Star Points for January, 2003; by Curtis Roelle Best Time for Viewing Saturn It's hard to believe that we are starting the third year of the third millennium already. Over the past year I logged at least 50 observing sessions in my journal. Not too bad considering there were two months spent away from observing due to a broken ankle. The observations were made at various times. In the evening after sunset, up in the dead of night, or the hours prior to morning twilight. There were some all nighters, several "star parties" to boot, and daytime sessions for solar observing. Some opportunities were used for gathering scientifically useful data but most were spent observing the heavenly sights for the sheer joy of just seeing what's out there above and beyond the back yard. If you're still contemplating resolutions for the new year, I have a suggestion. How about endeavoring to get outside - away from the city lights even - and under the stars more often? A good opportunity is coming up which may help you get started. At the Bear Branch Nature Center on Saturday, January 11 you may visit the planetarium for a show and then observe the stars, weather permitting, until midnight through telescopes provided by the members of the Westminster Astronomical Society. For planetarium reservations you'll need to call the nature center at 410-876-9234. The star party is free and starts at 8 p.m. EST. If you have a telescope you should take a look at Saturn now. It doesn't matter how big of a telescope you have, or if it's brand new with North Pole frost still glistening on its tube, or if it came in Santa's pack a many trips ago. Saturn has something for every telescope. First there are the rings. The rings surrounding the planet's ball is visible in the smallest of telescopes. Even in binoculars the planet has the shape of a football due to the oval shape (eccentricity) of the rings. With a small telescope you should easily be able to see the dark gap between the rings and the round planet itself. With a medium sized telescope you can see the shadow of the planet being cast onto the rings passing behind it by the sun. You should also be able to see Saturn's brightest moon, Titan. Titan will look like a faint star, but probably the brightest star in your eyepiece's field. Larger telescopes will begin to show gaps between the rings themselves. The largest one is the Cassini division, an 1,800 mile wide gap discovered in 1675. The Encke division is smaller and as far as amateur instruments go, is primarily visible using premium optics only. A number of moons of Saturn are visible. The brightest ones are Titan, Tethys, Dione, Rhea, Iapetus, Enceladus, and Mimas. These moons revolve around the planet in orbits that last from just under one to 79 1/3 earth days. Identifying the individual moons can be tricky. However, finder charts are available. Sky and Telescope magazine has finder charts for both Jupiter's and Saturn's moons and is available on news stands. Sky and telescope's web site also has loads of useful information on other planetary phenomena at http://skyandtelescope.com/observing/objects/planets/. Currently, Saturn is making a fine appearance. To the unaided eye it appears as a bright yellow "star" high above the constellation Orion the Hunter. It can be found nearly overhead between 10 and 11 p.m. EST. On Saturday night, January 4-5, Saturn slowly glided past the "Crab Nebula" a faint cloud of gas in the Milky Way. In the year 1054 A.D. Chinese astronomers recorded a bright "new star" which suddenly appeared in the modern constellation of Taurus. Then in 1731 an amateur astronomer discovered a glowing cloud of gas. It was later deduced that the "star" observed by the Chinese was actually a supernova, or exploding star, and the nebula was the glowing slaughtered remains of the star. The nebula was nicknamed the Crab Nebula because of its leg-like tendrils of gas visible in photographs. The dazzling light of Saturn swamps the crab because the planet is 250,000 times brighter than the nebula according to Sky & Telescope's Fred Schaaf. But the two are drifting apart and starting tonight you'll have a higher chance of seeing them both in the same eyepiece as they separate. The Crab Nebula is estimated to be located between 6,000 and 7,000 light-years from the Earth, so let's split the difference and say 6,500. Because light travels at a finite speed it required 6,500 years for the supernova's flash to reach earth after the star exploded. Therefore, the supernova observed by the Chinese astronomers in 1054 A.D. may have actually exploded around 5500 B.C.! The star would have remained visible in telescopes (had there been any) for 6,500 years after the star's destruction until the expanding shell of light thrown off by the explosion finally reached earth. Even tonight when you go out and look at the Crab Nebula you are looking at light which left the nebula on its journey to your eye around 4500 B.C. Light takes 72 minutes to reach earth from Saturn, at opposition. Therefore Saturn is 72 light minutes away. If you could drive 75 miles an hour 24 hours a day it would take over 1,200 years to reach Saturn. The bottom line is that the nebula is about 48 million times farther from earth than Saturn is. So think about that should you get the chance to see both objects in the same eyepiece field.