The unicorn

¡SkyCaramba! Weekly astronomy blog for the week ending February 23, 2013 

One of the modern constellations named just a few hundred years ago is named for a legendary animal that has been the subject of stories for a few thousand years. We can’t explain why such a fabled creature wasn’t given a place in the sky until 1624. But we can still enjoy the constellation on the meridian around 9pm in the middle of February.

Monoceros is the Latinized name for the unicorn. It simply means one-horned. Just what the rest of the animal looked like is up to the imagination. The front end is usually depicted as a horse. The back is sometimes another animal such as a lion. Some historians think the unicorns described in ancient writings were actually rhinoceroses. Imagine someone from the Mediterranean region where such animals were unknown saying the most intriguing things about what he saw on his trip to India.

German scientist Jakob Bartsch named the constellation Unicornu almost 400 years ago. Some astronomy history experts give credit for this constellation to Dutch astronomer Petrus Plancius because he is the one who named it Monoceros at about the same time. The two names mean essentially the same thing.

The stars of Monoceros are dim, so they are unnamed. But it’s still fun to look at them in a telescope. Beta Monocerotis is revealed to actually be three stars! They are about 700 light years away.

Several of the stars in Monoceros are double stars. There is also a variable called T Monocerotis. Its brightness varies over the course of 27 days and repeats. You will also find many nebulae in Monoceros. They are thought to be remnants of old stars that have collapsed. The remnants glow not so much because of visible light reflecting off of them but because of some starlight wavelengths stimulating them to glow. One such nebular is named Hubble’s Variable Nebula. Edwin Hubble compared photographs of it and discovered it to change brightness unpredictably.

You’ll find the celestial unicorn just east of Orion and just north of Canis Major.