Editing Solar System (section)

=== Composition ===
{{Further|List of Solar System objects|List of interstellar and circumstellar molecules}}

The principal component of the Solar System is the Sun, a [[G-type main-sequence star]] that contains 99.86% of the system's known mass and dominates it gravitationally.<ref>{{Cite journal |last=Woolfson |first=M. |date=2000 |title=The origin and evolution of the solar system |journal=[[Astronomy & Geophysics]] |volume=41 |issue=1 |pages=1.12–1.19 |bibcode=2000A&G....41a..12W |doi=10.1046/j.1468-4004.2000.00012.x |doi-access=free}}</ref> The Sun's four largest orbiting bodies, the giant planets, account for 99% of the remaining mass, with Jupiter and Saturn together comprising more than 90%. The remaining objects of the Solar System (including the four terrestrial planets, the dwarf planets, moons, [[asteroid]]s, and comets) together comprise less than 0.002% of the Solar System's total mass.{{Refn |The mass of the Solar System excluding the Sun, Jupiter and Saturn can be determined by adding together all the calculated masses for its largest objects and using rough calculations for the masses of the Oort cloud (estimated at roughly 3 Earth masses),<ref>{{Cite arXiv |eprint=astro-ph/0512256 |first=Alessandro |last=Morbidelli |title=Origin and dynamical evolution of comets and their reservoirs |date=2005}}</ref> the Kuiper belt (estimated at 0.1 Earth mass)<ref name="Delsanti-Beyond_The_Planets"/> and the asteroid belt (estimated to be 0.0005 Earth mass)<ref name="Krasinsky2002"/> for a total, rounded upwards, of ~37 Earth masses, or 8.1% of the mass in orbit around the Sun. With the combined masses of Uranus and Neptune (~31 Earth masses) subtracted, the remaining ~6 Earth masses of material comprise 1.3% of the total orbiting mass.|name=footnoteD|group=lower-alpha}}

The Sun is composed of roughly 98% hydrogen and helium,<ref>{{Cite web |title=The Sun's Vital Statistics |url=http://solar-center.stanford.edu/vitalstats.html |url-status=live |archive-url=https://www.webcitation.org/6BOkQXma3?url=http://solar-center.stanford.edu/vitalstats.html |archive-date=14 October 2012 |access-date=29 July 2008 |publisher=Stanford Solar Center |postscript=,}} citing {{Cite book
|last=Eddy
|first=J.
|title=A New Sun: The Solar Results From Skylab
|url=https://history.nasa.gov/SP-402/contents.htm
|publisher=[[NASA]]
|date=1979
|page=37
|id=NASA SP-402
|access-date=12 July 2017
|archive-date=30 July 2021
|archive-url=https://web.archive.org/web/20210730024856/https://history.nasa.gov/SP-402/contents.htm
|url-status=live
}}</ref> as are Jupiter and Saturn.<ref>{{Cite web |last=Williams |first=David R. |date=7 September 2006 |title=Saturn Fact Sheet |url=http://nssdc.gsfc.nasa.gov/planetary/factsheet/saturnfact.html |url-status=dead |archive-url=https://web.archive.org/web/20110804224236/http://nssdc.gsfc.nasa.gov/planetary/factsheet/saturnfact.html |archive-date=4 August 2011 |access-date=31 July 2007 |publisher=NASA }}</ref><ref name="Williams-Jupiter" /> A composition gradient exists in the Solar System, created by heat and [[light pressure]] from the early Sun; those objects closer to the Sun, which are more affected by heat and light pressure, are composed of elements with high melting points. Objects farther from the Sun are composed largely of materials with lower melting points.<ref>{{Cite book |last1=Weissman |first1=Paul Robert |url=https://archive.org/details/encyclopediaofso0000unse_u6d1/page/615 |title=Encyclopedia of the solar system |last2=Johnson |first2=Torrence V. |date=2007 |publisher=Academic Press |isbn=978-0-12-088589-3 |page=[https://archive.org/details/encyclopediaofso0000unse_u6d1/page/615 615]}}</ref> The boundary in the Solar System beyond which those volatile substances could coalesce is known as the [[Frost line (astrophysics)|frost line]], and it lies at roughly five times the Earth's distance from the Sun.<ref name="Mumma" />