Stellarium is one of the great under-sung feats of open-source. And it's great for learning. A person may have learned to identify many objects in the sky. The

Stellarium is one of the great under-sung feats of open-source. And it's great for learning. A person may have learned to identify many objects in the sky. The planetarium feature (motion at various rates) makes it much easier (and faster) to comprehend how it all fits together at various times of the day and of the year. Fascinating. For example, turn on the line of the ecliptic and watch its motion around 'due south' as the day goes by. (Wild at this time of year.) Or tell the program to 'track' a constellation (e.g. Orion) and then fast-forward by days to see how it rises/falls wrt the horizon because of the Earth's tilt. Or watch (and try to figure out) why the Moon moves all over the sky.