A spacecraft orbit that has a 90-degree inclination to the equator, passing over both poles in a north–south direction. An Earth polar orbit allows a spacecraft to pass over the entire surface of the planet as the Earth rotates beneath the orbital path. These low Earth orbits are especially used for mapping or surveillance missions. A spacecraft going into a polar orbit requires more fuel and power than one that uses the free ride of the Earth's rotation.

Space probes can also be placed in polar orbits, such as NASA's Lunar Prospector around the Moon and the Magellan spacecraft in a near polar orbit around the planet Venus.

ESA's Ulysses probe is in polar orbit around the Sun.