by neufer » Wed Aug 01, 2018 5:37 pm
De58te wrote: ↑Tue Jul 31, 2018 10:17 am
emanueldewitt wrote: ↑Tue Jul 31, 2018 8:09 am
What are we seeing? 1 m? 1 km? 100 km?
Giving an idea of length/distance in a photo would be a good custom.
According to the 'image' link, the Southern Mars Cap is around 350 km in diameter.
https://en.wikipedia.org/wiki/Martian_polar_ice_caps wrote:
<<The south polar permanent cap is much smaller than the one in the north. It is 400 km in diameter, as compared to the 1100 km diameter of the northern cap. Part of the ice cap consists of dry ice, solid carbon dioxide. Each winter the ice cap grows by adding 1.5 to 2 meters of dry ice from precipitation from a polar-hood of clouds. In summer, the dry ice sublimates (goes directly from a solid to a gas) into the atmosphere. During each year on Mars as much as a third of Mars' thin carbon dioxide (CO
2) atmosphere "freezes out" during the winter in the northern and southern hemispheres. The south polar cap is higher in altitude and colder than the one in the north.
The residual southern ice cap is displaced; that is, it is not centered on the south pole. Studies have shown that the off center cap is caused by much more snow falling on one side than the other. On the western hemisphere side of the south pole a low pressure system forms because the winds are changed by the Hellas Basin. This system produces more snow. On the other side, there is less snow and more frost. Snow tends to reflect more sunlight in the summer, so not much melts or sublimates. Frost, on the other hand has a rougher surface and tends to trap more sunlight, resulting in more sublimation.
Research, published in April 2011, described a large deposit of frozen carbon dioxide near the south pole. Most of this deposit probably enters Mars' atmosphere when the planet's tilt increases. When this occurs, the atmosphere thickens, winds get stronger, and larger areas on the surface can support liquid water. Analysis of data showed that if these deposits were all changed into gas, the atmospheric pressure on Mars would double. There are three layers of these deposits; each is capped with a 30-meter layer of water ice that prevents the CO2 from sublimating into the atmosphere. In sublimation a solid material goes directly into a gas phase. These three layers are linked to periods when the atmosphere collapsed when the climate changed.>>
Popeye wrote: ↑Wed Aug 01, 2018 4:09 pm
https://en.wikipedia.org/wiki/Sputnik_Planitia wrote:
<<The informal name Sputnik Planum was first announced by the New Horizons team on a press conference on 24 July 2015. A planum is a flat region of higher elevation (a plateau). When topographical data was analyzed in early 2016, it became clear that Sputnik is actually a basin, and the informal name was changed to Sputnik Planitia.
Sputnik Planitia is presently close to the anti-Charon point on Pluto, a result that has less than a 5% probability of arising by chance. Sputnik Planitia, the western lobe of the "Heart", is a 1,000 km-wide basin of frozen nitrogen and carbon monoxide ices, divided into polygonal cells, which are interpreted as convection cells that carry floating blocks of water ice crust and sublimation pits towards their margins; there are obvious signs of glacial flows both into and out of the basin. It has no craters that were visible to New Horizons, indicating that its surface is less than 10 million years old.
A high seasonal thermal inertia of Pluto's surface is an important driver of deposition of nitrogen ice at low latitudes. These latitudes receive less annual insolation than Pluto's polar regions due to its high obliquity (122.5°).
The coldest regions on Pluto, on average, are at 30° N. and S. latitude; early in Pluto's history, ice would tend to accumulate at these latitudes in a runaway process due to the positive feedback association of increased albedo, cooling and further ice deposition (similar to the ice segregation that occurred on Iapetus). Simulations suggest that over a period of about a million years, the runaway process would collect much of the ice into a single cap even in the absence of a preexisting basin.>>
[quote=De58te post_id=284578 time=1533032272 user_id=141631]
[quote=emanueldewitt post_id=284577 time=1533024599]
What are we seeing? 1 m? 1 km? 100 km?
