[Turn on star projector and all planets. Turn on direction indicators. Begin to fade to darkness.]
Let's pretend that it's about 9:00 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 (June 6, 2000), the most prominent stars in the sky make up the constellations of Ursa Major, Bootes, Virgo, Lyra and Aquila. While our eyes adapt to the darkness, let's point out a few constellations in the late spring sky. [Point out Ursa Major, Bootes and Arcturus, Virgo and Spica, Leo and Regulus, and the crescent moon] Finally, just above the horizon in the west in the constellation Gemini is the planet Mercury. Mercury is at its greatest elongation of the year right now and is 23o from the Sun. Let's now move things along to what the sky looks like around midnight. [Point out Lyra, Aquila and Altair, Cygnus and Deneb, Summer Triangle]
[Display low Earth orbiting satellite.] Now, let's explore the topic of our interest in more detail. Since the speed of light is finite, it takes time for the light emitted by a star to reach us. In fact, it takes 8 minutes for the light from our Sun to reach us. The Alpha Centauri system is the nearest star system to the Sun and it requires over 4 years for the light from Alpha Centauri to reach us. The bright stars in our simulated sky are all much farther away:
[Point out Cygnus] In this area of the sky, is an object called Cygnus X-1. Through a telescope, it appears as a magnitude 9 blue star (meaning that it is not visible to the naked eye). However, it is of special interest because it is an emitter of X-rays. It lies at a distance of about 14,000 lightyears from Earth. It is of special interest to us since it is thought to be a binary system with one of its components a 10 solar mass black hole. [Point out galactic center] About twice as far away, is the center of our own Milky Way galaxy in this area of the sky. In fact, this is the brightest part of a faint band of light stretching across the summer sky. This is the view of the disk-shaped Milky Way galaxy as seen from inside. About 30,000 lightyears from us in the direction of the constellation Sagittarius in the center of the Milky Way is a two million solar mass black hole. [Turn on Projector] [Point our 3C-273] Much farther still, in the direction of the constellation Virgo lies a quasi-stellar radio source (or QUASAR for short) called 3C-273. This quasar is over 2 billion lightyears from us. It is thought to be home to a black hole with a mass of 1.5x1013 times that of the Sun (that is, a mass of 15 trillion solar masses).
Let's now begin the multimedia part of the show and explore in depth the properties of light, motion and these so-called "black holes."
Go to next section.