Retrograde and prograde motion sky to temporarily reverse. The rotations of Earth and Mars are also affected by tidal forces with the Sun, but they have not reached an equilibrium state like Mercury and Venus because they are further out from the Sun where tidal forces are weaker. The gas giants of the Solar System are too massive and too far from the Sun for tidal forces to slow down their rotations. All known dwarf planets and dwarf planet candidates have prograde orbits around the Sun, but some have retrograde rotation. Pluto has retrograde rotation; its axial tilt is approximately 120 degrees. Pluto and
Atmosphere of Uranus 50° latitude (first appeared in 2007) have grown more conspicuous since then. The atmosphere of Uranus is calm compared to those of other giant planets. Only a limited number of small bright clouds at middle latitudes in both hemispheres and one Uranus Dark Spot have been observed since 1986. One of those bright cloud features, located at −34° of latitude and called "Berg", probably existed continuously since at least 1986. Nevertheless, the Uranian atmosphere has rather strong zonal winds blowing in the retrograde (counter to the rotation) direction near the equator, but switching to the prograde direction poleward of ±20°