In the summer, things fall quiet. The students leave, making for a much quieter building (and opening up lots of parking). Seminars go on hiatus. Astronomy meetings are held across the globe, so many researchers and graduate students begin globetrotting. The net result is a very quiet building.
We often joke that summer is the time that all the astronomy gets done. Distractions are gone, and we can sit for weeks without interruption and crank out research paper after research paper. Of course, this isn't exactly true. Yes, most people do get more research time in the summer (because they aren't teaching classes, although since I am teaching a summer course, I don't get this benefit). But, with all of the running around to meetings, family vacations, etc., I think most people find their summers just as distracting as the rest of the year. As for me, I'm happy just to have the easy parking and not having to share the elevator with 20 students riding for only one or two floors. As for the work, it'll get done eventually.