[Turn on star projector and all planets. Turn on direction indicators. Begin to fade to darkness.]
Let's pretend that it's about 6:00 or 6:30 in the evening. The sky begins to darken and we see the first few stars become visible. Notice the red letters which indicate compass directions.
At this time of year, the most prominent stars in the sky make up the constellations of Orion, Cassiopea, and Auriga. While our eyes adapt to the darkness, let's point out a few constellations in the winter sky.
[Point out Orion, Betelgeuse, Cassiopea, Cetus, Mira, Auriga, Capella.]
There are a few other conspicuous lights here in our simulated sky. The bright object in the western sky is actually the Sun, so this perspective is very artificial. It reflects what the sky would look like this time of year at about 6:00 if we could see the stars while the Sun was still up. Let's remove the Sun and see what else we have. Three of the brightest "stars" in the sky are in fact not stars at all, but are planets. Tonight (February 18, 1999) there are five solar system objects visible in the western sky. The one closest to the horizon is Mercury. Because of its closeness to the Sun, even though it is quite bright, Mercury is difficult to see in the twilight glow. A much easier to see and brighter object is Venus. You may have seen it as the bright "evening star" this evening, although it will have set by the end of the show tonight. About 2o or 3o from Venus is Jupiter. The gap between these two planets will close to a minimum of 1/4o on the night of Tuesday, February 23. For comparison, the moon is 1/2o in diameter. About 30o from Jupiter is Saturn. About 2o or 3o from Jupiter we find the crescent moon. This month is rather interesting in that there is no full moon. But tonight we want to explore much deeper into space than just the solar system.
Astronomers use the speed of light to measure distances. The light we see from the Sun is 8 minutes old, reflecting the fact that it has travelled the 93,000,000 miles from the Sun to us at the impressive speed of 186,000 miles per second! The light reflected from the moon is only about a second old. The light reflected from Mercury is about 9 minutes old, light reflected from Venus is about 12 minutes old, the light reflected from Jupiter is about 45 minutes old, and the light reflected from Saturn is about 1 hour and 20 minutes old. The light from the stars we see tonight ranges from about 10 years to 500 years old. For example, Sirius is 8.7 light years away (a light year is equal to 6 trillion miles, so we will measure astronomical distances not in miles, but in light years). The bright star in Orion, Betelguese is 520 light years away. So the light we see from Betelguese started its journey at about the time Columbus sailed to the "new world." Let's now explore some of the nonstellar objects in the sky.
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