View source for Extraterrestrial sky

{{Short description|Extraterrestrial view of outer space}}
{{For|the view from above the astronomical object's surface|Extraterrestrial atmospheres}}
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{{more references needed|date=April 2024}}
{{original research|date=April 2024}}
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{{Use American English|date=December 2024}}
{{use mdy dates |date=February 2016}}
[[File:NASA-Apollo8-Dec24-Earthrise.jpg|thumb|350px|right|A historic extraterrestrial sky—''[[Earthrise]]'', the [[Earth]] viewed from the [[Moon]]. Taken by [[Apollo 8]] astronaut [[William Anders]] while in [[lunar orbit]], December 24, 1968.]]
In [[astronomy]], an '''extraterrestrial sky''' is a view of [[outer space]] from the surface of an astronomical body other than [[Earth]].

The only extraterrestrial [[sky]] that has been directly observed and photographed by [[astronaut]]s is that of the [[Moon]]. The skies of [[Venus]], [[Mars]] and [[Titan (moon)|Titan]] have been observed by [[space probe]]s designed to land on the surface and transmit images back to Earth.

Characteristics of extraterrestrial sky appear to vary substantially due to a number of factors. An [[extraterrestrial atmosphere]], if present, has a large bearing on visible characteristics. The [[atmosphere]]'s density and [[chemical composition]] can contribute to differences in [[color]], [[Opacity (optics)|opacity]] (including [[haze]]) and the presence of [[cloud]]s.<ref name="LS-20200704">{{cite news |last=Coffey |first=Donavyn |title=What color is the sunset on other planets? |url=https://www.livescience.com/what-color-are-other-planets-sunsets.html |date=July 4, 2020 |work=[[Live Science]] |access-date=July 4, 2020 }}</ref> Astronomical objects may also be visible and can include [[natural satellite]]s, [[planetary ring|ring]]s, [[star system]]s and [[nebula]]s and other [[planetary system]] bodies.

==Luminosity and angular diameter of the Sun==
{{main article|Solar luminosity}}
{{Further|Angular diameter}}

The [[Sun]]'s [[apparent magnitude]] changes according to the [[inverse square law]], therefore, the difference in magnitude as a result of greater or lesser distances from different [[celestial bodies]] can be predicted by the following [[formula]]:

:<math> \text{intensity} \ \propto \ \frac{1}{\text{distance}^2} \, </math>

Where "distance" can be in [[km]], [[Astronomical unit|AU]], or any other appropriate unit.

To illustrate, since [[Pluto]] is 40 AU away from the Sun on average, it follows that the parent star would appear to be <math>\frac{1}{1600}</math> times as bright as it is on [[Earth]].

Though a [[Terrestrial planet|terrestrial]] observer would find a dramatic decrease in available [[sunlight]] in these environments, the Sun would still be bright enough to cast shadows even as far as the hypothetical [[Planet Nine]], possibly located 1,200 AU away, and by analogy would still outshine the [[full Moon]] as seen from Earth.

The change in angular diameter of the Sun with distance is illustrated in the diagram below:

[[File:Angular dia formula.JPG|thumb|200px|right|Diagram for the formula of the angular diameter]]
The angular diameter of a [[circle]] whose plane is perpendicular to the displacement vector between the point of view and the centre of said circle can be calculated using the formula<ref group="nb">This can be derived using the formula for the length of a cord found at http://mathworld.wolfram.com/CircularSegment.html</ref>
:<math>\delta =  2\arctan \left(\frac{d}{2D}\right),</math>
in which <math>\delta</math> is the angular diameter, and <math>d</math> and <math>D</math> are the actual diameter of and the distance to the object. When <math>D \gg d</math>, we have <math>\delta \approx d / D</math>, and the result obtained is in [[radians]].

For a spherical object whose ''actual'' diameter equals <math>d_\mathrm{act},</math> and where <math>D</math> is the distance to the ''centre'' of the sphere, the angular diameter can be found by the formula
:<math>\delta =  2\arcsin \left(\frac{d_\mathrm{act}}{2D}\right)</math>

The difference is due to the fact that the apparent edges of a sphere are its tangent points, which are closer to the observer than the centre of the sphere. For practical use, the distinction is significant only for spherical objects that are relatively close, since the [[small-angle approximation]] holds for <math> x \ll 1</math>:<ref>{{Cite web |url=http://www.mathstat.concordia.ca/faculty/rhall/mc/arctan.pdf |title=Archived copy |access-date=August 5, 2017 |archive-url=https://web.archive.org/web/20150218190328/http://www.mathstat.concordia.ca/faculty/rhall/mc/arctan.pdf |archive-date=February 18, 2015 |url-status=dead }}</ref>
:<math>\arcsin x \approx \arctan x \approx x</math> .

==Horizon==
On [[terrestrial planet]]s and other solid celestial bodies with negligible atmospheric effects, the distance to the [[horizon]] for a "standard observer" varies as the square root of the planet's radius. Thus, the horizon on [[Mercury (planet)|Mercury]] is 62% as far away from the observer as it is on Earth, on [[Mars]] the figure is 73%, on the [[Moon]] the figure is 52%, on [[Mimas (moon)|Mimas]] the figure is 18%, and so on. The observer's height must be taken into account when calculating the distance to the horizon.

