Star trails:

The stars would appear to move very little if if were not for our rotation on our axis once every 24 hours.  However, this motion of the earth makes it appear that the stars are changing positions during the night, as they seem to make arcs around the north star (which is more or less oriented right in line with the axis of the earth).  Recently, I took a picture of the stars above my house; I put the camera on a tripod and left the shutter open for about 20 minutes.  Notice the way the stars appear as streaks, indicating that they moved over this period.  You can notice this by going out and finding a familiar constellation, taking note of where it is early in the evening, and then returning to look at it later.  It will have moved -- or I should say, we will have moved!

It is easy to start to learn some of the most prominent constellations (patterns of stars in the sky).  Some are only visible for part of the year (since the position of the sun makes it impossible to see some stars at one point or another in yearly our revolution ).  Some, like the Big Dipper, are visible all year.  Remember, constellations are determined by what looked like meaningful patterns to previous generations of humans; stars in a given constellation may be unrelated to one another -- only human imagination has linked them.  A very basic current star chart is available from the "Basic Star Map" link at: http://www.currentsky.com/skywatch.html