The equator is an essential component of our planet’s geography—even though it’s just an imaginary line drawn on a map. In addition to being the widest spot on the planet—a full 43 kilometers (27 miles) wider than at the poles—this is also the planetary dividing line for the Coriolis effect, which explains why cyclones rotate clockwise north of the equator and counterclockwise south of it. It’s also the place best suited for launching spacecraft because the gravitational pull gives rocket ships an extra boost out of the stratosphere. And for a bit of light-hearted fun, if you’re onboard a craft where any of the crew are crossing this imaginary line for the first time, you’ll likely witness a King Neptune (or Crossing the Line) ceremony. This ancient naval tradition puts newbies, or “Pollywogs,” through a series of pranks and tests to prove themselves worthy of being a son or daughter of Neptune, the Roman god of the sea.