NAME:
Planet Migration
Go to http://phet.colorado.edu/sims/my-solar-system/my-solar-system_en.html. This
website loads a simulated solar system.
This simulation uses only gravity to show the motions of the celestial objects. Initially
there is just a star (the yellow dot in the center) and one massive planet (the purple dot).
Press the “Start” button and watch the two objects orbit.
1. Which object has a larger orbital radius?
2. Which object has a longer orbital period?
3. Which object feels a stronger force: the star or the planet? How do you know?
4. Use Newton’s laws to explain why the star moves.
5. Use Newton’s laws to explain why the star’s orbit is smaller than the planet’s.
Under “number of bodies,” select “4” to add two more planets. The mass of “body 2”
should be “10,” and the mass of “body 3” and “body 4” should be “0.01”. Experiment
with the velocity and position parameters by dragging the bodies and arrows with your
mouse and pressing “Start.” By default, the bodies are arranged so that two of them orbit
each other in addition to orbiting the star. Rearrange the planets so that they do not orbit
each other, just the star.
Find a configuration that causes the smaller planets to be ejected from the system.
6. What situations cause a planet to be ejected from the system?
7. What happens to the orbit of the large planet when an object is thrown from the solar
system?
Find a configuration that causes a smaller planet to be drawn into the central star.
8. What happens to the orbit of the large planet when an object is drawn into the central
star?
9. Explain your answers to questions 7 and 8 using Newton’s 3rd law or the conservation
of angular momentum.