==Mercury==
{{See Also| Astronomy on Mercury}}
[[File:EW1027346412Gnomap.png|thumb|200px|right|Mercury – sky viewed from orbit]]
Because [[Mercury (planet)|Mercury]] has little [[Atmosphere of Mercury|atmosphere]], a view of the planet's skies would be no different from viewing space from orbit. Mercury has a southern [[pole star]], [[Alpha Pictoris|α Pictoris]], a magnitude 3.2 star. It is fainter than Earth's [[Polaris]] (α Ursae Minoris).<ref>{{cite web |url=http://www.windows.ucar.edu/tour/link=/mercury/Atmosphere/atmosphere.html |title=Thin Atmosphere of Mercury, Formation and Composition – Windows to the Universe |website=www.windows.ucar.edu |access-date=September 5, 2008 |archive-url=https://web.archive.org/web/20100327214903/http://www.windows.ucar.edu/tour/link=/mercury/Atmosphere/atmosphere.html |archive-date=March 27, 2010 |url-status=dead }}</ref> [[Omicron Draconis]] is its north star.<ref>2004. Starry Night Pro, Version 5.8.4. [[Imaginova]]. {{ISBN|978-0-07-333666-4}}. www.starrynight.com</ref>

===Other planets seen from Mercury===
After the Sun, the second-brightest object in the Mercurian sky is [[Venus]], which is much brighter there than for terrestrial observers. The reason for this is that when Venus is closest to Earth, it is between the Earth and the Sun, so we see only its night side. Indeed, even when Venus is brightest in the Earth's sky, we are actually seeing only a narrow crescent. For a Mercurian observer, on the other hand, Venus is closest when it is in [[Astronomical opposition|opposition]] to the Sun and is showing its full disk. The [[apparent magnitude]] of Venus is as bright as −7.7.<ref name="Perelman">{{cite book
 |first1 = Yakov |last1=Perelman |first2=Arthur |last2=Shkarovsky-Raffe
 |year = 2000
 |title = Astronomy for Entertainment
 |url = https://books.google.com/books?id=2Sc_eaR9c9UC&q=%22Earth+from+Mercury%22+magnitude&pg=PA147|publisher = University Press of the Pacific
 |isbn = 978-0-89875-056-0 }}</ref>

The Earth and the Moon are also very prominent, their apparent magnitudes being about −5<ref name="Perelman" /> and −1.2, respectively. The maximum apparent distance between the Earth and the Moon is about 15′. All other planets are visible just as they are on Earth, but somewhat less bright at opposition with the difference being most considerable for [[Mars]].

The [[zodiacal light]] is probably more prominent than it is from Earth.

==Venus==
The atmosphere of [[Venus]] is so thick that the Sun is not distinguishable in the daytime sky, and the [[star]]s are not visible at night. Being closer to the Sun, Venus receives about 1.9 times more sunlight than Earth, but due to the thick atmosphere, only about 20% of the light reaches the surface.<ref>{{cite news |url=https://www.seti.org/press-release/possible-venus-twin-discovered-around-dim-star |title=Possible Venus twin discovered around dim star |date=April 6, 2017 |publisher=SETI Institute}}</ref><ref>{{Cite book|url=https://books.google.com/books?id=IMkSBAAAQBAJ&dq=%22block+out+80+per+cent+of+all+sunlight%22&pg=PA62|title=The Planets: The Definitive Visual Guide to Our Solar System|date=1 September 2014|publisher=Dorling Kindersley Limited|isbn=978-0-241-18676-3 |accessdate=6 October 2023|via=Google Books}}</ref> Color images taken by the Soviet [[Venera program|Venera]] probes suggest that the sky on Venus is [[Orange (color)|orange]].<ref>{{cite web |url=http://solarsystem.nasa.gov/missions/venera_13/ |title=Venera 13 – Missions – NASA Solar System Exploration |website=NASA Solar System Exploration |access-date=December 22, 2015 |archive-date=March 6, 2016 |archive-url=https://web.archive.org/web/20160306023924/http://solarsystem.nasa.gov/missions/venera_13/ |url-status=dead }}</ref> If the Sun could be seen from Venus's surface, the time from one sunrise to the next (a [[solar day]]) would be 116.75 Earth days. Because of Venus's [[retrograde motion|retrograde rotation]], the Sun would appear to rise in the west and set in the east.<ref>{{cite web |url=http://www.planetary.org/explore/topics/compare_the_planets/terrestrial.html |archive-url=https://web.archive.org/web/20110728044444/http://www.planetary.org/explore/topics/compare_the_planets/terrestrial.html |archive-date=28 July 2011 |title=The Terrestrial Planets |publisher=The Planetary Society |access-date=3 August 2007 |url-status=dead }}</ref>

An observer aloft in Venus's cloud tops, on the other hand, would circumnavigate the planet in about four Earth days and see a sky in which Earth and the Moon shine brightly (about magnitudes −6.6<ref name="Perelman" /> and −2.7, respectively) at [[opposition (planets)|opposition]]. The maximum angular separation between the Moon and Earth from the perspective of Venus is 0.612°, or approximately the same separation of one centimetre of separation at a distance of one metre and coincidentally, about the apparent size of the Moon as seen from Earth. Mercury would also be easy to spot, because it is closer and brighter, at up to magnitude −2.7,<ref name="Perelman" /> and because its maximum [[Elongation (astronomy)|elongation]] from the Sun is considerably larger (40.5°) than when observed from Earth (28.3°).

