DIGITAL EFFECT: Sun Rise to Set Fade scene off and reset time to approximately one hour before sunrise on -1500/10/31 with cardinal points on before fading the scene back on. Audience may predict where along the horizon the Sun will rise. Also, if possible turn on a 2D trail for the Sun for tracking the Sun’s path in this section.
To see what marking an astronomical event means, let’s try to record an astronomical event ourselves: where the sun rose on today’s date [give the current date], about 3500 years ago.
Note: Even planetariums with precession settings cannot adjust for the small change in inclination of the Earth’s axis, which affects the position of sunrise and sunset. Thus we are taking artistic license here. In contrast to our simplified presentation in the planetarium, the computer programs used by Hawkins and other researchers must take into account many factors which affect observed rising and setting positions, including local terrain, atmospheric refraction, and the shift in inclination of the Earth’ axis. DIGITAL EFFECT: Go to Sunrise Slowly run diurnal motion forward past sunrise until the disk of the Sun is halfway above the horizon for marking by the audience. (Sunrise and sunset can also be defined with the disk standing tangent on the horizon, or tangent just below the horizon, but we will use halfway as the rise/set position for this program.)
Let’s mark the position of sunrise.
Demonstrate how to place a horizon marker at the sunrise position.
Now let’s predict where sunset happened on this same day, about 3500 years ago. First I’ll speed up the planetarium, as if the Earth were spinning faster.
DIGITAL EFFECT: Go to Noon Turn on diurnal and let the audience watch the sun rise to noon. Stop diurnal here so the audience may predict where the Sun will set.It’s about noon on this day, about 3500 years ago.
Have you decided where the Sun will set? Then take your pointer and go over and place it where you predict the Sun will set. Remember your pointer so you can tell how close your prediction is.
Point out wide range of guesses: due to our indoor life, we usually have a poor notion of sunset position. Many students will place their pointers exactly at West.
DIGITAL EFFECT: Go to Sunset Begin diurnal motion, continue to sunset (Sun halfway down). The audience may mark the sunset position. Congratulate the person coming closest. Have students retrieve their pointers, leaving only the two which mark the sunrise and sunset. DIGITAL EFFECT: Go to Evening Fast forward to approximately two hours past sunset. Fade off the cardinal points and suntrail.