Activities for Big Audiences

One of the questions planetarians have faced in the past couple of decades is, "Can we compete in the ever accelerating world of dazzling movie special effects?" One area in which movies can never compete is in the realm of audience participation.

The tradition of audience participation in planetarium shows goes back a long ways. Even in the venerable "lecturer under the stars" style, the lecturer was live and could respond to questions from the audience, though the extent to which a lecturer would encourage questions was often minimal.

Acoustics of large domes are excellent, so the presenter and audience being able to hear an unamplified voice from the audience is not a problem, as long as the person speaks up loudly. Of course, "speaking up" in a large group is an intimidating prospect for many folks, so it is good to learn tricks and techniques that encourage people to ask questions or to answer questions. To encourage questions, simple invitations can be used:

• Does anyone have a question at this point?
• Are there any questions that come to your mind?
• Feel free to ask a question if you think of one. Since I cannot see everyone very well, just say out loud, the word "QUESTION" if you would like to ask something, and that will be my cue to say "Yes, there is a question?"

In PASS volume 7, Moons of the Solar System, a light bulb is a model Sun in the center of the planetarium, with a shield over it so it does not cast light on the dome, but only sideways towards the audience. In a small planetarium, the presenter can hand each visitor a small white polystyrene ball as a model Moon.

Each visitor's own head is their model Earth. Moving the model Moon around your own head is a vivid illustration of how phases happen. Children as young as 6 years old enjoy this activity, though it is likely that mostly children over 8 years old really begin to grasp the concept and full understanding of the cause of phases for many people may not occur until middle school. The activity is effective at various levels for all ages of visitors.

In a large planetarium, handing out items to each visitor is usually not an option. However, demonstrations can be effective, especially with volunteers from the audience. In the case of the Moon phase modeling, Chabot Planetarium in Oakland, California successfully used a video camera to demonstrate the moon phase modeling activity. The "Earth" volunteer holds the video camera pointing at the model Moon as it circles. The live camera image is projected onto the dome so that everyone can see the Moon from the Earth-centered perspective which is the most important element of the model. This sort of video demonstration technique could apply to other activities that involve props that would normally be handed out in a small planetarium.

A lot of our activities involve paper and pencil to record observations. For example, in Moons of the Solar System, each visitor analyzes the movement of one of the Galilean moons each night for 9 nights by recording the position on paper, just as Galileo did. From their records, they can deduce the periods of the moons and see a relationship with orbit radius. A similar series of observations is done in our Mysteries of Missing Matter program, in which the audience keeps track of the movement of Uranus, and notes a discrepancy leading to the discovery of Neptune.

A big dome can accomplish such "paper and pencil" activities in a couple of ways. One strategy is to make it demonstration mode. The audience observes and directs the presenter what to write on a single, whole-audience, projected data sheet. Projection can be by overhead projector or computer input videoprojection, with live input by the presenter.

Another strategy for "paper and pencil" in big domes is ... paper and pencil! To write on paper, visitors need a stiff surface which can be a clipboard hung by each seat, or the paper itself can be folded cardstock that is easy to write on even without a clipboard. The logistical problem of how to get the paper and pencil into the hands of the visitor can be solved by

a. keeping materials near the seats, e.g. in holders attached to the seat backs, or

b. making a small gift along with the ticket purchase: a paper "program" sheet and a "gift pencil," maybe even with the planetarium name on it. People are used to getting paper programs with show events, so the paper part would not be unusual to them and the 25-cent gift would be good promotion.

Happily, many of the best activities involve no hands-on props at all. They are more in the nature of "eyes-on" (observations) and "minds-on" (analysis) activities. Several of our programs have sections in which visitors mark the rising and setting objects on the horizon. In very small domes, visitors can each get a horizon marker and walk over to the horizon to place their marker. In a big dome, the horizon may be pre-marked in sections using a simple panorama projection that divides the horizon into sections: North, Northeast, East, etc. There can be finer divisions also: North Northeast, Northeast, East Northeast, East, etc.

One of the most fun and enlightening activities involves the audience observing a sunrise, marking the sunrise position on the horizon, then predicting where the Sun will set. In a big dome, they can predict in which section of the panorama-projected horizon they think the sunset will occur. A push-button voting system or even simple raising-of-hands voting system can be used effectively to get a sense of what most of the audience is guessing. It is usually a big revelation to people that the Sun does not necessarily set on the exact opposite position on the horizon from where it rose.

In the program Constellations Tonight, PASS Volume 5, each audience member gets a simple star map of the current sky and learns how to use it to find constellations. When the show is over, the visitor has learned a skill with a tool to take home, so they can find the constellations in the real sky. In small planetariums, the audience is divided into small groups with specific constellation-finding assignments. Each group then uses a battery powered light pointer to show their constellation to the rest of the audience. Can you think of a strategy for a star map activity in a big dome?

One strategy is to create a sort of multiple choice system, with small numbers projected onto each constellation. Give the audience star maps with their admission. To verify if they have found a constellation, you can ask, for example, "Which number is in the constellation Leo?" Again, a push-button vote system or raise-hands voting can work just fine. Another helpful strategy in explaining how to use star maps is to project a star map onto the dome, while explaining the steps in using it.

Another interesting activity is in our program Target Earth, where the audience estimates the frequency of large impacts on Earth by counting the number of large craters in the lunar maria, using some simple assumptions and a little arithmetic.

• -- Moon rock samples collected by astronauts have shown the maria to be about 4 billion years old,
• -- The Earth's surface area is about 80 times the surface area of the visible maria.
• -- Assume the Earth was, by proximity to the Moon, exposed to the same type of asteroid or comet encounters, but Earth was more likely to be hit since it is bigger.

As you can see, there are many possibilities for audience participation in large theaters. I invite all large planetarium people to share ideas for big dome large audience activities. I offer to act as a clearinghousea sort of "Big Audience Activities Users Group." Any new ideas that are offered will be posted on the PASS website http://www.lhs.berkeley.edu/pass/AST300.html, under "News and Updates" for PASS Volume 1, Planetarium Educators Workshop Guide. Send me your contributions to post!

Alan Gould <agould@uclink4.berkeley.edu>