Considering the pony is hovering by flapping her wings serenely, very loosely indeed.

"Earth ponies raise the crops and tend to the animals. Pegasus ponies are in charge of weather, like making clouds or clearing them, or making rainbows. Unicorns change the seasons. Princess Celestia raises the sun, and Princess Luna raises the moon. There's kind of a story behind that but it doesn't have much to do with how the world works."