Astronomy appearing in a dream is an announcement that you will discover new features in yourself that you have not expected at all, they may be e.g. new behaviors or talents.
learning astronomy - means that if you focus on the positive sides of the situation in which you find yourself you can easily cope with your weaknesses and problems
astronomy at school - you will surely achieve your goals soon
if you are interested in astronomy - you will see your own life in a completely new version, some events will be stimulate you to make new changes
if you are an astronomer - you will discover things that are too difficult for a mere mortal to understand.
More dream interpretation: