Trust your eyes! Planets do have colors that reflect what their surfaces are made of. From far way in space, the Earth looks blue becasue most of the surface is ocean. However, the more distant planets are very far from the Sun, so the amount of ambient light is much weaker. Pictures sent back by NASA interplanetary probes are sometimes enhanced to show features that would be missed by an Astronaut's eyes if she was that far away. Cameras also can detect infrared and UV light which humans cannot see, so scientists must give them visible colors to interpret. This is called "false color" and if scientists have done this to a photograph, they usually explain in the caption what they have done. For example, they might make the parts of the mage in the infrared a red color and the UV a blue-ish color.

John Vallerga

Hello,

You may have seen some photos of the planets that have been enhanced with "false color" or taken using special colored filters. These types of images were created using technology to help scientists see the features of the planets more clearly. If you see a caption for a photo of a planet that says it has been enhanced, uses false color, or taken using a colored filter, then the colors in the image are not the true colors you would see if you looked at the planet with your naked eye. However, the planets really are very diverse and colorful.

The planets and their moons look different from one another and have different colors in pictures because of differences in the chemical compositions of their atmospheres and their surfaces. The surface of the Earth appears to be many different colors like blue, green, brown, and white depending upon the materials (water, vegetation, rocks, ice) covering its surface in different areas. The surface of Mars appears reddish brown because of iron oxides in the rocks covering its surface, but white colored ice caps can be seen near the poles of Mars. I think that one of the most interesting and colorful bodies in our solar system is Jupiter's moon Io. Io is blotchy and multi-colored due to frequent volcanic activity that spews sulfur compounds and molten rock onto its surface. Io sort of looks like a giant pizza in space. If a planet has a very dense atmosphere, like Venus, or is one of the gas giants, like Jupiter, the colors we see in a photo are due to the composition of the gases in the planet's atmosphere and how they reflect and scatter light. You may have seen photos where Saturn looks sort of yellowish, and other photos of Saturn where it looks more blue. The mysterious changing colors of Saturn are just due to the camera angle at which the photo was taken by the spacecraft and the scattering of light by Saturn's atmosphere.

You can learn more about Io and the blue skies on Saturn here:

Jupiter's moon Io: http://solarsystem.nasa.g...rofile.cfm?Object=Io

Blue Skies on Saturn: http://science.nasa.gov/h...17feb_bluesaturn.htm

Kris