Gravity Lab

I've enjoyed catching up on all of your posts, now time for me to catch up too!

I used an app called Gravity Lab in my Astronomy class.  This app will calculate the orbits of objects that are affected by gravity.  You can put in a solar system by tapping the screen, then swipe your finger to add a second Sun.  As you might imagine, this messes up the beautiful orderly motions of the planets!   I've used these   simulators before, but with the iPad, the interface is very intuitive and it makes it easy to interact with your celestial creations.  You can put new objects on with a tap or swipe, and once the orbits go haywire, you can use the pinch zoom feature to zoom out.  Educationally, this illustrates Newton's laws + gravity in action and makes it clear that the orderly orbits of our solar system are a delicate and fine-tuned state of affairs. It's just so fun to muck it all up by tossing in other gravitating masses, or even whole other solar systems!  You can also fairly easily set up "gravity assist" situations, which is how we fling artificial satellites to the outer solar system.

Next up, Star Walk...