Orion is a winter warrior

Winter is a great time to find the constellation Orion in the east soon after sunset.

Draw a line through his three belt stars back toward the horizon. They point you to Sirius, the brightest star visible in the night sky. Watch the star for a few minutes and you will observe that it sparkles with different colors. This is caused by the light being bent and refracted as it goes through the thick atmosphere.

When you look at a star near the horizon, its light is going though five times as much atmosphere as a star directly overhead.

To the right of Orion's belt are the three stars that make up his sword. The central point of light in the sword is not a star at all but a stellar nursery called the Orion Nebula, which is a glowing cloud of gas. With binoculars you can see several of the hot, young, blue stars at the heart of the nebula. These stars are less than a million years old. They give off a great deal of ultraviolet light that excites the molecules in the gas cloud and causes it to glow.

Also, winter is a great time to investigate a local astronomy club. Besides the Seattle Astronomical Society, there are clubs in Everett, Bainbridge, Tacoma and Bellevue. You can find links to the various clubs at SAS' Web site, www.seattleastro.org. All clubs welcome interested individuals to attend a meeting, and if you decide to join, membership fees are low.

— Rodney Ash, Special to The Seattle Times

Rodney Ash is a member of Seattle Astronomical Society, www.seattleastro.org. Star Watch appears in NWWeekend the first Thursday of each month.