[Turn on star projector, all planets, Sun and Moon. Turn on direction indicators. Begin to fade to darkness.]
Let's pretend that it's about 7:00 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 (October 19, 2000), the most prominent stars in the sky make up the constellations of Ursa Major, Lyra, Cygnus and Aquila. While our eyes adapt to the darkness, let's point out a few objects in this Fall's sky. This large object in the western sky is in fact the sun! Therefore this view is rather artificial and represents what the sky would look like around 6:00 if we could see the stars while the sun is up. Bright in the southwestern sky tonight is the planet Venus. It is near the constellations of Scorpio and Sagittarius. Also, the planet Mercury is above the horizon at sunset, but is very hard to see because of the glare of twilight. [Point out Milky Way, Ursa Major, Arcturus, Spica and Virgo] In fact, in the direction of the constellation Virgo lies a cluster of galaxies called the Virgo Cluster which is 50 to 70 million light years away. This means that the light we see when we observe these objects left their source when dinosaurs still roamed the Earth! Also in the constellation Virgo is a quasar 3C-273 which is 2 billion light years away. I wonder what the Earth was like 2 billion years ago?
Let's let the Earth revolve around and point out some more objects that appear latter at night. [Point out Lyra, Cygnus, Aquila (summer triangle).]
Around midnight, we see the Hyades Cluster and the Pleiades Cluster rise in the east. Near these clusters are the planets Jupiter and Saturn. Also, this evening the third quarter moon is in this area of the sky near the constellation of Orion the Hunter.
As we have mentioned, the finite speed of light implies that by looking out at the night sky, we are actually looking back into time. The light from the Moon is about 1 second old, the light from the Sun is 8 minutes old, the light from Vega is about 25 years old, the light from the center of our galaxy is 30,000 years old, the light from the galaxies of the Virgo cluster is 50 to 70 million years old, and the light from some quasars is several billion years old.
Therefore, we can, in a sense, use the night sky as a "time machine." The farther away we look in space, the farther back in time we see. Unfortunately, to see further back in time, we have to look far away. If we want to see what things were like around here in the past, then we have to be more creative. In the area of paleontology, people have learned a great deal about what things were like in the past on the Earth. In particular, impressive creatures called dinosaurs once lived on our planet. Let's now start the multimedia part of the show and explore dinosaurs in much more detail.
Go to the next section.