Spotting the Celestial Unicorn

It’s tough to know where constellation stories and names originate. Often their roots are lost in antiquity, but we think that Monoceros may have a more modern origin. Some believe that it might have been the 16th-century Dutch theologian, cartographer and astronomer Petrus Plancius who invented this constellation, though some think it might have been named “Unicornu” by German astronomer Jacob Bartsch who published Plancius’ star maps in 1624.

If you can identify Monoceros in a dark moonless sky (which is pretty much the only way it’s possible), you should also be able to see the faint wintertime Milky Way flowing gently southward through it.

Once you find Monoceros, you’ll discover it takes quite an imagination to fashion a unicorn from its stars. But it’s not so much the constellation that’s interesting as what’s lurking within. Though they’re rather faint, quite a few celestial wonders are visible if you have a small telescope to aim in this direction.

Monoceros is home to a beautiful triple star system -- three stars that orbit a common center of gravity -known as Beta Monocerotis. It was the famous astronomer William Herschel who discovered it in 1781, the same year he found the planet Uranus. Herschel found the three stars of Beta Mon to form a triangle that, from our distance of about 700 light years, appears not to change over time, and he described it as one of the best triple star systems he’d ever seen.

Also lying within the boundaries of Monoceros is the famous interstellar cloud named the Rosette Nebula that engulfs a star cluster known as NGC 2244. With a backyard telescope, one can sometimes make out some diffuse neb-