Random synapses firing reading across posted questions here on SEx.SE ...

  1. Martian gravity is weaker than Terran
  2. Martian magnetic field almost non-existent
  3. Martian atmosphere is far thinner than Terran
  4. Traces of water/moisture were reportedly discovered on Mars

Facts as I understand

  • A magnetic field helps retard the impact of Sunspots/CME, and contain the atmosphere of a planet/body.
  • Above is assisted by the planet's gravity

From the above, and knowing what we do about Mars at present ...

  • How would the nature of the Martian atmosphere, in it's heyday, differ from Earth by virtue (or vice!) of the weaker planetary gravity?
  • Could the Martian atmosphere, in it's heyday, have caused liquid water in oceanic/sub-oceanic volumes?
  • 1
    $\begingroup$ By "sub-oceanic volume" do you mean smaller than an ocean, such as lake-sized or pond-sized? $\endgroup$ Jan 17, 2015 at 5:15
  • 1
    $\begingroup$ @JerardPuckett Smaller than an ocean but perhaps not so small as a pond, or vast shallow-depth expanse if a pond... ugh. that comes across as so contradictory $\endgroup$
    – Everyone
    Jan 17, 2015 at 7:01

1 Answer 1


It's not yet proven, and other explanations are still possible, but evidence for a paleo-ocean in Mars's northern hemisphere has been mounting for the past several decades.

From Wikipedia:

Research published in 2009 shows a much higher density of stream channels than formerly believed. Regions on Mars with the most valleys are comparable to what is found on the Earth. In the research, the team developed a computer program to identify valleys by searching for U-shaped structures in topographical data. The large amount of valley networks strongly supports rain on the planet in the past. The global pattern of the Martian valleys could be explained with a big northern ocean. A large ocean in the northern hemisphere would explain why there is a southern limit to valley networks; the southernmost regions of Mars, farthest from the water reservoir, would get little rainfall and would develop no valleys. In a similar fashion the lack of rainfall would explain why Martian valleys become shallower from north to south.

A 2010 study of deltas on Mars revealed that seventeen of them are found at the altitude of a proposed shoreline for a Martian ocean. This is what would be expected if the deltas were all next to a large body of water.


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