Editing Astronomy (section)

=== Astrophysics ===
{{main |Astrophysics}}
[[File:Observable Universe logarithmic illustration (circular layout english annotations).png|thumb|Astrophysics applies [[physics]] and [[chemistry]] to understand the measurements made by astronomy. Representation of the Observable Universe that includes images from [[Hubble Space Telescope|Hubble]] and other [[List of optical telescopes|telescopes]].]]

Astrophysics is the branch of astronomy that employs the principles of physics and [[chemistry]] "to ascertain the nature of the [[astronomical object]]s, rather than their positions or motions in space".<ref>{{Cite journal | last = Keeler | first = James E. | author-link = James E. Keeler | title = The Importance of Astrophysical Research and the Relation of Astrophysics to the Other Physical Sciences | journal = The Astrophysical Journal | volume = 6 | issue = 4 | pages = 271–88 | date = November 1897 | bibcode = 1897ApJ.....6..271K |doi = 10.1086/140401| pmid = 17796068 | quote =[Astrophysics] is closely allied on the one hand to astronomy, of which it may properly be classed as a branch, and on the other hand to chemistry and physics.... It seeks to ascertain the nature of the heavenly bodies, rather than their positions or motions in space—''what'' they are, rather than ''where'' they are.... That which is perhaps most characteristic of astrophysics is the special prominence which it gives to the study of radiation.| doi-access = free }}</ref><ref>{{cite web | title=astrophysics | publisher=Merriam-Webster, Incorporated | url=http://www.merriam-webster.com/dictionary/astrophysics | access-date=22 May 2011 | archive-url= https://web.archive.org/web/20110610085146/http://www.merriam-webster.com/dictionary/astrophysics| archive-date= 10 June 2011 | url-status= live}}</ref> Among the objects studied are the [[Sun]], other [[star]]s, [[galaxy|galaxies]], [[extrasolar planet]]s, the [[interstellar medium]] and the [[cosmic microwave background]].<ref name="nasa.gov">{{cite web|url=https://science.nasa.gov/astrophysics/focus-areas/|title=Focus Areas – NASA Science|work=nasa.gov|access-date=12 November 2018|archive-date=16 May 2017|archive-url=https://web.archive.org/web/20170516154030/https://science.nasa.gov/astrophysics/focus-areas|url-status=live}}</ref><ref>{{cite encyclopedia|url=https://www.britannica.com/EBchecked/topic/40047/astronomy|title=astronomy|encyclopedia=Encyclopædia Britannica|access-date=12 November 2018|archive-date=10 May 2015|archive-url=https://web.archive.org/web/20150510024116/https://www.britannica.com/EBchecked/topic/40047/astronomy|url-status=live}}</ref> Their emissions are examined across all parts of the [[electromagnetic spectrum]], and the properties examined include [[luminosity]], [[density]], [[temperature]], and [[chemistry|chemical]] composition. Because astrophysics is a very broad subject, ''astrophysicists'' typically apply many disciplines of physics, including [[mechanics]], [[electromagnetism]], [[statistical mechanics]], [[thermodynamics]], [[quantum mechanics]], [[theory of relativity|relativity]], [[nuclear physics|nuclear]] and [[particle physics]], and [[atomic, molecular, and optical physics|atomic and molecular physics]].{{cn|date=March 2025}}

In practice, modern astronomical research often involves a substantial amount of work in the realms of [[Theoretical physics|theoretical]] and observational physics. Some areas of study for astrophysicists include their attempts to determine the properties of [[dark matter]], [[dark energy]], and [[black holes]]; whether or not [[time travel]] is possible, [[wormhole]]s can form, or the [[multiverse]] exists; and the [[Cosmogony|origin]] and [[ultimate fate of the universe]].<ref name="nasa.gov"/> Topics also studied by theoretical astrophysicists include [[Formation and evolution of the Solar System|Solar System formation and evolution]]; [[stellar dynamics]] and [[Stellar evolution|evolution]]; [[galaxy formation and evolution]]; [[magnetohydrodynamics]]; [[large-scale structure of the universe|large-scale structure]] of [[matter]] in the universe; origin of [[cosmic ray]]s; [[general relativity]] and [[physical cosmology]], including [[string theory|string]] cosmology and [[astroparticle physics]].{{cn|date=March 2025}}