[[42 Draconis]] is the closest star to the north pole of [[Venus]]. [[Eta¹ Doradus]] is the closest to its south pole. (Note: The IAU uses the [[right-hand rule]] to define a ''positive pole'' for the purpose of determining orientation. Using this convention, Venus is tilted 177° ("upside down"), and the positive pole is instead the south pole.)<ref>{{Cite journal
| doi = 10.1007/s10569-010-9320-4
| title = Report of the IAU Working Group on Cartographic Coordinates and Rotational Elements: 2009
| url = http://astropedia.astrogeology.usgs.gov/alfresco/d/d/workspace/SpacesStore/28fd9e81-1964-44d6-a58b-fbbf61e64e15/WGCCRE2009reprint.pdf <!--
| url = http://astropedia.astrogeology.usgs.gov/download/Docs/WGCCRE/WGCCRE2009reprint.pdf -->
| journal = Celestial Mechanics and Dynamical Astronomy
| volume = 109 | issue = 2 | pages = 101–135
| year = 2010
| last1 = Archinal | first1 = Brent A.
| last2 = A'Hearn | first2 = Michael F.
| last3 = Bowell | first3 = Edward G.
| last4 = Conrad | first4 = Albert R.
| last5 = Consolmagno | first5 = Guy J.
| display-authors = 5
| last6 = Courtin | first6 = Régis
| last7 = Fukushima | first7 = Toshio
| last8 = Hestroffer | first8 = Daniel
| last9 = Hilton | first9 = James L.
| last10 = Krasinsky | first10 = George A.
| last11 = Neumann | first11 = Gregory A.
| last12 = Oberst | first12 = Jürgen
| last13 = Seidelmann | first13 = P. Kenneth
| last14 = Stooke | first14 = Philip J.
| last15 = Tholen | first15 = David J.
| last16 = Thomas | first16 = Paul C.
| last17 = Williams | first17 = Iwan P.|bibcode = 2011CeMDA.109..101A | s2cid = 189842666
}}</ref>

==The Moon==
The [[Moon]]'s atmosphere is negligibly thin, essentially vacuum, so its sky is black, as in the case of Mercury. At lunar twilight astronauts have though observed some [[crepuscular rays]] and [[lunar horizon glow]] of the illuminated atmosphere, beside interplanetary light phenomenons like [[zodiacal light]].
Furthermore, the Sun is so bright that it is still impossible to see stars during the lunar daytime, unless the observer is well shielded from sunlight (direct or reflected from the ground).

The Moon has a southern polar star, [[Delta Doradus|δ Doradus]], a magnitude 4.34 star. It is better aligned than Earth's [[Polaris]] (α Ursae Minoris), but much fainter. Its north pole star is [[Omicron Draconis]].<ref group="nb">note: due to [[axial precession]], the lunar pole describes a small circle on the celestial sphere every 18.6 years. {{citation |title=The Guinness Book of Astronomy Facts & Feats |page=29 |author=Patrick Moore |author-link=Patrick Moore |year=1983 |quote=In 1968 the north pole star of the Moon was Omega Draconis; by 1977 it was 36 Draconis. The south pole star is Delta Doradus.}}</ref>

<gallery class="center" widths="230px" heights="230px">
AS15-98-13325.jpg|Zodiacal light viewed from the Moon, during [[Apollo 15]]
Apollo 17 twilight ray sketch.jpg|The thin lunar atmosphere is visible on the Moon's surface at [[sunrise]] and [[sunset]] with the [[lunar horizon glow]]<ref name="The Planetary Society 2016">{{cite web | title=Lunar horizon glow from Surveyor 7 | website=The Planetary Society | date=May 6, 2016 | url=https://www.planetary.org/space-images/lunar-horizon-glow-surveyor-7 | access-date=Aug 8, 2022}}</ref> and lunar twilight rays, like Earth's [[crepuscular rays]]. This [[Apollo 17]] sketch depicts the glow and rays<ref name="Science Mission Directorate 2013">{{cite web | title=NASA Mission To Study Mysterious Lunar Twilight Rays | website=Science Mission Directorate | date=Sep 3, 2013 | url=https://science.nasa.gov/science-news/science-at-nasa/2013/03sep_ladee | access-date=Aug 8, 2022}}</ref> among the general [[zodiacal light]].<ref name="Colwell Robertson Horányi Wang 2009 pp. 2–9">{{cite journal | last1=Colwell | first1=Joshua E. | last2=Robertson | first2=Scott R. | last3=Horányi | first3=Mihály | last4=Wang | first4=Xu | last5=Poppe | first5=Andrew | last6=Wheeler | first6=Patrick | title=Lunar Dust Levitation - Journal of Aerospace Engineering - Vol 22, No 1 | journal=Journal of Aerospace Engineering | volume=22 | issue=1 | date=2009-01-01 | doi=10.1061/(ASCE)0893-1321(2009)22:1(2) | pages=2–9 | url=https://ascelibrary.org/doi/10.1061/%28ASCE%290893-1321%282009%2922%3A1%282%29 | access-date=2022-08-08}}</ref><ref name="EarthSky Updates on your cosmos and world 2014">{{cite web | title=The zodiacal light, seen from the moon | website=EarthSky | author=Deborah Byrd | date=Apr 24, 2014 | url=https://earthsky.org/space/the-zodiacal-light-seen-from-the-moon/ | access-date=Aug 8, 2022}}</ref>
</gallery>

===Sun and Earth in the lunar sky===
{{See also|Earth phase|Peak of eternal light}}
[[File:Moon Earth Comparison.png|thumb|In the Moon's sky Earth has an [[angular size]] of 1° 48{{prime}} to 2°,<ref name="Gorkavyi Krotkov Marshak 2023 pp. 1527–1537">{{cite journal | last1=Gorkavyi | first1=Nick | last2=Krotkov | first2=Nickolay | last3=Marshak | first3=Alexander | title=Earth observations from the Moon's surface: dependence on lunar libration | journal=Atmospheric Measurement Techniques | publisher=Copernicus GmbH | volume=16 | issue=6 | date=2023-03-24 | issn=1867-8548 | doi=10.5194/amt-16-1527-2023 | pages=1527–1537| s2cid=257753776 | doi-access=free | bibcode=2023AMT....16.1527G }}</ref> about 3.7 times the apparent size of the Moon or Sun in Earth's sky (due to the near equal apparent size of the Moon and Sun at [[lunar distance]]).]]

