) is a faint constellation
in the winter
night sky, surrounded by Orion
to the west, Gemini
to the north, Canis Major
to the south and Hydra
to the east. Other bordering constellations include Canis Minor
Monoceros is a constellation that is not very easily seen with the naked eye, with only a few fourth magnitude stars. Alpha Monocerotis
has a visual magnitude
of 3.93, slightly brighter than Gamma Monocerotis
, which has a visual magnitude of 3.98.
However, Monoceros does have some interesting features to observe with the aid of a small telescope. Beta Monocerotis is an impressive triple star system, the three stars form a triangle which seems to be fixed. The visual magnitudes of the stars are 4.7, 5.2 and 6.1. William Herschel discovered it in 1781 and commented that it is 'one of the most beautiful sights in the heavens'.
Epsilon Monocerotis is a fixed binary, with visual magnitudes of 4.5 and 6.5.
S Monocerotis, or 15 Monocerotis, is a bluish white variable star and is located at the center of NGC 2264. However the variation of its magnitude is not too great. It has a companion star of visual magnitude 8.
V838 Monocerotis had an outburst starting on January 6, 2002.
Monoceros also contains Plaskett's Star, which is a massive binary system whose combined mass is estimated to be that of almost 100 Suns put together.
Notable deep sky objects
Monoceros contains many clusters and nebulae, most notable among them;
Monoceros is a relatively modern constellation. Its first certain appearance is on the globe by the Dutch cartographer Petrus Plancius
, and was later charted by Jakob Bartsch
as Unicornus in his star chart of 1624
. Heinrich Wilhelm Olbers
and Ludwig Ideler
indicate the constellation may be older, quoting an astrological work from 1564
that mentioned "the second horse between the Twins
and the Crab
has many stars, but not very bright"; these may ultimately be due to Michael Scot
of the 13th century
, but refer to a horse and not a unicorn, and its position does not quite match. Joseph Scaliger
is reported to have found it on an ancient Persian
- Ridpath, Ian; Wil Tirion (2007). Stars and Planets Guide. London: Collins.