View source for Solar eclipses on Jupiter

{{Short description|When moons of Jupiter pass before the Sun}}
{{More citations needed|date=August 2017}}
[[File:JupiterandIo.jpg|thumb|right|A picture of [[Jupiter]] and its moon [[Io (moon)|Io]] taken by the [[Hubble Space Telescope]]. The black spot is Io's shadow.]]
[[File:Jupiter and Red Spot, Ganymede (and transit), Io, Europa, and Callisto, taken with Nikon P900 - 2020-07-24.jpg|thumb|right|[[Jupiter]] and the [[Great Red Spot]] (visible on the lower right), with [[Ganymede (moon)|Ganymede]] (immediately on the upper right) casting its shadow on Jupiter. The other moons are [[Europa (moon)|Europa]] (further right), [[Io (moon)|Io]] (first on left), and [[Callisto (moon)|Callisto]] (furthest on left). Photo taken with [[Nikon Coolpix P900|Nikon P900]] on 24 July 2020, ten days after [[Opposition (astronomy)|opposition]].]]

'''Solar eclipses on Jupiter''' occur when any of the [[natural satellite]]s of [[Jupiter]] pass in front of the [[Sun]] as seen from the planet Jupiter.<ref>{{Cite web|title=NASA's Juno Mission Checks Out Epic Io Eclipse on Jupiter {{!}} Space|url=https://www.space.com/amp/juno-sees-io-moon-shadow-on-jupiter.html|access-date=2020-12-29|website=www.space.com|date=17 September 2019 }}</ref>

For bodies that appear smaller in [[angular diameter]] than the Sun, the proper term would be a [[astronomical transit|transit]]. For bodies that are larger than the apparent size of the Sun, the proper term would be an [[occultation]].

There are four satellites capable of completely occulting the Sun: [[Io (moon)|Io]], [[Europa (moon)|Europa]], [[Ganymede (moon)|Ganymede]] and [[Callisto (moon)|Callisto]]. All of the others are too small or too distant to be able to completely occult the Sun, so can only transit the Sun.  Most of the more distant satellites also have orbits that are strongly inclined to the plane of Jupiter's orbit, and would rarely be seen transiting Jupiter.

When the four largest satellites of Jupiter, the [[Galilean moon|Galilean satellites]], occult the Sun, a ''shadow transit'' can be seen on the surface of Jupiter which can be observed from Earth in [[telescope]]s.

[[File:Jupiter_éclipse_Io.jpg|thumb|Io shadow on Jupiter.]]

Eclipses of the Sun from Jupiter are not particularly rare, since Jupiter is very large and its [[axial tilt]] (which is related to the plane of the [[orbit]]s of its satellites) is relatively small—indeed, the vast majority of the orbits of all four of the objects capable of occulting the Sun will result in a solar occultation visible from somewhere on Jupiter, with every satellite except Callisto guaranteed to produce an eclipse on every orbit.

The related phenomenon of satellite eclipses in the shadow of Jupiter has been observed since the time of [[Giovanni Cassini]] and [[Ole Rømer]] in the mid Seventeenth Century.  It was soon noticed that predicted times differed from observed times in a regular way, varying from up to ten minutes early to up to ten minutes late.  Rømer correctly realized that the variations were caused by the varying distance between Earth and Jupiter as the two planets moved in their [[orbit]]s around the [[Sun]]. Later, in 1678, [[Christiaan Huygens]] used these errors to make the first accurate determination of the [[speed of light]].

Spacecraft can be used to observe the solar eclipses on Jupiter; these include ''[[Pioneer 10]]'' and ''[[Pioneer 11]]'' (1973 and 1974), ''[[Voyager 1]]'' and ''[[Voyager 2]]'' (1979), ''[[Galileo (spacecraft)|Galileo]]'' orbiter (1995–2003), ''[[Cassini–Huygens]]'' (2000), ''[[New Horizons]]'' (2007), and ''[[Juno (spacecraft)|Juno]] '' (2016-present) observed the transits of their moons and its shadows.

==Visibility from Jupiter==
The [[mean]] [[angular diameter]] of the [[Sun]] as viewed from Jupiter is 372 [[minute and second of arc|arc-seconds]], or 6' 12" (about {{fract|1|5}} that of the Sun as viewed from Earth), varying slightly from 381" at [[perihelion]] to 357" at [[aphelion]]. Unlike the near coincidence of the apparent sizes of the Moon and Sun as viewed from Earth, this perspective exaggerates the apparent diameters of all the [[Galilean moons]] in comparison to the Sun. Even distant [[Callisto (moon)|Callisto]] is over 50% larger, and [[Io (moon)|Io]] is nearly six times as large. This disparity in angular size makes the moons' shadows on Jupiter [[hard and soft light|more defined]] than the lunar shadow on Earth during a total [[solar eclipse]], as it narrows the [[penumbra]] for a given distance.<ref>{{cite web |url=http://www.sydneyobservatory.com.au/2010/shadows-on-jupiter-cast-by-the-galilean-moons-how-often-and-how-many-can-there-be/ |title=Shadows on Jupiter Cast by the Galilean Moons |publisher=[[Sydney Observatory]] |year=2010 |access-date=2014-05-07 |archive-url=https://web.archive.org/web/20140508062052/http://www.sydneyobservatory.com.au/2010/shadows-on-jupiter-cast-by-the-galilean-moons-how-often-and-how-many-can-there-be/ |archive-date=2014-05-08 |url-status=dead }}</ref>

== Gallery ==
<gallery widths="200">
File:Jupiter double shadow transit.jpg|A computer-generated image showing a double shadow transit on Jupiter. The two satellites visible, Io and Europa, just to the right of the planet, are responsible for the shadows.
File:Jupiter-io-transit feb 10 2009.gif|A simulated view of an Io transit of Jupiter as viewed from the Earth, showing the shadow apparently leading Io.
</gallery>

==References==
{{Reflist}}

==External links==
*{{APOD |date=13 October 1995|title=Jupiter, Io and Ganymede's Shadow}}
*{{APOD |date=7 October 1996|title=Io's Shadow}}
*{{APOD |date=2 February 1998|title=A Triple Eclipse on Jupiter}}
*{{APOD |date=7 December 2002|title=Jupiter, Io and Shadow}}
*{{APOD |date=27 February 2003|title=When Moons and Shadows Dance}}
*{{APOD|date=11 November 2004|title=Pastel Planet, Triple Eclipse}}
*{{APOD|date=15 February 2013|title=Shadows Across Jupiter}}
*{{APOD|date=6 February 2015|title=Jupiter Triple-Moon Conjunction}} - includes shadows only from Europa and distant Callisto
*Brufau, Rainer. (2021). Triple shadow phenomena on Jupiter, Saturn and Uranus from 1000 CE to 3000 CE (Version 0) [Data set]. Zenodo. https://doi.org/10.5281/zenodo.5515898

{{Solar eclipses|state=collapsed}}
{{Jupiter}}

[[Category:Solar eclipses by planet]]
[[Category:Jupiter]]