Start your week off with an astronomy lecture at the Presidio Observation Post on Tuesday night, and on Thursday explore the science of extinction at NightLife at the California Academy of Sciences. If you want to get the SF Carnaval party started early, head to the Elbo Room for the official kick-off celebration, or take a seat at the Nourse Theater with filmmaker John Waters and Adam Savage. San Francisco pays tribute to legendary gay-rights advocate Harvey Milk on Friday, and afterwards you can boogie the night away at Mezzanine at their Dance Free event. Get ready to party this weekend at Carnaval in the Mission, rap with Juicy J at the Fillmore, and hit the dance floor at a special edition of Non-Stop Bhangra at Public Works. On Sunday be sure to make your own yarmulka at Broke-Ass Stuart's Bar Mitzvah Party at the Rickshaw Stop.