Editing Polar ice cap (section)

==Mars==
{{main|Martian polar ice caps|Planum Australe|Planum Boreum}}
[[File:Mars NPArea-PIA00161.jpg|thumb|[[Mars]]'s north polar region with ice cap, composite of [[Viking 1]] orbiter images (Courtesy [[NASA]]/[[JPL]]-Caltech)]]
In addition to Earth, the planet [[Mars]] also has polar ice caps.  They consist of primarily water-ice with a few percent dust.<ref>{{cite journal |title=North polar deposits of Mars: Extreme purity of the water ice |author1=Grima, Cyril G. |author2=Kofman, W. |author3=Mouginot, J. |author4=Phillips, R. J. |author5=Herique, A. |author6=Biccardi, D. |author7=Seu, R. |author8=Cutigni, M. |journal=Geophysical Research Letters |volume=36 |year=2009 |url=http://www.agu.org/pubs/crossref/2009/2008GL036326.shtml |archive-url=https://archive.today/20120717081531/http://www.agu.org/pubs/crossref/2009/2008GL036326.shtml |url-status=dead |archive-date=17 July 2012 |doi=10.1029/2008GL036326 |issue=3 |pages=n/a |bibcode=2009GeoRL..36.3203G |s2cid=129096278 }}</ref>  Frozen carbon dioxide makes up a small permanent portion of the [[Planum Australe]] or the South Polar Layered Deposits.  In both hemispheres a seasonal [[carbon dioxide]] frost deposits in the winter and [[sublimation (physics)|sublimates]] during the spring.{{citation needed|date=May 2020}}

Data collected in 2001 from NASA missions to Mars show that the southern residual ice cap undergoes sublimation inter-annually.  The most widely accepted explanation is that fluctuations in the planet's orbit are causing the changes.<ref>{{cite web | url=http://news.nationalgeographic.com/news/2007/02/070228-mars-warming.html | archive-url=https://web.archive.org/web/20070302094717/http://news.nationalgeographic.com/news/2007/02/070228-mars-warming.html | url-status=dead | archive-date=2 March 2007 | title=Mars Melt Hints at Solar, Not Human, Cause for Warming, Scientist Says | first=Kate | last=Ravilious | work=[[National Geographic News]] | publisher=[[National Geographic Society]] | date=28 February 2007 | access-date=28 October 2008 }}</ref>