This is a fun, simple, crude, and not-very-accurate simulation of planetary orbits. Control the strength of gravity by changing the value of G, get a better score by making the planet's orbit closer to a perfect circle. Can you get your planet into a circular orbit? You can show and hide orbital guidelines by pressing "o". Increase/decrease G by 1 with up/down arrow. Note, you do not need to exactly match those guidelines. They are there just to help you see how close your orbit is to being circular.
If a planet stays the same distance from its star, it can stay about the same overall temperature and life has a chance to grow. But if it keeps zooming in close and then out farther away again, it bakes and then freezes, and life has a harder time and may even be wiped out. One way to measure the shape of an orbit is called eccentricity ("ee-sen-TRIS-it-ee"). This number tells you how "flattened" the orbit is. If the orbit is a perfect circle, it is not flattened at all, and its eccentricity will be zero. But if it was totally flattened into a straight line then its eccentricity would be one. Earth's eccentricity is about 0.017, really close to zero. The Aphelion of an orbit is the farthest distance from center, and the perihelion is the smallest distance. There is a little graph at the bottom showing those distances each time your planet makes one orbit, with the difference between the two colored red. If you get your planet into a circular orbit, there will be no red there. Your score is calculated from the eccentricity by a tricky formula. The best score you've had so far is shown too. But a score will only be checked for "best" if the eccentricity is about the same for three orbits in a row - if you are randomly messing around with the gravity and happen to get one good orbit in there somewhere, that won't count as best. I've shown students how to do somewhat realistic 1-dimensional gravity before, but just now had the idea to do the same thing in 2D. Apparently I learned the wrong definition for eccentricity way back when, so for a while this program was calculating the wrong thing! #game #space #planet #orbit #gravity #science #ScienceRules
