“Well, now that we have seen each other,” said the Unicorn, “if you’ll believe in me, I’ll believe in you. Is that a bargain?”
“Yes, if you like,” said Alice.

Through the Looking-Glass
by Lewis Carroll
Monoceros, the Constellation
is unique, as is its namesake, the Unicorn. Both are figments of the imagination; and they are about equally hard to find. But if you will look with sharp eyes into the winter sky and draw in your mind a triangle with Betelgeuse, Procyon, and Sirius as the vertex stars, you will find within that triangle a few stars of fifth magnitude. These, and a couple of others south and east of Procyon, were configured by Jacob Bartsch in 1624 to give this lonely part of the heavens a name. Bartsch was a assistant to Johannes Kepler; later, he became Kepler’s son-in-law.

As you look toward these stars you are looking diametrically opposite to the direction of our galaxy’s center. This is the reason for the paucity of stars. There are, though, a number of very interesting celestial objects for study. Foremost, perhaps, is the Rosette Nebula, although its exceptional beauty is best appreciated with photographic exposures through large telescopes. A central cluster of young stars is surrounded by a gas cloud of hot, ionized hydrogen, which in turn is enclosed by a shell of cold hydrogen. The star cluster itself (not the nebula) was discovered by the first Astronomer Royal, John Flamsteed.

This image of the Rosette Nebula was taken by University of Michigan Professor Patrick Seitzer with the Schmidt telescope in Chile. [http://www.astro.lsa.umich.edu/]
Two full moons would fit side to side within the borders of the picture. The nebula itself has a diameter of 90 light years. Inside the nebula lies an open cluster of bright young stars designated NGC 2244. These stars recently formed from the nebular material. Ultraviolet light from the hot cluster stars causes the surrounding nebula to glow.
Both cluster and nebula are visible in the Spring constellation of Monoceros, the Unicorn. The star cluster can be glimpsed with one's dark adapted eye under good observing conditions, and is easily picked out with binoculars. A medium sized telescope is needed for a good view of the nebula.

M50, a nice object for a small telescope, is an open cluster with a red star in the field. The group lies just less than half way from Sirius toward Procyon, midway—east to west—between Alpha and Beta Monocerotis. It consists of from 50 to 100 stars within an area of about 10 arcminutes diameter. On a very good night these stars can even be seen with the unaided eye.

There are a number of interesting multiple star systems in the constellation, including Beta Monocerotis. Another is the pretty blue-and-gold double, Epsilon Monocerotis, which lies 10° north of Beta.

There are a couple of variable objects in Monoceros, as well. T Monocerotis, 2° northwest of Epsilon, is a Cepheid variable with a period of 27 days and a magnitude range of 6.4 to 8.0. And R Monocerotis is the variable star associated with the peculiar Hubble’s Variable Nebula. This is a comet-shaped reflection nebula whose brightness fluctuates without discernible rhythm, and without a link to the visual magnitude of R-Mon. It has been suggested that the wavering luminosity of the nebula comes from a bipolar emission of energetic gas ejected from the star. Some observers judge R Monocerotis to be not a star, but a protoplanetary system, a tightly condensed nebulous region where another “solar system” is being formed. Hubble’s Variable Nebula actually had been discovered by William Herschel, but it was Hubble who found, from photographs taken at several observatories, that the nebula varied in shape and brightness. The object, listed as NGC 2261, has the further distinction of being the first object photographed by the 200-inch Hale telescope at Mount Palomar in 1948.

Also in Monoceros is the interesting Plaskett’s Star, one of the most massive binary systems known. Situated about 50 million miles apart—about half the Earth-Sun distance—are two giant stars. Their total mass is believed to be a hundred times the mass of the Sun. In contrast, there is also a pair of red dwarf stars in Monoceros, Ross 614. The primary has a mass just one seventh that of the Sun; and the secondary only half of that.

Unicorns are elusive, and there are many different stories about them, some enchanting, some just strange. In fact, unicorns have a very definite presence in lore of all kinds, and in art, poetry and literature. The San Francisco Museums of Fine Art have an etching by the renowned artist Albrecht Dürer (1471-1528) showing The Abduction of Proserpine on a Unicorn. In the coat of arms of the United Kingdom, a unicorn is proudly shown, together with a lion, in support of the crown. Lions and unicorns are traditional rivals, and they are equally capable of victory one over the other. And let it be known that a unicorn is not simply a horse with a horn. A unicorn has cloven hooves like a deer, a beard like a goat, and a long tail like a lion’s. Unicorns are symbols of the mystical, the alluring and delightful; and that is precisely because they are not literally real.

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