While the Sun moves across the Moon's sky within fourteen days, the daytime of a [[lunar day]] or the [[lunar month]], Earth is only visible on the [[Near side of the Moon|Moon's near side]] and moves around a central point in the near side's sky.

This is due to the Moon always facing the Earth with the same side, a result of the Moon's rotation being [[tidally locked]] to Earth. That said, the Earth does move around slightly around a central point in the Moon's sky, because of monthly [[libration]].
Therefore rising or setting of Earth at the horizon on the Moon occurs only at few lunar locations and only to a small degree, at the border of the [[near side of the Moon]] to the far side, and takes much longer than a sunrise or sunset on Earth due to the Moon's slow monthly rotation.

The famous [[Earthrise]] image by [[Apollo 8]] though is an instance where the astronauts moved around the Moon, making the Earth to rise above the Moon because of that motion.

===Eclipses from the Moon===
When sometimes the Moon, Earth and the Sun align exactly in a straight line (a [[syzygy (astronomy)|syzygy]]), the Moon or Earth move through the other's shadow, producing an [[eclipse]] for an observer on the surface in the shadow.

When the Moon moves into Earth's shadow a [[Solar eclipses on the Moon|Solar eclipse occurs on the near side of the Moon]] (which is observable as a [[Lunar eclipse]] facing the Moon).
Since the apparent diameter of the Earth is four times larger than that of the Sun, the Sun would be hidden behind the Earth for hours. [[Earth's atmosphere]] would be visible as a reddish ring. During the [[Apollo 15]] mission, an attempt was made to use the [[Lunar Roving Vehicle]]'s TV camera to view such an eclipse, but the camera or its power source failed after the astronauts left for Earth.<ref>{{cite web |url=http://www.hq.nasa.gov/alsj/a15/a15.launch.html |title=Return to Orbit |website=www.hq.nasa.gov }}</ref>

When Earth moves into the Moon's shadow a [[Solar eclipse]] occurs on Earth where the Moon's shadow passes, and is visible facing Earth as a tapered out lunar shadow on Earth's surface traveling across the full Earth's disk. The effect would be comparable to the shadow of a golf ball cast by sunlight on an object {{convert|5|m|feet|abbr=on|0}} away. Lunar observers with telescopes might be able to discern the [[umbra]]l shadow as a black spot at the center of a less dark region ([[penumbra]]). It would look essentially the same as it does to the [[Deep Space Climate Observatory]], which orbits Earth at the L1 [[Lagrangian point]] in the Sun-Earth system, {{convert|1.5|e6km|e6mi|abbr=unit}} from Earth.

<gallery class="center" widths="230px" heights="230px">
Eclipse from moon.jpg|A painting by [[Lucien Rudaux]] showing how a lunar eclipse might appear when viewed from the lunar surface.<ref name="Rudaux's painting">The Moon's surface appears red because the only sunlight available is refracted through Earth's atmosphere on the edges of Earth, as shown in the sky in this painting.</ref>
Lunar eclipse from moon-07aug28.png|A simulation of the start and end of the [[August 2007 lunar eclipse|August 28, 2007]] [[lunar eclipse]], viewed from the center of the Moon.<ref>Earth would be at&nbsp;''new'' phase  completely dark, except for sunlight [[atmospheric refraction|refracted]] through [[atmosphere of Earth|Earth's atmosphere]], visible as a reddish ring of light.</ref>
An_EPIC_Eclipse.gif|From space, the Moon's shadow during the [[solar eclipse of March 9, 2016]] appears as a dark spot moving across the Earth.
</gallery>

==Mars==
{{see also|Astronomy on Mars}}
[[Mars]] has only a thin atmosphere; however, it is extremely dusty and there is much light that is scattered about. The sky is thus rather bright during the daytime and stars are not visible. The Martian northern pole star is [[Deneb]],<ref>{{cite book |first=Eric |last=Burgess |title=To the Red Planet |url=https://archive.org/details/toredplanet0000burg |url-access=registration |publisher=Columbia University Press |year=1978 |isbn=9780231043922 }}; see [http://adsabs.harvard.edu/full/1993Ap&SS.201..160B review]: {{cite journal |first=Gurbir |last=Singh |journal=Astrophysics and Space Science |volume=201 |number=1 (February) |year=1993 |page=160 |title=Eric Burgess, to the red planet, Columbia University Press, 1978, 181 pp., many pictures, diagrams, and illustrations, an epilogue and an index, $19.95 |doi=10.1007/BF00626999 |s2cid=121342862 }}</ref> although the actual pole is somewhat offset in the direction of [[Alpha Cephei]]; it is more accurate to state that the top two stars of the [[Cygnus (constellation)|Northern Cross]], [[Gamma Cygni|Sadr]] and [[Deneb]], point to the north Celestial pole of Mars.<ref name="eknent">[http://www.eknent.com/etc/mars_np.png Mars] {{Webarchive|url=https://web.archive.org/web/20111028151559/http://www.eknent.com/etc/mars_np.png |date=October 28, 2011 }}</ref> [[Kappa Velorum]] is only a couple of degrees from the south Celestial pole of [[Mars]].<ref name="eknent" />

===The moons of Mars===
[[Phobos (moon)|Phobos]] appears in the sky of Mars with an [[angular size]] of 4.1{{prime}}, making its shape recognizable, appearing larger than Venus in Earth's sky, while the Moon appears in Earth's sky as large as 31{{prime}} on average.

