Meteor Storm Globe

is the globe solid or in two pieces?

Do you have to keep the on button push in for it to work? Or just click the on button? My son is special needs and would not comprehend having to hold the button. Thank you.

Does this have an on/off button or does the button have to be held continuously to run the toy?

How do I install the batteries? I see an opening at the back but cant figure out how to open it