Space enthusiasts will get a big bang (pun!) out of the Adler. There are public telescopes to view the stars (10am to 1pm daily, by the Galileo Cafe), 3-D lectures to learn about supernovas (in the Space Visualization Lab), and the Planet Explorers exhibit where kids can 'launch' a rocket. The immersive digital films cost extra (from $13 per ticket). The Adler's front steps offer Chicago's best skyline view, so get your camera ready.
There's also much to see outside the Adler, and for free. Check out the 12 sides of the 1930s building, one for each sign of the zodiac. Sculptor Henry Moore's sundial keeps time by the main entrance, while the bronze Copernicus statue lords it over the front median.