Like the Science Museum, the Space Museum at Tsim Sha Tsui does not charge anything on
Wednesdays. It's also interesting to visit though not as overwhelming. You
can see meteorites, press exhibits to display the different constellations,
launch a multi-stage rocket (mini version) yourself, and make moon craters.
There are also other featured attractions like the virtual reality glider (where you feel like you're actually gliding though you're just strapped to some contraption), the multi-axis chair (where you're turned round and round and you feel like you're in outer space), and moon walk (where you feel what it's like to walk on the moon, where there is 1/6th of earth's gravity).
There's also a Space Theather where they have different film showings.
No photos are allowed inside so you'll have to content yourself with photos of the domed structure from the outside.