Join in expert discussion on the topics of Astronomy and astrophysics. This may include discussion on celestial objects, space, and the physical universe as a whole. Mainstream science only.
Astronomy generally refers to the act of observing things (be that stars, galaxies or whatever) which, coupled with astrophysics, aims to understand those things for their own sake. The aim is to learn about the stars, galaxies or planets etc.
Astronomy, both observational and theoretical (and now also experimental!) is about what is going on in the universe that we can see now, or extrapolate to short times (~a billion years) in the past or future.