To shape a cosmic body into a disk (rather than a sphere), you’ve got to spin it very fast, says David Stevenson, a planetary scientist at Caltech in Pasadena, California. This would, unfortunately, destroy the planet by tearing it into tiny particles. In the 1850s, astronomer James Clerk Maxwell showed mathematically that a solid, disk-like shape isn’t a stable configuration in the cosmos, in work he conducted regarding Saturn’s rings. Maxwell’s research predicted that Saturn’s rings would be made of lots of small, unconnected particles; he turned out to be right. His math also explains why there are no planet-size disks floating around the galaxy.
To flatten Earth without spinning it very rapidly, you’d need magic, or perhaps a galactic panini press. At any rate, a stamped-flat Earth wouldn’t last for long. Within a few hours, the force of gravity would press the planet back into a spheroid. Gravity pulls equally from all sides, which explains why planets are spheres (or nearly so – depending on the speed of a planet’s rotation, those forces may work against gravity to create a bit of a bulge at the equator). A stable, solid disk-like Earth just isn’t possible under the actual conditions of gravity, as Maxwell’s math showed.
And once you get rid of gravity, everything about our planet rapidly stops making sense.
The atmosphere? Gone, because it’s held to the planet by gravity. Tides? Gone. They’re caused by the gravitational pull of the moon, which tugs on the oceans and causes them to subtly bulge out as it swings by.
The moon itself? Also gone, since every explanation of the moon’s existence involves gravity. In the most widely accepted scenario, the moon was created when a giant, planet-size body crashed into the early Earth; debris from the crash was captured by Earth’s gravity. Another scenario suggests that the moon formed at the same time as Earth did (again, thanks to gravity). Or, Earth’s formidable gravity attracted and snagged the traveling hunk of space rock as it went hurtling by.