Talk:Atmospheric escape

Article requires cleanup

It should be edited I think. It clearly sounds like it is take from the middle of a book with references to some Tables which are not there. Also, it is not well written for an encyclopedia. For instance, the Jean escape term is used all over, yet it is mentioned very insiginificantly that Jean escape and thermal escape is the same thing. —Preceding unsigned comment added by Louigi Verona (talk • contribs) 16:33, 20 November 2007 (UTC)

I agree. At the bottom are 'sources'. That isn't the Wikipedia format. Youre supposed to cite the work then at the bottom type '{{Reflist}}' Vinson (talk) 01:29, 22 May 2008 (UTC)

Example: The Three Little Pigs are brothers

Missing escape processes

The article is missing some escape processes.

• Hydrodynamic escape
• Nonthermal ecape
• Polar wind escape
• Homopause Effect
• Sputtering

The first four should probably be made into redirects once they are added to the article. There is already an article at sputtering. -- Kjkolb 15:00, 29 April 2006 (UTC)

The article doesn't mention exoplanets, which can lose mass very differently (Murray-Clay et al., 2009 Astrophysical Journal 693:23–42, 2009 March 1)

Venus receives more solar radiation and is hotter, not lower gravity

Venus is not much less massive than the earth, so its loss of water may be due to that it receives more solar energy. I suggest that only "Mars" be listed as having lost water due to lower gravity. Anyone with better data? — Preceding unsigned comment added by Astropro (talk • contribs) 14:34, 21 August 2011 (UTC)

evaporation of oceans

I deleted the following text, under "blow off", from the section on thermal escape: "[blow-off] might possibly be a way for Venus to lose its water early in its history. It is closer to the Sun than the Earth so that early in its history its oceans probably boiled off. Assuming it started with a similar amount of water to Earth, evaporating all its water would lead to an atmosphere with a pressure of 270 bars (the surface of the Earth is at 1 bar) composed almost entirely of super-heated steam."

I'm not sure quite what the relevance is here. Evaporation of the ocean is not the same as escape. Although the first step in getting the water to escape is clearly getting it into the atmosphere, the escape process is different from the evaporation. The surface pressure of 270 bars is irrelevant, since the atmosphere doesn't escape from the surface-- the text seemed to imply that the "tremendous" pressure of 270 bars would cause the atmosphere to just blow off into space, but this is not true-- that 270 bars is actually the pressure downward on the atmosphere, where the gas above the surface holds the gas at the surface down.

It might be desirable to delete the whole "blow off" text, since I don't think it's very clear, and I'm not sure what it has to do with thermal escape. Geoffrey.landis 15:53, 23 March 2007 (UTC)

Sourced nonthermal escape section

I edited the article to include all the major nonthermal processes, with scientific journal references. It's bulky, but it all fits into the concept of atmospheric escape. I don't know how to properly attribute the tables with titles and source underneath them, if someone could take care of that, or tell me how to do it, I would feel less bad about reproducing them without citation. It also needs to be cross-referenced throughout. Rendence 20:32, 19 May 2007 (UTC)

Atmospheric_escape#Significance_of_Solar_Winds

Hi, I don't want to alter something that I don't understand or have good reference for. If it is of any use I will list some difficulties in the first paragraph of the section in case anyone can improve -

• "The relative importance of each loss process is a function ..." That is very difficult

• "Most people erroneously think that the primary non-thermal escape mechanism is atmospheric stripping by a solar wind in the absence of a magnetic field. Excess kinetic energy from solar winds can impart sufficient energy into atmospheric particles to reach escape velocity, causing atmospheric escape." Appears to be contradictory

~ R.T.G 22:23, 20 November 2009 (UTC)

I think there is a contradiction as well. The Lammar article is here (http://www.sciencedirect.com/science/article/pii/S003206330600170X), but another Wikipedia article (http://en.wikipedia.org/wiki/Atmosphere_of_Venus#Induced_magnetosphere) currently states the following:

