This simulation adds a comet (an imaginary one) to the Solar system. It shows the comet's orbit - it doesn't (yet) show what you would see of an real comet (as long as it was bright enough); its coma and tail as it passes near the Sun.
The simulation displays two simultaneous views of the Solar system; a selection of mostly 3D views and and a choice of (top, front or side) plane views that allow you to change the velocity objects in the simulation.
The plane views show the velocity (blue arrows) of and force (red arrows) on the Sun, planets and the comet.
To change the orbit of any object,
pause the simulation
then use the mouse on any the
the plane views
(top, front or side) to alter its velocity.Experiment changing the comet's trajectory - and watch what happens. Click
rewind to return
the simulation to its original state.The energy and orbital period of the comet is shown in a scrolling graph. While the comet moves closer to the Sun its gravitational potential energy is converted into kinetic energy. As it moves away from the Sun the kinetic energy is converted back to gravitational potential energy. All the while the comet's total KE+PE remains constant (except when there are interactions with other objects in the Solar system).
As long as the comet's total energy is less than zero, it will remain in a closed orbit around the Sun (providing it doesn't crash into it, or get diverted by another object in the Solar System).
If you adjust the comet's velocity so that its total energy is greater than zero - then it will completely escape the Sun's gravitational pull.
Notes:
The comet's gravitational potential energy is always registered as negative - below the horizontal "zero" line on the graph. This is because, by convention, we say that the gravitational potential energy between two objects is zero when they are an infinite distance apart. Since this is also their maximum potential energy, the potential energy for objects a finite distance apart is less than zero.
This may seem confusing, but it is actually the simplest way of defining gravitational potential energy. Otherwise we'd have to specify some arbitrary separation for zero PE, and we'd have to deal with both positive and negative PE.
The "top" view looks "down" on the ecliptic plane - and shows velocity and force in that plane.
The ecliptic plane is the plane of the Earth's orbit around the Sun. It is so named because (lunar or solar) eclipses can only happen as the moon crosses this plane.