[math-fun] Stupid antimatter questions

I read the very interesting wikipedia article on antimatter, which answered a number of my questions: http://en.wikipedia.org/wiki/Antimatter However, it didn't answer my basic question: "How do we know whether something we're looking at in a telescope is matter or anti-matter?" I.e., what features of the object gives away its matter v. anti-matter nature? Also, does anti-matter really duplicate the chemical features of matter? E.g., would anti-water freeze at 0C and boil at 100C? Could we form anti-carbon graphite, buckeyballs, etc.? I was also intrigued that 50% of the energy in matter/anti-matter collisions is carried off by neutrinos! Sounds like a pretty ideal neutrino "light" bulb to me.