Look at a map of the world's major launch sites and a pattern jumps out: they cluster near the equator and near coasts. This is not an accident of geography or politics. It is physics. The Earth spins, and a rocket standing on the equator is already moving eastward far faster than one standing near the poles, before its engines even light.

That free speed matters enormously, because reaching orbit is mostly about going fast sideways rather than going high. Every bit of velocity a rocket gets from Earth's rotation is velocity its engines do not have to produce, which means less fuel, more payload, or both. For heavy launches, that difference decides whether a mission is possible at all.

The Earth rotates once per day, and a point on the equator travels much further in that day than a point near the poles, so it moves much faster. At the equator that rotational speed is roughly 465 metres per second eastward. At mid-latitudes it is lower, and at the poles it is zero. A rocket launched eastward from the equator starts its flight with that speed already in hand.

Orbital speed in low Earth orbit is roughly 7.8 kilometres per second, so the equatorial boost is a meaningful fraction of the total, and it comes completely free. That is why launches to equatorial orbits, such as communications satellites over the equator, benefit most: the rocket's starting speed points exactly where the destination orbit needs it.

Coastal locations serve a second safety purpose. Rockets drop spent stages and, occasionally, fail, and operators want that debris falling into empty ocean rather than onto towns. East coasts are preferred because most launches head east to gain the rotation boost, so the flight path carries the rocket over water from the start.

Geography also explains the exceptions. Launches to polar orbits, which pass over the poles, gain nothing from equatorial rotation and instead fly north or south from high-latitude sites. Mission destination decides the ideal launch site, which is why different spaceports specialise in different orbits.

This physics is why Europe launches from French Guiana, close to the equator in South America, rather than from mainland Europe, and why American launches favour Florida over northern states. The extra speed from a low-latitude site is worth the logistical cost of operating far from home.

It is also why equatorial launch is not just a nice bonus but a competitive advantage. A rocket that starts faster can carry more cargo, use less fuel, or reach an orbit its rivals cannot. In spaceflight, where every kilogram counts, a free push from the planet itself is an advantage no engineer would turn down.

Not every launch site is on land. Some rockets launch from ocean platforms, which can be sailed to the equator for the maximum rotation boost and positioned so the flight path avoids populated areas entirely. Sea launch trades the convenience of a fixed base for flexibility in launch location, and for certain orbits that flexibility is worth the complexity.

Floating platforms also solve a political problem: a launch site in international waters does not need permission from a host country for each flight path. The idea has been used for commercial launches and remains attractive for future equatorial missions. Whether from land or sea, the principle is identical: start as close to the equator as practical, and head east over empty water.