# Is there a consensus as to where terrrestrial planet atmospheres in our solar system came from?

I tried to research this and I'm not sure if there is a consensus where the $CO_2$, $N_2$, etc. comes from on terrestrial planets like Venus, Earth and Mars. Possible sources would be accretion from the protoplanetary disk, outgassing (which I would think would require plate tectonics/ molten core) or reactions at the surface caused by stellar radiation. Also, reactions in the atmosphere can alter the composition. Would it be a combination of all of the above and, if so, do we know if one of the processes dominated over the others? Does anybody have a good link that discusses this?

• also impacts from asteroids and comets Oct 15 '16 at 16:53
• @Zephyr .. I went ahead and put this in as a question as advised. It may belong more in the Earth Sciences stack exchange, but I think it is relevant here, too. Oct 15 '16 at 16:56
• great question! Oct 16 '16 at 20:55
• A quite recent study about the origin and development of terrestrial planet atmospheres is the 2015 paper "The Atmospheres of the Terrestrial Planets: Clues to the Origins and Early Evolution of Venus, Earth, and Mars" (Baines et al.) includes a fairly comprehensive analysis of chemical evidence from Earth and from Martian meteorites and observations of the atmosphere of Venus.
– user15217
Dec 22 '16 at 4:27
• @comprehensible: "The pre-planetary disk would have been centrifugally sorted." Is a wrong statement. The centrifugal force is balanced by gravity in radial direction in a PP-disc, so there is no sorting in that direction. In altitude above the disc midplane, sedimentation by particle sizes will work, but not sorting by mass. May 1 '17 at 20:49