Divide your group into two subgroups. Have one subgroup use Figure 18.17 to develop a hypothesis of what our solar system would be like today if the gas in the solar nebula had been swept away when the temperature at the inner edge of the nebula was still much higher than 1000 K. Have the other subgroup hypothesize what the solar system would be like if the gas hadn't been swept away until the temperature at the inner edge of the nebula had fallen to 300 K. Have the two subgroups compare their results with the actual solar system and with each other. Discuss the implications of your hypotheses for what other planetary systems might be like.
With the help of Figure 18.2, use binoculars to observe the Orion Nebula. See how many members of your group can see the Orion Nebula without binoculars. (You should do this in winter or spring when the constellation Orion is in the sky in the evening.)
