Editing Neon (section)

==Occurrence==
Stable isotopes of neon are produced in stars. Neon's most abundant isotope <sup>20</sup>Ne (90.48%) is created by the [[nuclear fusion]] of [[carbon]] and carbon in the [[carbon-burning process]] of [[stellar nucleosynthesis]]. This requires temperatures above 500 [[megakelvin]]s, which occur in the cores of stars of more than 8 solar masses.<ref>{{Cite book|url=https://books.google.com/books?id=fXcdHyLUVnEC&q=neon+cosmic+nucleosynthesis&pg=PA106|title=Handbook of Isotopes in the Cosmos: Hydrogen to Gallium|last=Clayton|first=Donald|publisher=Cambridge University Press|year=2003|isbn=978-0521823814|pages=106–107}}</ref><ref>{{cite book|author1=Ryan, Sean G. |author2=Norton, Andrew J. | title=Stellar Evolution and Nucleosynthesis | year=2010 | page=135| isbn=978-0-521-13320-3|publisher=[[Cambridge University Press]]|url=https://books.google.com/books?id=PE4yGiU-JyEC&q=carbong+burning}}</ref>

Neon is abundant on a universal scale; it is the [[Abundance of the chemical elements|fifth most abundant chemical element]] in the universe by mass, after hydrogen, helium, oxygen, and carbon (see [[chemical element]]).<ref>{{cite journal |bibcode=2009ARA&A..47..481A |doi=10.1146/annurev.astro.46.060407.145222 |title=The Chemical Composition of the Sun |journal=Annual Review of Astronomy and Astrophysics |volume=47 |issue=1 |pages=481–522 |year=2009 |last1=Asplund |first1=Martin |last2=Grevesse |first2=Nicolas |last3=Sauval |first3=A. Jacques |last4=Scott |first4=Pat |arxiv=0909.0948|s2cid=17921922 }}</ref> Its relative rarity on Earth, like that of helium, is due to its relative lightness, high vapor pressure at very low temperatures, and chemical inertness, all properties which tend to keep it from being trapped in the condensing gas and dust clouds that formed the smaller and warmer solid planets like Earth. 
Neon is monatomic, making it lighter than the molecules of diatomic nitrogen and oxygen which form the bulk of Earth's atmosphere; a balloon filled with neon will rise in air, albeit more slowly than a helium balloon.<ref>{{cite book |title = Chemistry for Higher Tier |author = Gallagher, R. |author2 = Ingram, P. |publisher = University Press |isbn = 978-0-19-914817-2 |url = https://books.google.com/books?id=SJtWSy69eVsC&pg=PA96 |pages = 282 |date = 19 July 2001}}</ref>

Neon's abundance in the universe is about 1 part in 750 by mass; in the Sun and presumably in its proto-solar system nebula, about 1 part in 600.{{citation needed|date=December 2023}} The [[Galileo spacecraft]] atmospheric entry probe found that in the upper atmosphere of Jupiter, the abundance of neon is reduced (depleted) by about a factor of 10, to a level of 1 part in 6,000 by mass. This may indicate that the ice-[[planetesimal]]s that brought neon into Jupiter from the outer solar system formed in a region that was too warm to retain the neon atmospheric component (abundances of heavier inert gases on Jupiter are several times that found in the Sun),<ref>{{cite web |url=http://www2.jpl.nasa.gov/sl9/gll38.html |title=Galileo Probe Science Result |access-date=27 February 2007 |last=Morse |first=David |date=26 January 1996 |publisher=Galileo Project |url-status=live |archive-url=https://web.archive.org/web/20070224232055/http://www2.jpl.nasa.gov/sl9/gll38.html |archive-date=24 February 2007 }}</ref> or that neon is selectively sequestered in the planet's interior.<ref name="Wilson2010">{{citation | title=Sequestration of Noble Gases in Giant Planet Interiors | last1=Wilson | first1=Hugh F. | last2=Militzer | first2=Burkhard | journal=Physical Review Letters | volume=104 | issue=12 | pages=121101 | id=121101 | date=March 2010 | doi=10.1103/PhysRevLett.104.121101 | pmid=20366523 | bibcode=2010PhRvL.104l1101W | arxiv=1003.5940 | s2cid=9850759 | postscript=. }}</ref>

Neon comprises 1 part in 55,000 in the [[Earth's atmosphere]], or 18.2&nbsp;ppm by volume (this is about the same as the molecule or mole fraction), or 1 part in 79,000 of air by mass. It comprises a smaller fraction in the crust. It is industrially produced by cryogenic [[fractional distillation]] of liquefied air.<ref name="CRC" />

On 17 August 2015, based on studies with the [[Lunar Atmosphere and Dust Environment Explorer]] (LADEE) spacecraft, NASA scientists reported the detection of neon in the [[exosphere]] of the [[moon]].<ref name="NASA-20150817">{{cite web |last=Steigerwald |first=William |title=NASA's LADEE Spacecraft Finds Neon in Lunar Atmosphere |url=http://www.nasa.gov/content/goddard/ladee-lunar-neon |date=17 August 2015 |work=[[NASA]] |access-date=18 August 2015 |url-status=live |archive-url=https://web.archive.org/web/20150819035151/http://www.nasa.gov/content/goddard/ladee-lunar-neon/ |archive-date=19 August 2015 }}</ref>