Saturday, 24 September 2011


Temperatures vary drastically on Mercury, the closest planet to the sun. On the side that faces the sun, temperatures can reach up to 801°F, while on the other side, temperatures can drop down to -279°F, allowing for Mercury to have the most extreme temperature variations in the solar system. One reason for these temperature variations is the lack of atmosphere over Mercury to trap heat. The second smallest planet in the solar system, Mercury is rocky and cratered with almost no atmosphere to serve as protection. Caloris Basin, with a diameter of over 800 miles, is Mercury’s most notable feature and is thought to have been caused by an impact early in the history of the planet.


As we shall see on subsequent pages, while volcanic rocks predominate on Mars, there are widespread sedimentary rocks - mostly evaporites and some carbonates. The overall surface state of Mars, judging from these full planet face views, is that it consists of three major color states, each tied to some dominant material: 1) the predominant reddish colored surface, which is now known to be regions in which the rocks, soils and dust are strongly oxidized into phases consisting of hematite, and possibly maghemite (the γ polymorph of Fe2O3) and similar minerals (including the group of hydrated iron oxides going under the name of "limonite", if water at and beneath the surface has "weathered" the hematite); 2) the dark bluish to blackish surface, presumably basaltic bedrock with less iron discoloration, and 3) the whitish areas around the poles, identified as a mix of water and carbon dioxide (the outer coating). Color phase 2) implies that the surface is volcanic bedrock with insufficient iron oxide dust cover to significantly alter the color depicted; this suggests much less onsite alteration of the basalt and the transient nature of dust cover as martian winds remove much of previously deposited red dust (but some may be cyclically deposited during strong dust storms [see next page]). As an example of this dark color phase, look at the Syrtis Major physiographic region. It probably is volcanic crust, likely basalt. It size, however, varies from time to time because winds carry red dust back and forth over its boundaries.
Saturn is a large gas planet with an atmosphere composed of hydrogen and helium.It has the lowest density of any planet in our solar system. In fact its density is so low that it would float if it was placed in water! Visually, Saturn is flattened at the poles, due to the quick rotation on its axis. The winds in its atmosphere reach speeds up to 1700 kilometers per hour! Saturn is known for its extensive ring system which is formed by a thousand individual rings. They are mainly composed of water ice and dust. Planet Saturn 3D Screensaver is an extraordinary 3D representation of this fascinating planet.

kedudukan planet