===The color of the Martian sky===
Generating accurate true-color images from Mars' surface is surprisingly complicated.<ref>{{cite web |first=Phil |last=Plait |url=http://www.badastronomy.com/bad/misc/hoagland/mars_colors.html |title=Phil Plait's Bad Astronomy: Misconceptions: What Color is Mars? |website=Bad Astronomy}}</ref> To give but one aspect to consider, there is the [[Purkinje effect]]: the human eye's response to color depends on the level of ambient light; red objects appear to darken faster than blue objects as the level of illumination goes down. There is much variation in the color of the sky as reproduced in published images, since many of those images have used filters to maximize their scientific value and are not trying to show true color. For many years, the sky on Mars was thought to be more pinkish than it is now believed to be.

It is now known that during the Martian day, the sky is a [[butterscotch]] color.<ref>{{cite web |url=http://humbabe.arc.nasa.gov/mgcm/faq/sky.html |title=Why isn't the Martian sky blue like the Earth's |access-date=2005-04-23 |url-status=dead |archive-url=https://web.archive.org/web/20040810170442/http://humbabe.arc.nasa.gov/mgcm/faq/sky.html |archive-date=10 August 2004 |df=mdy-all }}</ref> Around sunset and sunrise, the sky is [[rose (color)|rose]] in color, but in the vicinity of the setting Sun it is blue. This is the opposite of the situation on Earth. Twilight lasts a long time after the Sun has set and before it rises because of the dust high in Mars's atmosphere.

On Mars, [[Rayleigh scattering]] is usually a very weak effect; the red color of the sky is caused by the presence of [[iron(III) oxide]] in the airborne dust particles. These particles are larger in size than gas molecules, so most of the light is scattered by [[Mie theory|Mie scattering]]. Dust absorbs blue light and scatters longer wavelengths (red, orange, yellow).
<gallery class="center">
File:PIA19401-MarsCuriosityRover-GaleCrater-Sunset-Animation-20150415.gif|Sunset, [[Gale crater]] – photo sequence by ''Curiosity'' rover, April 15, 2015
File:Mars sky at noon PIA01546.jpg|Mars sky at noon, as imaged by ''[[Mars Pathfinder]]'' (June 1999)
File:Mars sunset PIA01547.jpg|Mars sky at sunset, as imaged by ''[[Mars Pathfinder]]'' (June 1999)
File:MarsSunset losslesscrop.jpg|Mars sky at sunset, as imaged by the [[Spirit rover|''Spirit'' rover]] (May 2005)
File:Martian-Sunset-O-de-Goursac-Curiosity-2013.jpg|Mars sky at [[Sunset#Planets|sunset]], as imaged by the [[Curiosity rover|''Curiosity'' rover]] (February 2013; Sun simulated by artist)
</gallery>
===The Sun from Mars===
{{see also|Timekeeping on Mars}}
The [[Sun]] as seen from [[Mars]] appears to be {{frac|5|8}} the angular diameter as seen from Earth (0.35°), and sends 40% of the light, approximately the brightness of a slightly cloudy afternoon on [[Earth]].

On June 3, 2014, the [[Curiosity (rover)|''Curiosity'' rover]] on Mars observed the planet [[Mercury (planet)|Mercury]] transiting the Sun, marking the first time a [[planetary transit]] has been observed from a celestial body besides Earth.<ref name="NASA-20140610">{{cite web |last=Webster |first=Guy |title=Mercury Passes in Front of the Sun, as Seen From Mars |url=http://www.jpl.nasa.gov/news/news.php?release=2014-183 |date=10 June 2014 |work=[[NASA]] |access-date=10 June 2014 }}</ref>
{{clear}}

===Earth and Moon from Mars===
The Earth is visible from Mars as a double star; the Moon would be visible alongside it as a fainter companion. The difference in brightness between the two would be greatest around [[Conjunction (astronomy and astrology)|inferior conjunction]]. At that time, both bodies would present their dark sides to Mars, but Earth's atmosphere would largely offset this by refracting sunlight much like the atmosphere of Venus does. On the other hand, the airless Moon would behave like the similarly airless Mercury, going completely dark when within a few degrees of the Sun. At [[inferior conjunction]] (for the terrestrial observer, this is the [[Opposition (planets)|opposition]] of Mars and the Sun), the maximum visible distance between the Earth and the Moon would be about 25′, which is close to the [[apparent size]] of the Moon in Earth's sky. The angular size of Earth is between 48.1{{pprime}} and 6.6{{pprime}} and of the Moon between 13.3{{pprime}} and 1.7{{pprime}}, comparable to that of Venus and Mercury from Earth. Near maximum [[Elongation (astronomy)|elongation]] (47.4°), the Earth and Moon would shine at apparent magnitudes −2.5 and +0.9, respectively.<ref name="Perelman" /><ref name="EarthfromMars">{{cite web |date=2003-05-08 |title=Earth and Moon as Viewed from Mars |publisher=Earth Observatory |url=http://earthobservatory.nasa.gov/Newsroom/NewImages/images.php3?img_id=15293 |archive-url=https://web.archive.org/web/20030806111058/http://earthobservatory.nasa.gov/Newsroom/NewImages/images.php3?img_id=15293 |url-status=dead |archive-date=2003-08-06 |access-date=3 June 2008 }} (JPL Horizons shows: 0.9304AU from Earth; Phase 43%; Sun Elongation 43°)</ref>
{{clear}}
{| class="wikitable"
|-
! Year !! Event !! Image !! Refs
|-
|2003
|Earth and Moon, imaged by [[Mars Global Surveyor]] from its orbit around Mars on May 8, 2003, 13:00 [[UTC]]. South America is visible.
|[[File:Earth and Moon from Mars PIA04531.jpg|200px]]
|<ref name=Miles>{{Cite web|url=https://www.nationalgeographic.com/photography/photos/milestones-space-photography/|title=Milestones in Space Photography|website=[[National Geographic Society]]|date=November 11, 2010 |archiveurl=https://web.archive.org/web/20200401023314/https://www.nationalgeographic.com/photography/photos/milestones-space-photography/|archivedate=2020-04-01|url-status=dead}}</ref><ref name=Forbs>{{Cite web|url=https://www.forbes.com/sites/startswithabang/2016/08/22/viewing-the-earth-from-space-celebrates-70-years/#625ddad452ab|title=Viewing The Earth From Space Celebrates 70 Years|website=[[Forbes]]|date=August 22, 2016|archiveurl=https://web.archive.org/web/20160823175253/https://www.forbes.com/sites/startswithabang/2016/08/22/viewing-the-earth-from-space-celebrates-70-years/|archivedate=August 23, 2016|url-status=live}}</ref>
|-
|2014
|''[[Curiosity (rover)|Curiosity]]''{{'s}} first view of the Earth and the Moon from the surface of Mars (January 31, 2014).
|[[File:PIA17936-f2-MarsCuriosityRover-EarthMoon-20140131.jpg|200px]]
|<ref name="NYT-20140206">{{cite web |last=Revkin |first=Andrew C. |title=Martian View of Our Pale Dot |url=http://dotearth.blogs.nytimes.com/2014/02/06/a-martian-view-of-our-pale-dot |date=February 6, 2014 |work=The New York Times |accessdate=February 9, 2014 }}</ref>
|-
|2016
|Earth and the Moon as viewed from orbit around Mars<br />([[Mars Reconnaissance Orbiter|MRO]]; [[HiRISE]]; November 20, 2016)
|[[File:PIA21260 - Earth and Its Moon, as Seen From Mars.jpg|200px]]
|<ref name="NYT-20170109">{{cite news |last=St. Fleur |first=Nicholas |title=Looking at Your Home Planet from Mars |url=https://www.nytimes.com/2017/01/09/science/earth-from-mars-photo.html |date=January 9, 2017 |work=[[The New York Times]] |accessdate=January 9, 2017 }}</ref>
|}
{{multiple image|image3=MarsCuriosityRover-ViewsEarth&Venus-20200605.jpg |caption3=''Curiosity'' views Earth & Venus (5 June 2020) |width3=134 |footer= }}

