Editing Carina (constellation) (section)

=== Deep-sky objects ===
Carina is known for its [[Carina Nebula|namesake nebula]], NGC 3372,{{sfn|Levy|2005|p=100}} discovered by French astronomer [[Nicolas-Louis de Lacaille]] in 1751, which contains several [[nebula]]e. The Carina Nebula overall is an extended [[emission nebula]] approximately 8,000 light-years away and 300 light-years wide that includes vast [[star formation|star-forming regions]].{{sfn|Wilkins|Dunn|2006|p={{page needed|date=July 2012}}}} It has an overall magnitude of 8.0{{sfn|Levy|2005|p=101}} and an apparent diameter of over 2 degrees.{{sfn|Ridpath|Tirion|2001|pp=104–106}} Its central region is called the Keyhole, or the [[Keyhole Nebula]]. This was described in 1847 by [[John Herschel]], and likened to a keyhole by Emma Converse in 1873.<ref name=appletons>{{cite book|title=Appletons' Journal|url=https://books.google.com/books?id=BgMZAAAAYAAJ&pg=PA818|year=1873|publisher=[[D. Appleton and Company]]|pages=818–}}</ref> The Keyhole is about seven light-years wide and is composed mostly of [[ionized hydrogen]], with two major star-forming regions. The [[Homunculus Nebula]] is a [[planetary nebula]] visible to the naked eye that is being ejected by the erratic [[luminous blue variable]] star [[Eta Carinae]], the most massive visible star known. Eta Carinae is so massive that it has reached the theoretical upper limit for the mass of a star and is therefore unstable. It is known for its outbursts; in 1840 it briefly became one of the brightest stars in the sky due to a particularly massive outburst, which largely created the Homunculus Nebula. Because of this instability and history of outbursts, Eta Carinae is considered a prime [[supernova]] candidate for the next several hundred thousand years because it has reached the end of its estimated million-year life span.{{sfn|Wilkins|Dunn|2006|p={{page needed|date=July 2012}}}}

[[NGC 2516]] is an open cluster that is both quite large<ref name=":0">{{Cite book |last=Chartrand |first=Mark R |title=National Audubon Society Field Guide to the Night Sky |publisher=Alfred A. Knopf, Inc. |year=1991 |isbn=0-679-40852-5 |location=New York, USA |pages=470}}</ref> (approximately half a degree square) and bright, visible to the unaided eye.<ref name=":0" /> It is located 1,100 light-years from Earth and has approximately 80 stars, the brightest of which is a [[red giant]] star of magnitude 5.2. [[NGC 3114]] is another open cluster approximately of the same size, though it is more distant at 3,000 light-years from Earth. It is more loose and dim than NGC 2516, as its brightest stars are only 6th magnitude. The most prominent open cluster in Carina is [[IC 2602]], also called the "Southern [[Pleiades]]". It contains [[Theta Carinae]], along with several other stars visible to the unaided eye. In total, the cluster possesses approximately 60 stars. The Southern Pleiades is particularly large for an open cluster, with a diameter of approximately one degree. Like IC 2602, [[NGC 3532]] is visible to the unaided eye<ref name=":0" /> and is of comparable size. It possesses approximately 150 stars that are arranged in an unusual shape, approximating an [[ellipse]] with a dark central area. Several prominent orange giants are among the cluster's bright stars, of the 7th magnitude. Superimposed on the cluster is [[Chi Carinae]], a yellow-white-hued star of magnitude 3.9, far more distant than NGC 3532.{{sfn|Ridpath|Tirion|2001|pp=104–106}}

Carina also contains the naked-eye [[globular cluster]] [[NGC 2808]].<ref name=":0" /> [[Epsilon Carinae]] and [[Upsilon Carinae]] are double stars visible in small telescopes.

One noted [[galaxy cluster]] is 1E 0657-56, the [[Bullet Cluster]]. At a distance of 4 billion light-years ([[redshift]] 0.296), this galaxy cluster is named for the [[bow shock|shock wave]] seen in the [[intracluster medium]], which resembles the shock wave of a supersonic bullet. The bow shock visible is thought to be due to the smaller galaxy cluster moving through the intracluster medium at a relative speed of 3,000–4,000 kilometers per second to the larger cluster. Because this [[gravitational interaction]] has been ongoing for hundreds of millions of years, the smaller cluster is being destroyed and will eventually merge with the larger cluster.{{sfn|Wilkins|Dunn|2006|p={{page needed|date=July 2012}}}}