The Earth is not flat; it is round, or more accurately, an oblate spheroid, meaning it bulges at the equator and is slightly flattened at the poles. This shape is caused by Earth’s rotation and is a consequence of gravity, which pulls matter into the most compact, spherical form possible. Evidence for the Earth’s round shape includes satellite imagery, the way ships disappear hull-first over the horizon, differing time zones, and the curved shadow Earth casts on the moon during a lunar eclipse.