A synchronous polar orbit satallite crosses the equator at the same time each day while the sun synchronous polar satellite appears in the sky at the same time every few days. the sun synchronous allow for greater temporal and spatial monitoring under same conditions and also have finer resolution as the polar synchronous imagery is at the continental scale.

Synchronous rotation or tidal locking.

The Moon is in synchronous rotation about the Earth. Most major moons in the solar system have a synchronous rotation.

mainly alternator,synchronous motor comes under the synchronous machine.a synchronous motor is not a self starting motor.if a synchronous motor moves with more than synchronous speed then it acts as a synchronous generator.

The Sun created a significant tidal bulge on Mercury when it was still a young, molten planet; when the planet solidified, this bulge was locked in place. Mercury is so close to the Sun that the Sun's gravitational force on Mercury's tidal bulges changed the planet's rotation rate. However, Mercury's highly eccentric orbit has prevented the planet from getting locked into synchronous rotation.

a synchronous condenser is over excited synchronous motor under no load