===Venus from Mars===
[[Venus]] as seen from Mars (when near the maximum elongation from the Sun of 31.7°) would have an apparent magnitude of about −3.2.<ref name="Perelman" />

==Jupiter==
Although no images from within [[Jupiter]]'s atmosphere have ever been taken, artistic representations typically assume that the planet's sky is blue, though dimmer than Earth's, because the sunlight there is on average 27 times fainter, at least in the upper reaches of the atmosphere. The planet's narrow [[planetary ring|rings]] might be faintly visible from latitudes above the equator.{{citation needed|date=November 2019}} Further down into the atmosphere, the Sun would be obscured by clouds and haze of various colors, most commonly blue, brown, and red. Although theories abound on the cause of the colors, there is currently no unambiguous answer.<ref name="bagenal">{{cite web
 |year=2005
 |title=Class 17&nbsp;– Giant Planets
 |publisher=Laboratory for Atmospheric and Space Physics
 |first=Fran |last=Bagenal
 |url=http://lasp.colorado.edu/~bagenal/3720/CLASS17/17GiantPlanets1.html
 |access-date=5 September 2008}}</ref>

From Jupiter, the Sun appears to cover only 5 arcminutes, less than a quarter of its size as seen from Earth. The north pole of [[Jupiter]] is a little over two degrees away from [[Zeta Draconis]], while its south pole is about two degrees north of [[Delta Doradus]].

===Jupiter's moons as seen from Jupiter===
Aside from the Sun, the most prominent objects in Jupiter's sky are the four [[Galilean moon]]s. [[Io (moon)|Io]], the nearest to the planet, would be slightly larger than the full moon in Earth's sky, though less bright, and would be the largest moon in the Solar System as seen from its parent planet. The higher [[albedo]] of [[Europa (moon)|Europa]] would not overcome its greater distance from Jupiter, so it would not outshine Io. In fact, the low [[solar constant]] at Jupiter's distance (3.7% Earth's) ensures that none of the Galilean satellites would be as bright as the full moon is on Earth, and neither would any other moon in the Solar System.

[[File:Artist's Concept of Europa Water Vapor Plume.jpg|thumb|200px|right|[[Water vapor]] plume on [[Europa (moon)|Europa]] (artist concept; December 12, 2013)<ref name="NASA-20131212-EU">{{cite web |last1=Cook |first1=Jia-Rui C. |last2=Gutro |first2=Rob |last3=Brown |first3=Dwayne |last4=Harrington |first4=J. D. |last5=Fohn |first5=Joe |title=Hubble Sees Evidence of Water Vapor at Jupiter Moon |url=http://www.jpl.nasa.gov/news/news.php?release=2013-363|date=12 December 2013 |work=[[NASA]] |access-date=12 December 2013 }}</ref>]]

All four Galilean moons stand out because of the swiftness of their motion, compared to the Moon. They are all also large enough to fully [[eclipse]] the Sun.<ref name="CallistoSun">{{cite web
 |date = 3 June 2009
 |title = Pre-eclipse of the Sun by Callisto from the center of Jupiter
 |publisher = JPL Solar System Simulator
 |url = http://space.jpl.nasa.gov/cgi-bin/wspace?tbody=504&vbody=599&month=6&day=3&year=2009&hour=00&minute=20&fovmul=1&rfov=0.5&bfov=30&brite=1
 |archive-url = https://archive.today/20121213175433/http://space.jpl.nasa.gov/cgi-bin/wspace?tbody=504&vbody=599&month=6&day=3&year=2009&hour=00&minute=20&fovmul=1&rfov=0.5&bfov=30&brite=1
 |url-status = dead
 |archive-date = 13 December 2012
 |access-date = 4 June 2008 }}</ref> Because Jupiter's axial tilt is minimal, and the Galilean moons all orbit in the plane of Jupiter's equator, solar eclipses are quite common.

