Editing Neutron star (section)

===Density and pressure===
[[File:White dwarf vs neutron star.svg|thumb|right|Comparison of a 10 km radius neutron star (top left corner) and a 6000 km radius [[white dwarf]], the latter roughly the size of [[Earth]].]]
Neutron stars have overall densities of {{val|3.7|e=17}} to {{val|5.9|e=17|u=kg/m3}} ({{val|2.6|e=14}} to {{val|4.1|e=14}} times the density of the Sun),<ref group="lower-alpha">{{val|3.7|e=17|u=kg/m3}} derives from mass {{val|2.68|e=30|u=kg}} / volume of star of radius 12&nbsp;km; {{val|5.9|e=17|u=kg/m3}} derives from mass {{val|4.2|e=30|u=kg}} per volume of star radius 11.9&nbsp;km</ref> which is comparable to the approximate density of an atomic nucleus of {{val|3|e=17|u=kg/m3}}.<ref>{{cite web |url=http://heasarc.gsfc.nasa.gov/docs/xte/learning_center/ASM/ns.html |title=Calculating a Neutron Star's Density |access-date=2006-03-11 |archive-date=2006-02-24 |archive-url=https://web.archive.org/web/20060224011955/http://heasarc.gsfc.nasa.gov/docs/xte/learning_center/ASM/ns.html |url-status=live }} NB {{val|3|e=17|u=kg/m3}} is {{val|3|e=14|u=g/cm3}}</ref> The density increases with depth, varying from about {{val|1|e=9|u=kg/m3}} at the crust to an estimated {{val|6|e=17}} or {{val|8|e=17|u=kg/m3}} deeper inside.<ref name="Miller">{{cite journal |title=Introduction to neutron stars |journal=American Institute of Physics Conference Series |volume=1645 |issue=1 |pages=61–78 |bibcode=2015AIPC.1645...61L |last1=Lattimer |first1=James M. |year=2015 |doi=10.1063/1.4909560 |series=AIP Conference Proceedings |doi-access=free }}</ref> Pressure increases accordingly, from about {{val|3.2|u=Pa|e=31}} (32&nbsp;[[quetta-|Q]]Pa) at the inner crust to {{val|1.6|e=34|u=Pa}} in the center.<ref>{{Cite journal |last1=Ozel |first1=Feryal |last2=Freire |first2=Paulo |title=Masses, Radii, and the Equation of State of Neutron Stars |journal=Annu. Rev. Astron. Astrophys. |volume=54 |issue=1 |pages=401–440 |date=2016 |doi=10.1146/annurev-astro-081915-023322 |bibcode=2016ARA&A..54..401O |arxiv = 1603.02698 |s2cid=119226325 }}</ref>

A neutron star is so dense that one teaspoon (5 [[milliliter]]s) of its material would have a mass over {{val|5.5|e=12|u=kg}}, about 900 times the mass of the [[Great Pyramid of Giza]].<ref group="lower-alpha">The average density of material in a neutron star of radius 10&nbsp;km is {{val|1.1|e=12|u=kg/cm3}}. Therefore, 5&nbsp;ml of such material is {{val|5.5|e=12|u=kg}}, or 5,500,000,000 [[metric ton]]s. This is about 15 times the total mass of the human world population. Alternatively, 5&nbsp;ml from a neutron star of radius 20&nbsp;km radius (average density {{val|8.35|e=10|u=kg/cm3}}) has a mass of about 400 million metric tons, or about the mass of all humans. The gravitational field is ca. {{val|2|e=11}}''g'' or ca. {{val|2|e=12}} N/kg. Moon weight is calculated at 1''g''.</ref> The entire mass of the Earth at neutron star density would fit into a sphere 305&nbsp;m in diameter, about the size of the [[Arecibo Telescope]].

In popular scientific writing, neutron stars are sometimes described as macroscopic [[atomic nucleus|atomic nuclei]]. Indeed, both states are composed of [[nucleon]]s, and they share a similar density to within an order of magnitude. However, in other respects, neutron stars and atomic nuclei are quite different. A nucleus is held together by the [[strong interaction]], whereas a neutron star is held together by [[gravity]]. The density of a nucleus is uniform, while neutron stars are [[#Structure|predicted to consist of multiple layers]] with varying compositions and densities.<ref>{{Cite journal |last1=Baym |first1=G |last2=Pethick |first2=C |date=December 1975 |title=Neutron Stars |journal=Annual Review of Nuclear Science |language=en |volume=25 |issue=1 |pages=27–77 |doi=10.1146/annurev.ns.25.120175.000331 |issn=0066-4243 |bibcode=1975ARNPS..25...27B |doi-access=free }}</ref>