Originally Posted by jsmih

Galaxy/stars/meteors - need a wide angle wide aperture lens. The Samyang 14mm/f2.8 is pretty cheap (around $220) and supposedly pretty good. Exposure times over 15-20 seconds will start to get star trails.

Moon - need a pretty long lens to get much more than a dot. The Canon 55-250mm would fit your camera, is sharp, and is pretty cheap (around $200). It would give you a bigger moon than your 18-55, but still not fill the frame. Remember the moon is lit by the sun (daylight), so exposures will be short.