"Due to the lack of the intrinsic magnetic field on Venus, the solar wind penetrates relatively deep into the planetary exosphere and causes substantial atmosphere loss.[31] The loss happens mainly via the magnetotail. Currently the main ion types being lost are O+, H+ and He+. The ratio of hydrogen to oxygen losses is around 2 (i.e. almost stoichiometric) indicating the ongoing loss of water.[30]"

The citations are from a NASA article (http://sunearth.gsfc.nasa.gov/sunearthday/2004/vt_venus_planetary_2004.htm) and a 2007 issue of Nature (http://www.nature.com/nature/journal/v450/n7170/full/nature06434.html). It's also confusing to say "Recent models indicate that stripping by solar wind accounts for less than 1/3 of total non-thermal loss processes.[3]" Would it be more helpful to give a comparison of thermal losses vs. non-thermal losses for Mars and Venus? I'm not an expert in this and I hope someone will weigh in here.Nydoc1 (talk) 08:38, 12 February 2013 (UTC)Nydoc1

Non-thermal Escape

The citation for the hydrodynamic "blow-off" is Watson, Donahue, Walker (Icarus 48, 150-166, 1981). They derive a solution similar to the solar wind solution (Parker 1963). In the thermosphere hydrogen escapes rapidly in a hydrodynamic bulk flow induced by heating through solar EUV radiation. This flow might be restricted by diffusion of hydrogen throught the lower atmospheric layers. Havier atoms may be washed out of the atmosphere if the escape velocity is larger than the diffusion velocity of the atoms downwards. They are just carried along. Note, that the process happens in the heterosphere, where the atmosphere is no longer a mix of different molecules, but consist mainly of hydrogen. It is believed to be an ongoing process on hot Jupiters like HD 209458b, Vidal-Madjar et al., Nature, Volume 422, Issue 6928, pp. 143-146 (2003).

Sorry, this is my first edit, so I post it here in the discussion, so that somebody who is more familiar with wikipedia can change the article, if necessary.

85.183.206.138 (talk) 09:11, 15 April 2011 (UTC)

Possible Wikiversity contribution

I am developing teaching materials for college level astronomy on Wikipedia and am contemplating the inclusion of the following link into this article. Although the page is very much "under construction", it is clearly not going to be suitable as a Wikipedia article. When the calculation is complete, I would like to include it in this article as a link that would look something like this:

• See also Why planets lose their atmospheres (Wikiversity)

--guyvan52 (talk) 19:40, 21 February 2014 (UTC)

Link to wikiversity article

I am a college professor attempting to use Wikipedia to construct a college course in Astronomy and found this article helpful. I copied and edited portions, elaborated in some places, and referenced this article. If the watchers of this page don't like the link there will be no hard feelings.--guyvan52 (talk) 02:01, 23 February 2014 (UTC)

Needs a rewrite. (Sept 2014)

This article is really bad. The lede is almost useless and the first section Thermal Escape Mechanisms is VERY poorly written. Whoever wrote this has apparently not been exposed to the idea of an "introduction". I've changed the claim that increasing temperature moves the range of velocities in the distribution 'upwards', how lame is that? It claims that "THE" reason Jupiter retains hydrogen is its size...apparently its location and age have nothing to do with it??? Wrong. Similarly the claim that Titan is cooler ("colder than what?" is left to the reader's imagination) and hence retains its atmosphere is made. Wow. These are Middle School mistakes! Also, if Jeans escape is one type of thermal escape, then why in the world would you immediately launch into a description of it without any context? Poor, poor, poor. I was on my second correction to the article when I realized the job was bigger than I now have time for. Looking for a few good men and women here... Atmosphere can escape due to its temperature (velocity), due to the solar wind, due to collision and near collisions with massive objects (comets, asteroids), due to gravitation of near-by bodies and due to electrical charge effects. DON'T use the word sun, use Sun if you mean our star, but generically use star (and stellar wind). I should add that the entire article is disjointed almost to the point of unintelligibility. 173.189.74.95 (talk) 00:12, 16 September 2014 (UTC)