View Full Version : Why do all the gas giants look different?

2009-Jul-15, 11:16 PM
When I look at photographs of the outer planets, Jupiter has strongly contrasting bands, mostly white and orange and salmon-colored. With Saturn, the bands are still clearly visible, but with a lot less contrast, and the colors are mostly varying shades of pale yellow. Neptune is a beautiful saturated blue, and while the bands are still visible, they're difficult to pick out.

What's the reason these planets look so different, especially as regards to color? Aren't they all methane/ammonia atmospheres? (Or am I mistaken in that idea?)

2009-Jul-15, 11:54 PM
Different gasses reflect different colors...

thoth II
2009-Jul-15, 11:59 PM
they have different temperatures, which should cause different equilibrium concentrations and that would contribute to a difference between Jupiter and Saturn.

Neptune and Uranus have more methane.

2009-Jul-16, 01:31 AM
I believe their different rotation speeds play into how the bands look, too. At the Adler Planetarium in Chicago they have an interesting illustration of this - there's a sphere filled with a liquid with glitter suspended in it that spins on bearings. The glitter shows how the liquid is flowing inside the sphere, and spinning it at different speeds will produce a wide range of patterns.

2009-Jul-16, 11:56 PM
Saturn has a haze layer in it's upper atmosphere, which reduces the contrast of the color of the clouds beneath.

Uranus as the most bland color of all, with very low contrast - probably due to it's 97.7 degree axis of rotation.

2009-Jul-17, 12:05 AM
uranus is a touch boring.... but good for skimming for fuel in frontier elite 2....... oh yeah a great game

2009-Jul-17, 01:48 PM
More basic: take a dozen different colors of paints. Drip them into a dozen different bowls of water and make one swirl with a stick. None of 'em are gonna look the same.

The Universe has some randomness to it....

2009-Jul-18, 08:02 AM
The best summary I have read of the science behind the appearance of gas giants was written by Jim Whatmough; he not only discussed the various types found in our solar system, but also the appearance of various kinds of extrasolar planet.
Here it is;

Temperature is the most important factor in most cases; most gas giants probably have fairly similar atmospheres, mostly hydrogen and helium, but traces of other materials (methane, ammonia, water, sodium, iron, silicates) form clouds and haze at various temperatures. The rate of rotation would then affect the cloud patterns, and those giants which are at the right temperature to show clear banding could themselves be very diverse in apearance.

More on the classification and appearance of gas giants here

2009-Jul-18, 06:59 PM
Some gas giants I've made for Celestia; all these are made from processed images of Jupiter, and would all count as Sudarsky class I (ammonia clouds) I suppose.