Extrasolar Planets and Orbits
Topic/Concept: Extrasolar Planets and Orbits
Type of Activity: a short introduction + small group
Prerequisite knowledge required: newton’s version of kepler’s third law (NVK3)
Resources required: worksheet, pictures (artists’ renditions) of extrasolar planets
Learning Objectives: apply NVK3 to find the semi-major axis of an extrasolar planet’s orbit, practice using ratios and comparing objects in the universe, brainstorm ways that astronomers detect extrasolar planets
Common misconceptions:
Detailed description of activity: put the students in groups of three and give each person a worksheet. on the board introduce the idea that in astronomy we like to compare new planetary systems to the earth-sun system that we are so familiar with. refresh the students on NVK3 if necessary. then help them set up NVK3 with ratios for the extrasolar planet system over the earth-sun system in order to do the first question on the worksheet. then let them work on the worksheet in their groups for the rest of the time.
the worksheet has some information on the extrasolar planetary system at the top and then the following questions: What is the semi-major axis of the planet’s orbit? Draw a picture of this orbit. What is interesting about this system? How is it different than our solar system? How do you think astronomers detect extrasolar planets? What makes it hard to do? If you lived on the surface of this planet and one day dropped a hammer and a feather at the same time, which would hit the ground first (ignoring air resistance)? Why? What would happen if gravity suddenly turned off altogether? Can you draw a picture of how the planet’s motion would change?
Assessment: this is mostly done through interacting with the students as they work in groups. you could also collect the worksheet and look over or grade it and hand it back.
Associated files and images:worksheet (tex), worksheet (pdf), worksheet with answers (tex), worksheet with answers (pdf)
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