Editing Crab Nebula (section)

===Connection to SN 1054===
[[File:A whole new view of the Crab Nebula.jpg|thumb|The nebula is seen in the visible spectrum at 550&nbsp;nm (green light).]]

The Crab Nebula was the first astronomical object recognized as being connected to a supernova explosion.<ref name="Mayall"/> In the early twentieth century, the analysis of early [[astrophotography|photographs]] of the nebula taken several years apart revealed that it was expanding. Tracing the expansion back revealed that the nebula must have become visible on Earth about 900&nbsp;years before. Historical records revealed that a new star bright enough to be seen in the daytime had been recorded in the same part of the sky by Chinese astronomers on 4 July 1054, and probably also by Japanese observers.<ref name="Mayall">{{cite journal |last=Mayall |first=Nicholas Ulrich |author-link=Nicholas Mayall |title=The Crab Nebula, a Probable Supernova |journal=[[Astronomical Society of the Pacific Leaflets]] |volume=3 |issue=119 |page=145 |date=1939 |bibcode=1939ASPL....3..145M}}</ref><ref>{{Cite book |last=Leverington |first=David |url=https://books.google.com/books?id=r47qBwAAQBAJ |title=A History of Astronomy: from 1890 to the Present |publisher=Springer Science & Business Media |year=2012 |isbn=978-1-4471-2124-4 |page=197 |language=en}}</ref><ref name="Lundmark">{{cite journal |last=Lundmark |first=Knut |author-link=Knut Lundmark |title=Suspected New Stars Recorded in Old Chronicles and Among Recent Meridian Observations |journal=[[Publications of the Astronomical Society of the Pacific]] |volume=33 |issue=195 |pages=225–238 |date=1921 |bibcode=1921PASP...33..225L |jstor=40668518 |doi=10.1086/123101|s2cid=120275870 |url=https://zenodo.org/record/1431279 }}</ref>

In 1913, when [[Vesto Slipher]] registered his [[spectroscopy]] study of the sky, the Crab Nebula was again one of the first objects to be studied. Changes in the cloud, suggesting its small extent, were discovered by [[Carl Lampland]] in 1921.<ref name=lampland>{{cite journal |title=Observed Changes in the Structure of the "Crab" Nebula (N. G. C. 1952) |journal=[[Publications of the Astronomical Society of the Pacific]] |last=Lampland |first=C. O. |author-link=Carl Otto Lampland |volume=33 |issue=192 |pages=79–84 |date=1921 |bibcode=1921PASP...33...79L |jstor=40710638 <!--|alternate url=https://archive.org/details/jstor-40710638--> |doi=10.1086/123039|s2cid=122115955 }}</ref> That same year, [[John Charles Duncan]] demonstrated that the remnant was expanding,<ref name=duncan>{{cite journal |last=Duncan |first=John Charles |title=Changes Observed in the Crab Nebula in Taurus |journal=[[Proceedings of the National Academy of Sciences]] |volume=7 |issue=6 |pages=179–181 |date=1921 |bibcode=1921PNAS....7..179D |doi=10.1073/pnas.7.6.179 |pmid=16586833 |pmc=1084821|doi-access=free }}</ref> while [[Knut Lundmark]] noted its proximity to the guest star of 1054.<ref name="Lundmark"/><ref name=Srinivasan1997>{{cite book |last=Srinivasan |first=G. |chapter=Neutron Stars |title=Stellar Remnants |publisher=Springer Science |series=Lecture Notes 1995, Swiss Society for Astrophysics and Astronomy |page=108 |date=1997 |isbn=978-3-540-61520-0 |chapter-url=https://books.google.com/books?id=79OhUC30PkkC&pg=PA108}}</ref>

In 1928, [[Edwin Hubble]] proposed associating the cloud with the star of 1054, an idea that remained controversial until the nature of supernovae was understood, and it was [[Nicholas Mayall]] who indicated that the star of 1054 was undoubtedly the supernova whose explosion produced the Crab Nebula. The search for historical supernovae started at that moment: seven other historical sightings have been found by comparing modern observations of supernova remnants with astronomical documents of past centuries.{{Citation needed|date=July 2023}}

