Tidally

Stars Close binary stars throughout the universe are expected to be tidally locked with each other, and extrasolar planets that have been found to orbit their primaries extremely closely are also thought to be tidally locked to them.

The habitable zones around K-dwarfs are also far enough away that planets wouldn't be tidally locked, another potential barrier to habitability that affects M-dwarfs.

We always see the same side of the moon because it’s tidally locked to Earth.

All of the planets are thought to be tidally locked to their star, which means they rotate once per orbit so that one side is constantly bathed in daylight.

The moon is tidally locked, which is one we always seem the same side from Earth while never getting a peek at the 'dark side of the moon'.

And it appears there is a great problem with the atmosphere of such tidally locked planets: the perpetual night zone would be cold enough to freeze the main gases of their atmospheres, leaving the daylight zone nude and dry.

A tidally locked body in synchronous rotation takes just as long to rotate around its own axis as it does to revolve around its partner.

Callisto's rotation is tidally locked to its orbit around Jupiter, so that the same hemisphere always faces inward; Jupiter appears to stand nearly still in Callisto's sky.

For many years it was thought that Mercury was synchronously tidally locked with the Sun, rotating once for each orbit and always keeping the same face directed towards the Sun, in the same way that the same side of the Moon always faces Earth.

If Mercury were tidally locked, its dark face would be extremely cold, but measurements of radio emission revealed that it was much hotter than expected.

In other words, Umbriel is a synchronous or tidally locked satellite, with one face always pointing toward its parent planet.

Most significant moons in the Solar System are tidally locked with their primaries, because they orbit very closely and tidal force increases rapidly (as a cubic function ) with decreasing distance.

Other cases of tidal acceleration Most natural satellites of the planets undergo tidal acceleration to some degree (usually small), except for the two classes of tidally decelerated bodies.

Over the timescale of the system, it should have been tidally damped into a more circular orbit.

Ring systems may form around centaurs when they are tidally disrupted in a close encounter (within 0.4 to 0.8 times the Roche limit ) with a giant planet.

Rotation–orbit resonance Finally, in some cases where the orbit is eccentric and the tidal effect is relatively weak, the smaller body may end up in a so-called spin-orbit resonance, rather than being tidally locked.

The larger natural satellites, being tidally locked, tend toward ovoid (egg-like) shapes: squat at their poles and with longer equatorial axes in the direction of their primaries (their planets) than in the direction of their motion.

They were probably created by objects that were tidally disrupted as they passed close to Jupiter prior to the impact on Callisto, or by very oblique impacts.

This is because the smaller body becomes tidally locked faster, and by the time a synchronous orbit is achieved, it has had a locked synchronous rotation for a long time already.

This results in Pluto and Charon being mutually tidally locked.