A triple star, divisible with a small telescope. The three stars, magnitudes 4.6, 5.0 and 5.4, form an arc.
8 Monocerotis (Epsilon Monocerotis)
A double star with components of magnitudes 4.4 and 6.7 that are easy to divide through a small telescope.
S Monocerotis (15 Monocerotis)
A highly luminous blue-white star, magnitude 4.7 (but slightly variable), in the cluster NGC 2264. It has a companion of 8th-magnitude, visible with a small telescope.
An open cluster about half the apparent size of the full Moon and visible with binoculars. A small telescope reveals its individual stars of 8th magnitude and fainter. It lies 3,000 light-years away.
A scattered open cluster. The same apparent size as the full Moon, it is just visible to the naked eye. Its brightest star is 5th-magnitude 10 Monocerotis, and several other individual member stars are visible with binoculars. It lies 1,200 light-years away.
An open cluster at the heart of the much larger Rosette Nebula. The cluster is easily visible through binoculars as an elongated group about two-thirds the apparent size of the full moon. However, excellent skies are needed to trace the outline of the surrounding Rosette Nebula, which is three to four times larger and shows up well only on photographs. The cluster and nebula lie about 5,000 light-years away.
An open cluster. It is visible with binoculars; when viewed through a small telescope it appears triangular in shape. Its brightest member is S Monocerotis. Long-exposure photographs show a surrounding of faint nebulosity, which includes a dark lane known as the Cone Nebula. The cluster and associated nebula are about 2,500 light-years away.