Don't worry if it doesn't work, it's not for everyone
Here's a cool photo in which you can see Jupiter and its moon Europa in 3D without any glasses or any sort of equipment, or go crazy trying to cross your eyes to see the effect. Either way you win.The photo, photos actually, were taken recently from the Jaicoa Observatory in Puerto Rico. It's a shot of Jupiter, one of its best sides perhaps, and of its moon Europa, in the right image.
The trick is to stare at the center of the image intensely and try to cross your eyes. That is, if you can cross your eyes, otherwise it's just an exercise in frustration.
If you're doing it right, you should (allegedly) be able to get a nice 3D effect, since the two photos present a slightly different perspective.
If you're doing it wrong, you'll get a headache. But don't feel too bad if you can't see the effect, not everyone can.