Editing Leo (constellation) (section)

===Deep-sky objects===
Leo contains many bright [[galaxy|galaxies]];  [[Messier 65]], [[Messier 66]], [[Messier 95]], [[Messier 96]], [[Messier 105]], and [[NGC 3628]] are the most famous{{citation needed|date=November 2022}}, the first two being part of the [[Leo Triplet]].

The [[Leo Ring]], a cloud of hydrogen, helium gas, is found in the orbit of two galaxies found within this constellation.[[File:Phot-33c-03-fullres.jpg|thumbnail|left|Messier 66]] M66 is a spiral galaxy that is part of the Leo Triplet, whose other two members are M65 and NGC 3628. It is at a distance of 37 million light-years and has a somewhat distorted shape due to gravitational interactions with the other members of the Triplet, which are pulling stars away from M66. Eventually, the outermost stars may form a dwarf galaxy orbiting M66.<ref name="objects">{{cite book |title = 300 Astronomical Objects: A Visual Reference to the Universe |last1 = Wilkins |first1 = Jamie |last2 = Dunn |first2 = Robert |publisher = Firefly Books |location = Buffalo, New York |date = 2006 |isbn = 978-1-55407-175-3}}</ref> Both M65 and M66 are visible in large binoculars or small telescopes, but their concentrated nuclei and elongation are only visible in large amateur instruments.{{sfn|Ridpath|Tirion|2001|pp=166-168}}

[[File: A Horseshoe Einstein Ring from Hubble.JPG|thumb|The notable [[gravitational lens]] known as the [[Cosmic Horseshoe]]]]
M95 and M96 are both [[spiral galaxies]] 20 million light-years from Earth. Though they are visible as fuzzy objects in small telescopes, their structure is only visible in larger instruments. M95 is a [[barred spiral galaxy]]. M105 is about a degree away from the M95/M96 pair; it is an [[elliptical galaxy]] of the 9th magnitude, also about 20 million light-years from Earth.{{sfn|Ridpath|Tirion|2001|pp=166-168}}

[[NGC 2903]] is a [[barred spiral galaxy]] discovered by [[William Herschel]] in 1784. It is very similar in size and shape to the Milky Way and is located 25 million light-years from Earth. In its core, NGC 2903 has many "hotspots", which have been found to be near regions of [[star formation]]. The star formation in this region is thought to be due to the presence of the dusty bar, which sends shock waves through its rotation to an area with a diameter of 2,000 light-years. The outskirts of the galaxy have many young [[open cluster]]s.<ref name=" objects"/>

Leo is also home to some of the largest structures in the observable universe. Some of the structures found in the constellation are the [[Clowes–Campusano LQG]], [[U1.11]], [[U1.54]], and the [[Huge-LQG]], which are all [[large quasar group]]s; the latter being the second largest structure known<ref>{{cite news|date= 11 January 2013|last=Prostak|first=Sergio|title=Universe's Largest Structure Discovered|url=http://www.sci-news.com/astronomy/article00818.html|publisher=scinews.com|access-date=15 January 2013}}</ref> (see also [[NQ2-NQ4 GRB overdensity]]).