===The skies of Jupiter's moons===

None of Jupiter's moons have more than traces of atmosphere, so their skies are very nearly black. For an observer on one of the moons, the most prominent feature of the sky by far would be Jupiter. For an observer on [[Io (moon)|Io]], the closest large moon to the planet, Jupiter's apparent diameter would be about 20° (38 times the visible diameter of the Moon, covering 5% of Io's sky). An observer on [[Metis (moon)|Metis]], the innermost moon, would see Jupiter's apparent diameter increased to 68° (130 times the visible diameter of the Moon, covering 18% of Metis's sky). A "full Jupiter" over Metis shines with about 4% of the Sun's brightness (light on Earth from a full moon is 400,000 times dimmer than sunlight).

Because the inner moons of Jupiter are in [[synchronous rotation]] around Jupiter, the planet always appears in nearly the same spot in their skies (Jupiter would wiggle a bit because of the non-zero eccentricities). Observers on the sides of the Galilean satellites facing away from the planet would never see Jupiter, for instance.

From the moons of Jupiter, [[solar eclipse]]s caused by the Galilean satellites would be spectacular, because an observer would see the circular shadow of the eclipsing moon travel across Jupiter's face.<ref name="shadow">{{cite web
 |title=Jupiter Moon Shadow Transit
 |publisher=Jim Thommes Astrophotography
 |first=Jim |last=Thommes
 |url=http://www.jthommes.com/Astro/JupiterShadowSeq.htm
 |access-date=3 September 2008 }}</ref>

==Saturn==
[[File:Earth-Moon system as seen from Saturn (PIA17171).jpg|thumb|150px|left|NASA's [[Cassini spacecraft|''Cassini'' spacecraft]] photographs [[The Day the Earth Smiled]] shows the [[Earth]] and [[Moon]] (bottom-right) from [[Saturn]] (July 19, 2013)]] 
The sky in the upper reaches of [[Saturn]]'s atmosphere is blue (from imagery of the Cassini mission at the time of its [[Cassini retirement|September 2017 demise]]), but the predominant color of its cloud decks suggests that it may be yellowish further down. Observations from spacecraft show that seasonal smog develops in Saturn's southern hemisphere at its perihelion due to its axial tilt. This could cause the sky to become yellowish at times. As the northern hemisphere is pointed towards the Sun only at aphelion, the sky there would likely remain blue. The [[rings of Saturn]] are almost certainly visible from the upper reaches of its atmosphere. The rings are so thin that from a position on Saturn's equator, they would be almost invisible. However, from anywhere else on the planet, they could be seen as a spectacular arc stretching across half the celestial hemisphere.<ref name="bagenal" />

[[Delta Octantis]] is the south pole star of [[Saturn]]. Its north pole is in the far northern region of [[Cepheus (constellation)|Cepheus]], about six degrees from Polaris.

===The sky of Titan===
[[File:Huygens surface color.jpg|thumb|200px|right|Surface of Titan as viewed by the ''[[Huygens (spacecraft)|Huygens]]'' probe]]
[[Titan (moon)|Titan]] is the only moon in the Solar System to have a thick atmosphere. Images from the [[Huygens probe|''Huygens'']] probe show that the Titanean sky is a light tangerine color. However, an astronaut standing on the surface of Titan would see a hazy brownish/dark orange color. As a consequence of its greater distance from the Sun and the opacity of its atmosphere, the surface of Titan receives only about {{frac|3000}}{{citation needed|date=September 2019}} of the sunlight Earth does – daytime on Titan is thus only as bright as twilight on the Earth. It seems likely that Saturn is permanently invisible behind orange smog, and even the Sun would be only a lighter patch in the haze, barely illuminating the surface of ice and methane lakes. However, in the upper atmosphere, the sky would have a blue color and Saturn would be visible.<ref>{{cite web |url=http://www.beugungsbild.de/huygens/povray/titan_rendered.html |title=POV-Ray renderings of Huygens descending to Titan |first=René |last=Pascal |website=www.beugungsbild.de }}</ref> With its thick atmosphere and methane rain, Titan is the only celestial body other than Earth upon which [[rainbow]]s on the surface could form. However, given the extreme opacity of the atmosphere in visible light, the vast majority would be in the infrared.<ref>{{cite web |title=Rainbows on Titan |work=[[NASA]] |url=https://science.nasa.gov/science-news/science-at-nasa/2005/25feb_titan2/ |date=February 25, 2005 |access-date=8 October 2011 |archive-date=October 21, 2011 |archive-url=https://web.archive.org/web/20111021214207/http://science.nasa.gov/science-news/science-at-nasa/2005/25feb_titan2/ |url-status=dead }}</ref>

==Uranus==
From a vantage above the clouds on Uranus, the sky would probably appear dark blue.{{Citation needed|date=May 2023}} It is unlikely that the planet's rings can be seen from the upper atmosphere, as they are very thin and dark. Uranus has a northern polar star, [[Sabik]] (η Ophiuchi), a magnitude 2.4 star. Uranus also has a southern polar star, [[15 Orionis]], a magnitude 4.8 star. Both are fainter than Earth's [[Polaris]] (α Ursae Minoris), although Sabik only slightly.<ref name="bagenal" />

==Neptune==
[[File:Neptunian sky.jpg|thumb|200px|right|Triton in the sky of Neptune (simulated view)]]
The north pole of [[Neptune]] points to a spot midway between [[Gamma Cygni|Gamma]] and [[Delta Cygni]]. Its south pole star is [[Gamma Velorum]].

