The Big Blue Marble? I'd never heard it called that — but then I wasn't born in 1972 when that endearing moniker described a photo of the earth taken by the crew of Apollo 17. It does sort of look like that doesn't it?
Keep your globe out of direct sunlight.
Sunlight shining through the water is a magnifier and can cause a fire. Sunlight can also cause the water to discolor.
Dust with a soft cloth; glass cleaner is fine on the globe.