Atmosphere - Uranus’ clouds are featureless blue. Neptune’s clouds show more variety and contrast than Uranus’.

Uranus - true color and false color

Atmospheric composition is similar to Jupiter and Saturn.

H - 84% He - 14% CH 4 - Neptune, 3% Uranus, 2% Not much gaseous ammonia. (Uranus and Neptune are too cold to keep ammonia in a gaseous state.)

Helium is not depleted so probably no Helium rain like on Saturn.

Jupiter - Saturn - Uranus - Neptune blue-green blue color color less CH >more CH 4 more NH >lessNH 3 CH 4 absorbs red light, so more CH 4 means a bluer planet.

Weather - Uranus - High winds spread the heat all over the planet. The dark hemisphere is almost equal in temperature to the light hemisphere. Uranus has very faint bands.

Uranus doesn’t radiate more heat than it receives from the Sun. It is the only Jovian planet that does not.

Neptune - Clouds and bands are much more easily seen. The zonal flow is retrograde to the planet’s rotation direction. The surface winds have speeds of over 2000 km/h.

Neptune radiates twice as much energy as it absorbs from the Sun similar to Saturn and Jupiter. It must have an internal heat source.

The largest storm on Neptune is the Great Dark Spot. It is about the size of Earth and is similar to Jupiter’s Great Red Spot.

Neptune also has a “scooter”; a small, irregular, white cloud that zips around Neptune every 16 hours or so.

In 1994, the Great Dark Spot disappeared. A new dark spot was found in the northern hemisphere a few months later.

Magnetospheres - About 100 times stronger than Earth’s. However, the surface fields are about equal to Earth’s because the planets are larger.

The magnetospheres are severely tilted to the rotational axis: Uranus’ - 60° Neptune’s - 46°

The fields are also offset from the center of the planets.

The two planets may have “slushy” layers of H 2 O clouds, perhaps with NH 3 dissolved.

This could make the layer ionic which could explain the presence of a magnetosphere.