Take the T (Red Line) to Harvard Square: $8.
Warm up with two frothy, decadent hot chocolates at L.A. Burdick, pictured (52-D Brattle St., Cambridge, 617-491-4340, www.burdickchocolate.com). If you're feeling extra indulgent, share a slice of the chocolate mousse cake. $6 (for two small cocoas); $10 (with cake).
Trek over to the Harvard-Smithsonian Center for Astrophysics (60 Garden St., Cambridge, 617-495-7461, www.cfa.harvard.edu) for its Observatory Night, held the third Thursday of each month. A non-technical astronomy lecture at 7:30 p.m. is followed by telescope viewing sessions on the roof (beginning at around 8:30). Free.
Late dinner at Grendel's Den (89 Winthrop St., Cambridge, 617-491-1160, www.grendelsden.com), where food is half-price from 9-11:30 p.m. Sunday through Thursday (and every night from 5-7:30 p.m.), with a $3-minimum beverage purchase (per person). Order a couple of burgers (hamburger, turkey, or gardenburger) and wash them down with a couple of the brews on tap: Around $15.50. Add tip: $3.