Giving an idea of length/distance in a photo would be a good custom.[/quote]
According to the 'image' link, the Southern Mars Cap is around 350 km in diameter.[/quote][quote=" https://en.wikipedia.org/wiki/Martian_polar_ice_caps"]
<<The south polar permanent cap is much smaller than the one in the north. It is 400 km in diameter, as compared to the 1100 km diameter of the northern cap. Part of the ice cap consists of dry ice, solid carbon dioxide. Each winter the ice cap grows by adding 1.5 to 2 meters of dry ice from precipitation from a polar-hood of clouds. In summer, the dry ice sublimates (goes directly from a solid to a gas) into the atmosphere. During each year on Mars as much as a third of Mars' thin carbon dioxide (CO[sub]2[/sub]) atmosphere "freezes out" during the winter in the northern and southern hemispheres. The south polar cap is higher in altitude and colder than the one in the north.
The residual southern ice cap is displaced; that is, it is not centered on the south pole. Studies have shown that the off center cap is caused by much more snow falling on one side than the other. On the western hemisphere side of the south pole a low pressure system forms because the winds are changed by the Hellas Basin. This system produces more snow. On the other side, there is less snow and more frost. Snow tends to reflect more sunlight in the summer, so not much melts or sublimates. Frost, on the other hand has a rougher surface and tends to trap more sunlight, resulting in more sublimation.
Research, published in April 2011, described a large deposit of frozen carbon dioxide near the south pole. Most of this deposit probably enters Mars' atmosphere when the planet's tilt increases. When this occurs, the atmosphere thickens, winds get stronger, and larger areas on the surface can support liquid water. Analysis of data showed that if these deposits were all changed into gas, the atmospheric pressure on Mars would double. There are three layers of these deposits; each is capped with a 30-meter layer of water ice that prevents the CO2 from sublimating into the atmosphere. In sublimation a solid material goes directly into a gas phase. These three layers are linked to periods when the atmosphere collapsed when the climate changed.>>[/quote][quote=Popeye post_id=284614 time=1533139793]
[list]Looks like Pluto[/list][/quote][quote=" https://en.wikipedia.org/wiki/Sputnik_Planitia"]
[float=left][img3="No craters = Sputnik Planitia less than 10 million years old"]https://upload.wikimedia.org/wikipedia/commons/2/21/PIA20154-Pluto-MapOfOver1000Craters-20151110.jpg[/img3][/float]
<<The informal name Sputnik Planum was first announced by the New Horizons team on a press conference on 24 July 2015. A planum is a flat region of higher elevation (a plateau). When topographical data was analyzed in early 2016, it became clear that Sputnik is actually a basin, and the informal name was changed to Sputnik Planitia. [b][u][color=#0000FF]Sputnik Planitia is presently close to the anti-Charon point on Pluto[/color][/u][/b], a result that has less than a 5% probability of arising by chance. Sputnik Planitia, the western lobe of the "Heart", is a 1,000 km-wide basin of frozen nitrogen and carbon monoxide ices, divided into polygonal cells, which are interpreted as convection cells that carry floating blocks of water ice crust and sublimation pits towards their margins; there are obvious signs of glacial flows both into and out of the basin. It has no craters that were visible to New Horizons, indicating that its surface is less than 10 million years old.
A high seasonal thermal inertia of Pluto's surface is an important driver of deposition of nitrogen ice at low latitudes. These latitudes receive less annual insolation than Pluto's polar regions due to its high obliquity (122.5°). [b][color=#0000FF][u]The coldest regions on Pluto, on average, are at 30° N.[/u] and S. latitude[/color][/b]; early in Pluto's history, ice would tend to accumulate at these latitudes in a runaway process due to the positive feedback association of increased albedo, cooling and further ice deposition (similar to the ice segregation that occurred on Iapetus). Simulations suggest that over a period of about a million years, the runaway process would collect much of the ice into a single cap even in the absence of a preexisting basin.>>[/quote]