There are eight groups in the sci.astro hierarchy:

sci.astro               Astronomy discussions and information.
sci.astro.seti          The Search for ExtraTerrestrial Intelligence (SETI)
sci.astro.amateur       Amateur astronomy equipment, techniques, info, etc.
sci.astro.fits          Issues related to the Flexible Image Transport System.
sci.astro.hubble        Processing Hubble Space Telescope data. (Moderated)
sci.astro.planetarium   Discussion of planetariums.
sci.astro.research      Forum in astronomy/astrophysics research. (Moderated)
sci.astro.satellites.visual-observe
                        Visual observing of artificial satellites
                        
By default, everything that is related to astronomy/astrophysics and
is NOT covered by one of the other sci.astro.* groups is acceptable
for posting in sci.astro.  If something belongs in one of those
groups, then it does NOT belong in sci.astro and should NOT be
(cross)posted there.  In particular, this includes all amateur
observations, hardware, software, and trade (see sci.astro.amateur).

The sci.astro hierarchy is NOT the appropriate forum for

  * metaphysical discussions (try alt.paranet.metaphysics);
  * astrology (alt.astrology); or
  * creationism (talk.origins for that). 

These are science groups, not religion, sociology, or philosophy (even
of science) groups.

In addition, a number of topics related to astrophysics are better
suited for other groups.  For instance, elementary particle physics
should be discussed in sci.physics.particle (but discussions of
astronomical consequences are welcome in sci.astro).  Likewise for
photons and the speed of light (sci.physics).  Finally, all space
related issues (e.g. spacecraft and faster than light/time travel)
have a home in the sci.space.* hierarchy (but astronomical results
from space missions are welcome).