Cold, clear winter nights usually provide the best conditions for star gazing and last night was no exception. At 9 PM, Orion, perhaps the most well-known winter constellation, was high in the southern sky and Sirius, the brightest star in the sky, shimmered to its southeast.
Orion, which resembled a hunter to ancient civilizations, is easily recognized as a prominant rectangle (shoulders and feet), bisected by a three-star belt; a less-obvious sword hangs below the belt. The left (east) shoulder is Betelgeuse, a red super giant that is 900 times the diameter of our sun. Orion's right (west) foot is Rigel, a blue-white super giant that is the 7th brightest star in the sky. If you look closely, you will see a fuzzy area near the midpoint of Orion's sword; this is the Orion nebula, a star nursery. Of course, the association of these stars is purely a human interpretation; the component stars vary dramatically in their distance from the earth and the four corners of Orion are further from each other than they are from us.
When we look at the night sky we are looking back in time. Sirius is 8.7 light years from earth; in other words, light, traveling at 186,000 miles per second, takes 8.7 years to travel from Sirius to earth and we see that star as it existed 8.7 years ago. Betelgeuse is 427 light years away and Rigel is 773 light years away; we see them as they existed in 1580 AD and 1234 AD, respectively. The Orion nebula is 1500 light years away; the light that we see left the nebula when Polynesians were first colonizing Hawaii!
