Ptolemaeus (Martian crater)
Map of Phaethontis quadrangle. Click on to enlarge and see some crater names.
|Eponym||Claudius Ptolemaeus, a Greco-Egyptian astronomer (c|
Ptolemaeus Crater is a crater on Mars found in the Phaethontis quadrangle at 46.21° south latitude and 157.6° west longitude. It is 165.18 km in diameter and was named after Claudius Ptolemaeus, a Greco-Egyptian astronomer (c. AD 90-160).
Much of the surface of Mars is covered by a thick smooth mantle that is thought to be a mixture of ice and dust. This ice-rich mantle, a few yards thick, smoothes the land, but in places it has a bumpy texture, resembling the surface of a basketball. Under certain conditions the ice could melt and flow down the slopes to create gullies. Because there are few craters on this mantle, the mantle is relatively young. An excellent view of this mantle is shown below in the picture of the Ptolemaeus Crater Rim, as seen by HiRISE.
Changes in Mars's orbit and tilt cause significant changes in the distribution of water ice from polar regions down to latitudes equivalent to Texas. During certain climate periods water vapor leaves polar ice and enters the atmosphere. The water comes back to ground at lower latitudes as deposits of frost or snow mixed generously with dust. The atmosphere of Mars contains a great deal of fine dust particles. Water vapor will condense on the particles, then fall down to the ground due to the additional weight of the water coating. When ice at the top of the mantling layer goes back into the atmosphere, it leaves behind dust, which insulating the remaining ice.
This topographic map shows volcanic peaks in white because of their great height. Near the equator, a line of three volcanoes points south to Phaethontis and three large craters-the area where there are many gullies. Click on the image for a good view.
Ptolemaeus Crater Rim, as seen by HiRISE. Click on image to see excellent view of mantle deposit.
- Blue, Jennifer. "Ptolemaeus (Martian crater)". Gazetteer of Planetary Nomenclature. USGS Astrogeology Research Program.
- Head, J. et al. 2003. Recent ice ages on Mars. Nature:426. 797-802.
- MLA NASA/Jet Propulsion Laboratory (2003, December 18). Mars May Be Emerging From An Ice Age. ScienceDaily. Retrieved February 19, 2009, from http://www.sciencedaily.com /releases/2003/12/031218075443.htmAds by GoogleAdvertise
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