A Sun-Synchronous Orbit (SSO) is a near-polar LEO orbit in which the satellite crosses any given latitude at the same local solar time on every pass. This is achieved by precisely tuning the orbital inclination (typically 96-99 degrees) so that the gravitational influence of Earth's equatorial bulge causes the orbital plane to precess at exactly one revolution per year, staying synchronized with the Sun.
SSO is the orbit of choice for Earth observation and remote sensing satellites because it provides consistent illumination conditions, making it easier to detect changes over time. Nearly all commercial imaging constellations, including Planet Labs' fleet and ICEYE's SAR satellites, operate in SSO.