After the original connection to Chinese observations, in 1934 connections were made to a 13th-century Japanese reference to a "[[Guest star (astronomy)|guest star]]" in [[Meigetsuki]] a few weeks before the Chinese reference.<ref name="Usui2007">{{cite web|title=Why and how did a Japanese poet record the Supernova of AD 1054?|url=http://homepage3.nifty.com/silver-moon/teika/teika-e.htm|last=Usui|first=Tadashi|date=11 January 2007|archive-url=https://web.archive.org/web/20160303193701/http://homepage3.nifty.com/silver-moon/teika/teika-e.htm|archive-date=3 March 2016|access-date=4 March 2015}}</ref><ref>{{cite book|author=Fujiwara no Sadaie|title=Meigetsuki|date=c. 1200|trans-title=Record of the Clear Moon|author-link=Fujiwara no Teika}}</ref><ref>{{Cite journal |last1=Stephenson |first1=F. Richard |last2=Green |first2=David A. |year=2003 |title=Was the supernova of AD 1054 reported in European history? |journal=Journal of Astronomical History and Heritage |volume=6 |issue=1 |page=46 |bibcode=2003JAHH....6...46S |doi=10.3724/SP.J.1440-2807.2003.01.05 |s2cid=128868531}}</ref> The event was long considered unrecorded in Islamic astronomy,<ref>{{cite journal|last=Gingerich|first=Owen|author-link=Owen Gingerich|date=April 1986|title=Islamic astronomy|url=http://www.as.utexas.edu/astronomy/education/spring05/bromm/readings/islam.pdf|journal=Scientific American|volume=254|issue=10|page=74|bibcode=1986SciAm.254d..74G|doi=10.1038/scientificamerican0486-74}}</ref> but in 1978 a reference was found in a 13th-century copy made by [[Ibn Abi Usaibia]] of a work by [[Ibn Butlan]], a [[Nestorian]] Christian physician active in Baghdad at the time of the supernova.<ref name="Usaybia">{{cite book|author=Ibn Abi Usaibia|title=Lives of the Physicians|date=1971|others=Kopf, Lothar (trans.)|chapter=Chapter 10: On the Classes of Physicians of Iraq, al-Jazirah and Diyar Bekr|author-link=Ibn Abi Usaibia|orig-date=1245–1246|chapter-url=http://www.tertullian.org/fathers/ibn_abi_usaibia_02.htm#CHAPTER_X}}</ref><ref name="Green03">{{cite book|last1=Green|first1=David A.|last2=Stephenson|first2=F. Richard|chapter=Historical Supernovae |title=Supernovae and Gamma-Ray Bursters |date=2003|publisher=Springer|isbn=978-3-540-44053-6|editor1-last=Weiler|editor1-first=K. W.|series=Lecture Notes in Physics|volume=598|location=Berlin|pages=7–19|arxiv=astro-ph/0301603|bibcode=2003LNP...598....7G|doi=10.1007/3-540-45863-8_2|s2cid=17099919|name-list-style=amp}}</ref>

Given its great distance, the daytime "guest star" observed by the Chinese could only have been a [[supernova]]—a massive, exploding star, having exhausted its supply of energy from [[nuclear fusion]] and collapsed in on itself.<ref>{{Cite book|last=Tao|first=Li|title=Xu Zizhi Tongjian Changbian|publisher=Zhonghua Book Company|year=2004|volume=176|location=Beijing|page=4263|language=zh|quote=己丑，客星出天关之东南可数寸。嘉祐元年三月乃没。}}</ref><ref>{{Cite book|title=Song Huiyao|language=zh|quote=嘉佑元年三月，司天监言：'客星没，客去之兆也'。初，至和元年五月，晨出东方，守天关。昼如太白，芒角四出，色赤白，凡见二十三日。}}</ref> Recent analysis of historical records have found that the supernova that created the Crab Nebula probably appeared in April or early May, rising to its maximum brightness of between [[apparent magnitude]] −7 and −4.5 (brighter even than Venus' −4.2 and everything in the night sky except the [[Moon]]) by July. The supernova was visible to the [[naked eye]] for about two years after its first observation.<ref name="Collinsetal1999">{{cite journal |last1=Collins |first1=George W. II |last2=Claspy |first2=William P. |last3=Martin |first3=John C. |display-authors=1 |title=A Reinterpretation of Historical References to the Supernova of A.D. 1054 |journal=[[Publications of the Astronomical Society of the Pacific]] |volume=111 |issue=761 |pages=871–880 |date=1999 |bibcode=1999PASP..111..871C |doi=10.1086/316401 |arxiv=astro-ph/9904285|s2cid=14452581 }}</ref>