When viewed from their planet, are moons always the same colour as ours? Or is there a variation? What other colours might be possible and what causes the differences in colour?
More or less they can be of any colour.
The colour of the moon from the point of view of someone who is in the planet is determined by four factors: The moon material, the atmospheric composition, the sun colour and the observers eye sensibility.
- First the colour of the sun, normally determined by the temperature. You probably want it to be white/yellow or white/xxx so it doesn't change the planet light.
- The moon material will be the thing you can change more as you can choose many materials with different colour reflections. For example iron oxide for red (like Mars).
- The atmospheric colour is the final filter, so you can have a brown moon and if you have a green atmosphere, the moon will be more green than brown. The colour of an atmosphere can be because of its components in different layers so maybe you can have a coloured sky but still have a breathable atmosphere in lower level.
- The sensibility of the observers eye can also filter what it perceive. Humans can see a range of frequencies that we call "visible range", but other animals can have other ranges for example bees can see in ultraviolet range. This can be affected by the sun light as it's normal for life to evolve to be more sensible to the range of light it have.
So you can combine each of the three factors to create the colour you want.
About the colour of the moon, you can search for mineral pigments to found many pigments (colours for your moon) that are more or less naturals. For example you have: lapus lazuli for blue, iron oxides for red / ochre even green (see http://www.earthpigments.com/sof-green-pigment/).
I found a page in which you can find minerals by colors: http://webmineral.com/help/Color.shtml
You can see a link about what animals see in following link http://www.colormatters.com/color-matters-for-kids/how-animals-see-color.
Of course no.
A satellite colour is the combination of
- the colour of incident light (depends on the star)
- albedo colour parameters (depends on the material of the satellite itself)
- atmospheric filtering.
Since there are blue, white, yellow, orange and red stars, that's a lot of possibilities.
With only our own Sun (orange), and no atmospheric filtering (since these photos are from space), we have these:
(Source: https://commons.wikimedia.org/wiki/File:Moons_of_solar_system_v7.jpg , Original source: solarsystem.nasa.gov , more details in original page)
I'd think much variation. Our moon is a pretty barren rock with some lava flow colouring it (lava flow is the dark spots. The other side of the moon mostly lacks this and appears much more solid white apparently).
a couple examples:
IO (moon of jupiter), would appear very yellow in the sky due to it's sulhpur composition.
Europa (another jupiter moon) is mostly ice and it's colour would be more white along with a red center.
Triton (Neptune) has a nitrogen atmosphere and will have a blueish colour
Tethys (saturn) has a yellow / sand colour to it.
A good portion of moons will look barren as ours, but there can easily be colour variations from simple make-up. Most of these pics can be readily found on google.