Editing Spheroid (section)

===Prolate spheroids===
[[File:Gilbert_rugby_ball_on_grass.jpg|thumb|left|A [[rugby ball]].]]
The prolate spheroid is the approximate shape of the ball in several sports, such as in the [[rugby ball]].

Several [[moons]] of the Solar System approximate prolate spheroids in shape, though they are actually [[triaxial ellipsoid]]s. Examples are [[Saturn]]'s satellites [[Mimas (moon)|Mimas]], [[Enceladus (moon)|Enceladus]], and [[Tethys (moon)|Tethys]] and [[Uranus]]'s satellite [[Miranda (moon)|Miranda]].

In contrast to being distorted into oblate spheroids via rapid rotation, celestial objects distort slightly into prolate spheroids via [[tide|tidal forces]] when they orbit a massive body in a close orbit. The most extreme example is Jupiter's moon [[Io (moon)|Io]], which becomes slightly more or less prolate in its orbit due to a slight eccentricity, causing intense [[volcanism]]. The major axis of the prolate spheroid does not run through the satellite's poles in this case, but through the two points on its equator directly facing toward and away from the primary. This combines with the smaller oblate distortion from the synchronous rotation to cause the body to become triaxial.

The term is also used to describe the shape of some [[nebula]]e such as the [[Crab Nebula]].<ref name="Trimble1973">{{ citation | last1 = Trimble | first1 = Virginia Louise | author1-link = Virginia Trimble | title = The Distance to the Crab Nebula and NP 0532 | date = October 1973 | journal = Publications of the Astronomical Society of the Pacific | volume = 85 | issue = 507 | page = 579 | bibcode = 1973PASP...85..579T | doi = 10.1086/129507 | doi-access = free }}</ref> [[Fresnel zone]]s, used to analyze wave propagation and interference in space, are a series of concentric prolate spheroids with principal axes aligned along the direct line-of-sight between a transmitter and a receiver.

The [[atomic nucleus|atomic nuclei]] of the [[actinide]] and [[lanthanide]] elements are shaped like prolate spheroids.<ref>{{Cite web|url=https://www.britannica.com/science/nuclear-fission/Fission-theory|title=Nuclear fission - Fission theory|website=Encyclopedia Britannica}}</ref> In anatomy, near-spheroid organs such as [[testicle|testis]] may be measured by their [[Anatomical terms of location#Axes|long and short axes]].<ref>[https://books.google.com/books?id=safNmcP3lakC&pg=PA559 Page 559] in: {{cite book|title=Introduction to Vascular Ultrasonography|author=John Pellerito, Joseph F Polak|edition=6|publisher=Elsevier Health Sciences|year=2012|isbn=9781455737666}}</ref>

Many submarines have a shape which can be described as prolate spheroid.<ref name="scientific american">{{cite web |url=http://www.scientificamerican.com/article/football-science-shapes/ |title=What Do a Submarine, a Rocket and a Football Have in Common? |work=[[Scientific American]] |date=8 November 2010 |access-date=13 June 2015 }}</ref>