Hidden out in Southold is a great astronomy museum! It's small with some exhibits and artifacts (even meteorites) but you are here for more hard core stuff. It is the observatory, which has a great telescope (10 inch reflecting and 5 inch refracting for you real astromony buffs) which is fun to look into. Also, the world's largest pair of refracting binoculars (quick-close those drapes!). with a 10 inch aperture. Museum is open sat afternoons, observatory open sat after 8 pm . Call ahead. Free!