Astronomy

  Transcript Under a dark sky, you can see thousands of stars. If you watch for a few hours, you can see them rise and set as the Earth rotates once a day. And if you go outside the next night at the same time, you’ll see that things’ll look pretty much the same as they did the night before. The stars rise and set, Polaris hangs to the north, and so on. One day hardly makes any difference to the sky’s appearance. But what if you wait for another night? Or a week? If you’re that patient, and observant, you can spot subtle changes in the sky. Let’s say a couple of weeks have passed. Remember that star that was just over a tree in the east when the Sun set -- the one that made you first notice the stars are rising and setting? Go look at it again. If you happen to be out at the same time, you’d expect that star to be in the same place. But it’s not. It’s actually a bit higher above the tree. And if you look west, stars that were well off the horizon just after sunset last week are now...