Orion is favorite of 88 official constellations

Of the 88 officially recognized constellations, Orion is my favorite. For one, it is so prominent; its bright stars gleaming against the blackness of the winter night sky. Secondly, Orion contains one of the most impressive of sights seen through a backyard telescope: the Orion Nebula or M42 as it is called in comet hunter Messier's list.

Robert Burnham, in his classic Celestial Handbook, writes, "The Great Nebula in Orion (is) generally considered the finest example of a diffuse nebula in the sky, and one of the most wonderfully beautiful objects in the heavens." He later added, "In a moderately large telescope its appearance is impressive beyond words...the great glowing irregular cloud, shining by the gleaming light of the diamond-like stars entangled in it, makes a marvelous spectacle which is unequaled anywhere else in the sky."

Whew, what else can I add. To the unaided eye the nebula appears as a fuzzy "star" in the middle of Orion's sword, just below his belt. Through binoculars it becomes larger and more diffuse. For all of you who received telescopes for Christmas, your instrument will show a glowing, greenish cloud that to some observes takes on the appearance of a bat.

In my 80 mm scope the nebula shows very well as do the two other stars in the sword, the one to the north showing its own bit of nebulocity. In the eight-inch scope the nebula grows to a beautiful, glowing thing, but in the 11-inch scope M42 fills the field of view with a pale, greenish glow that takes on a life of its own.

The nebula has been measured to be about 30 light years in diameter which is more than 20,000 times the size of our own solar system (from the Sun out to and beyond the Ort cloud -- a subject for a later column).

The glow comes from ultraviolet radiation produced by the Trapezium, a four-star star cluster in the heart of the nebula. The eye alone cannot perceive the marvelous colors of the nebula. These colors can only be seen in time-lapse photography. The Hubble Space Telescope has captured one of the best images of the Orion Nebula and can be seen at http://antwrp.gsfc.nasa.gov/apod/ap060119.html

As amazing as the Orion Nebula is, it is only a small part of the great Orion Molecular Cloud Complex. A vast area of gas and dust stretching from M42 up to and past Alnitak, the easternmost star in Orion's belt. The cloud spans hundreds of light years. A very nice photograph of the cloud can be found at:

http://antwrp.gsfc.nasa.gov/apod/ap061015.html

The Orion Nebula is not the only thing to be seen in the constellation. Since part of the Milky Way goes alongside the Hunter, there are numerous other nebula, star clusters, and double stars to be seen using a telescope or pair of binoculars.

Orion is a veritable playground for someone with the time and the equipment to conduct a search.

SKY WATCH: Last quarter Moon, Jan. 11. Saturn is making a nice appearance in the early evening sky. Look at about 9:30 p.m. local time almost due east, Leo will be up and visible below it. Remember, Leo is a spring constellation.

Next time, Orion, Part 3.