Obliquity Variability of a Potentially Habitable Early Venus.
Venus currently rotates slowly, with its spin controlled by solid-body and atmospheric thermal tides. However, conditions may have been far different 4 billion years ago, when the Sun was fainter and most of the carbon within Venus could have been in solid form, implying a low-mass atmosphere. We investigate how the obliquity would have varied for a hypothetical rapidly rotating Early Venus. The obliquity variation structure of an ensemble of hypothetical Early Venuses is simpler than that Earth would have if it lacked its large moon (Lissauer et al., 2012 ), having just one primary chaotic regime at high prograde obliquities. We note an unexpected long-term variability of up to ±7° for retrograde Venuses. Low-obliquity Venuses show very low total obliquity variability over billion-year timescales-comparable to that of the real Moon-influenced Earth.



Planets and satellites-Venus. Astrobiology 16, 487-499.
1 Department of Physics, University of Idaho , Moscow, Idaho. Researcher ID: B-1284-2009.
Jason W
JW
Barnes
2 Space Science and Astrobiology Division, NASA Ames Research Center , Moffett Field, California.|3 Department of Physics and Physical Science, The University of Nebraska at Kearney , Kearney, Nebraska.
Billy
B
Quarles
2 Space Science and Astrobiology Division, NASA Ames Research Center , Moffett Field, California.
Jack J
JJ
Lissauer
4 Department of Terrestrial Magnetism, Carnegie Institution of Washington , Washington, DC.
John
J
Chambers
1 Department of Physics, University of Idaho , Moscow, Idaho. Researcher ID: B-1284-2009.
Matthew M
MM
Hedman
D055580:Astronomical Phenomena; D001272:Atmosphere / Q000737:chemistry; D002980:Climate; D018559:Exobiology; D005118:Extraterrestrial Environment / Q000737:chemistry; D055641:Mathematical Concepts; D016082:Solar System; D018536:Venus