It helps you see things either side of the ball if you're offset from the centre. Forgive the hasty diagram but https://imgur.com/a/aoZIZTs https://imgur.com/a

It helps you see things either side of the ball if you're offset from the centre. Forgive the hasty diagram but https://imgur.com/a/aoZIZTs https://imgur.com/a/aoZIZTs The Earth is entirely in-between the wildly out of scale Sun and the Moon, but a giant standing on the "top" of the Earth can see both.