NetLogo User Community Models
(back to the NetLogo User Community Models)
by Toby Skinner
WHAT IS IT?
This is a model for the eventual demise of our Solar System.
Our Solar System is held in place by a delicate balance of opposing centripetal and centrifugal forces. As our Sun generates energy by fusing its hydrogen, its loss of mass reduces the centripetal force, necessitating a reduction in the centrifugal force, as manifested by reduced orbital velocities for each of the planets. As each planetís orbital velocity falls below a threshold, it is ejected from the Solar System. When all of the planets have left the confines of the Sun, our Solar System ceases to exist.
HOW IT WORKS
Each Earth-year, the Sun's mass is updated based on the selected annual percentage mass loss. The (slower) orbital velocity for each of the planets is updated based on the Sun's new mass. Planets whose orbital velocities have fallen below their thresholds are erased from the view.
HOW TO USE IT
(1) selects an annual percentage mass loss for the Sun using a "slider",
(2) creates the Solar System by pressing a "button",
(3) sets the Solar system in motion, toward its demise, by pressing a second "button". and
(4) when all of the planets have ejected, the simulation halts, with the final
elapsed time in Earth-years displayed on a "monitor".
It is recommended that the user select an annual percentage of Sun mass loss in the range from 0.01% to 1.0%. Higher values execute instantaneously; lower values execute in excessive amounts of time.
THINGS TO NOTICE
Three windows in the view provide real-time data on the progress of the simulation:
1. The main window shows the Solar System, with progressively shrink Sun and
slowing and ejecting planets.
2. A "moniter" counts the passage of time in Earth-years.
3. A "plot" graphs the declining Sun mass and decreasing orbital velocities.
THINGS TO TRY
1. Set the "Pause" slider to on, press the "Create Solar System" button, and then
press the "Rotate Planets" button to see the relative orbital velocities portrayed, after the Earth completes one revolution.
2. Set the "AnnualSunMassLossPercent" slider to different values and engage the
simulation, to observe the relationship between the rate at which the Sun loses
mass, and the number of years remaining for our Solar System.
3. Set the "AnnualSunMassLossPercent" slider to an initial value, engage the
simulation, and change the sliders value during execution (faster or slower) to
observe non-linear relationships between the rate at which the Sun loses mass, and
the number of years remaining for our Solar System.
EXTENDING THE MODEL
1. Add the terminal special effects of the Sunís gaseous radius extending beyond the
inner planets, in the final millions of years, to create a hybrid theoretical view
of the end of the Solar System.
2. Conduct simulation experiments with non-linear rates of annual Sun mass loss, and
observe the effects on Solar System longevities.
3. Learn or develop some physics for the selection of the orbital velocity ejection
thresholds, and incorporate that knowledge into the model.
CREDITS AND REFERENCES
Created by Toby Skinner, at Portland State University, for CS-346, Fall 2011.