Colour difference between Uranus and Neptune?

[michaelmorris]

I've recently been imaging Uranus and Neptune. I must admit that I'm a bit confused about the colours I'm seeing.

All the amateur pictures I can find on the interweb that show a colour difference between the two ice giants seem to show Uranus as turquoise and Neptune as blue, yet with my images it's the other way around.

Visually I can make out Uranus as a palish blue, but Neptune is so faint in the haze above Worcester that it difficult to discern any colour other than to say that it's not red or yellow. What colours are other people seeing?

[brianb]

Uranus - greenish grey - not strongly so - to recognise Uranus I need sufficient magnification to show the small disk (something over x100)

Neptune - pale blue - distinct enough to recognise the planet by its colour

Colours recorded by cameras are often affected by long or short wave radiation to which the eye is not sensitive. Even when a UV/IR cut filter is used. The dark adapted eye is particularly insensitive to red.

[Ben Ritchie]

Uranus is blue/green due to Methane absorption in the atmosphere attenuating the red. Neptune is darker blue, and from what I remember the reason isn't entirely clear - the Methane content is similar to Uranus, so there's something else absorbing green light.

edit: see http://solarsystem.nasa.gov/planets/profile.cfm?Object=Neptune&Display=OverviewLong

Neptune's blue color is the result of methane in the atmosphere. Uranus' blue-green color is also the result of atmospheric methane, but Neptune is a more vivid, brighter blue, so there must be an unknown component that causes the more intense color.

Visually I see Uranus as greenish, but i've always assumed that's because the eye is more sensitive to green than blue. My 'scopes aren't big enough to show colour in Neptune (or my eyes aren't good enough!)

[dmahon]

Your picures certainly look a very nice shade of blue and green to me.