| Mercury Key point: Influence of position near Sun on evolution compared with that of the moon
(to right, courtesy NASA; above, Buddha, the
planet Mercury, the son of Chandra (the Moon) and Tara (the
North Star). from The Black Peacock, http://www.goloka.com/index.html)
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Superficially like the Moon (from http://sci.esa.int/science-e-media/img/05/4550.jpg)
But----
Denser (large metal core).
Significant magnetic field compared to Moon’s weak field.
Surface shows effects of great heat and melting.
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The double ringed crater almost looks like a splash in a semi-liquid surface, and all the craters are flat as if the surface were not rigid enough to hold up high walls. (From SEDS, http://www.solarviews.com/cap/merc/dublring.htm) |
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Mercury's rotation (its
"day") is synchronized with its orbit (1 rotation per 2/3 orbit around the Sun).
The average surface temperature is high because Mercury is so close
to the sun. However, there is no atmosphere to carry heat from one part of the surface
to another. In addition, the very long "day" means that part of the surface is
exposed to the sun for a long time while the other part cools to deep space. As a result,
there is a huge temperature range on the surface - from 120oK to 720oK.
This painting tries to capture the harsh conditions on the surface of Mercury, by William Hartmann |
Test your understanding before going on
 Thoth, Egyptian moon god
http://www.startistics.com/ophiuchus/familyalbum.htm |
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Mayan Venus deity, from the Borgia Codex, http://members.shaw.ca/mjfinley/4VENUS.htm |
Click to return to syllabus |
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| Click to return to the moon | hypertext |
Click to go to Venus |
G. H. Rieke