Judging by the color of its atmosphere, the sky of Neptune is probably an [[Azure (color)|azure or sky blue]], similar to Uranus's. As in the case of Uranus, it is unlikely that the planet's rings can be seen from the upper atmosphere, as they are very thin and dark.

Aside from the Sun, the most notable object in Neptune's sky is its large moon [[Triton (moon)|Triton]], which would appear slightly smaller than a full Moon on Earth. It moves more swiftly than the Moon, because of its shorter period (5.8 days) compounded by its [[retrograde orbit]]. The smaller moon [[Proteus (moon)|Proteus]] would show a disk about half the size of the full Moon. Surprisingly, Neptune's small inner moons all cover, at some point in their orbits, more than 10′ in Neptune's sky. At some points, Despina's angular diameter rivals that of Ariel from Uranus and Ganymede from Jupiter. Here are the angular diameters for Neptune's moons (for comparison, Earth's moon measures on average 31′ for terrestrial observers): Naiad, 7–13′; Thalassa, 8–14′; Despina, 14–22′; Galatea, 13–18′; Larissa, 10–14′; Proteus, 12–16′; Triton, 26–28′. An alignment of the inner moons would likely produce a spectacular sight. Neptune's largest outer satellite, [[Nereid (moon)|Nereid]], is not large enough to appear as a disk from Neptune, and is not noticeable in the sky, as its brightness at full phase varies from magnitude 2.2–6.4, depending on which point in its eccentric orbit it happens to be. The other irregular outer moons would not be visible to the naked eye, although a dedicated telescopic observer could potentially spot some at full phase.

As with Uranus, the low light levels cause the major moons to appear very dim. The brightness of Triton at full phase is only −7.11, despite the fact that Triton is more than four times as intrinsically bright as Earth's moon and orbits much closer to Neptune.

===The sky of Triton===
[[File:Tritonian sky.jpg|thumb|150px|left|Neptune in the sky of Triton (simulated view)]]
[[Triton (moon)|Triton]], Neptune's largest moon, has a hazy atmosphere composed primarily of nitrogen. Because Triton orbits with [[synchronous rotation]], Neptune always appears in the same position in its sky. Triton's rotation axis is inclined 130° to Neptune's orbital plane and thus points within 40° of the [[Sun]] twice per Neptunian year, much like Uranus's. As Neptune orbits the Sun, Triton's polar regions take turns facing the Sun for 82 years at a stretch, resulting in radical seasonal changes as one pole, then the other, moves into the sunlight.

Neptune itself would span 8 degrees in Triton's sky, though with a maximum brightness roughly comparable to that of the full moon on Earth it would appear only about {{frac|256}} as bright as the full moon, per unit area. Due to its eccentric orbit, [[Nereid (moon)|Nereid]] would vary considerably in brightness, from fifth to first magnitude; its disk would be far too small to see with the naked eye. [[Proteus (moon)|Proteus]] would also be difficult to resolve at just 5–6 arcminutes across, but it would never be fainter than first magnitude, and at its closest would rival [[Canopus]].
{{clear}}

==Trans-Neptunian objects==
A [[trans-Neptunian object]] is any minor planet in the Solar System that orbits the Sun at a greater average distance (semi-major axis) than Neptune, 30 astronomical units (AU).

===Pluto and Charon===
[[Pluto]], accompanied by its largest moon [[Charon (moon)|Charon]], orbits the Sun at a distance usually outside the orbit of [[Neptune]] except for a twenty-year period in each orbit.

From Pluto, the Sun is point-like to human eyes, but still very bright, giving roughly 150 to 450 times the light of the full Moon from Earth (the variability being due to the fact that Pluto's orbit is highly elliptical, stretching from just 4.4 billion km to over 7.3 billion km from the Sun).<ref>{{cite web |url=http://blogs.discovermagazine.com/badastronomy/2012/03/15/bafact-math-how-bright-is-the-sun-from-pluto/ |title=BAFact math: How bright is the Sun from Pluto? |last=Plait |first=Phil |date=15 March 2012 |publisher=Discover Magazine |access-date=6 July 2015 |archive-date=July 7, 2015 |archive-url=https://web.archive.org/web/20150707045843/http://blogs.discovermagazine.com/badastronomy/2012/03/15/bafact-math-how-bright-is-the-sun-from-pluto/ |url-status=dead }}</ref> Nonetheless, human observers would notice a large decrease in available light: the solar illuminance at Pluto's average distance is about 85 [[lux#Illuminance|lx]], which is equivalent to the lighting of an office building's hallway or restroom.

Pluto's atmosphere consists of a thin envelope of nitrogen, methane, and carbon monoxide gases, all of which are derived from the ices of these substances on its surface. When Pluto is close to the Sun, the temperature of Pluto's solid surface increases, causing these ices to sublimate into gases. This atmosphere also produces a noticeable blue haze that is visible at sunset and possibly other times of the Plutonian day.<ref>{{Cite web|url=https://www.newscientist.com/article/dn28309-new-horizons-shows-pluto-sporting-blue-skies-and-red-water-ice/|title=New Horizons shows Pluto sporting blue skies and red water ice|website=New Scientist|accessdate=6 October 2023}}</ref>

Pluto and Charon are [[Tidal locking|tidally locked]] to each other. This means that Charon always presents the same face to Pluto, and Pluto also always presents the same face to Charon. Observers on the far side of Charon from Pluto would never see the dwarf planet; observers on the far side of Pluto from Charon would never see the moon. Every 124 years, for several years it is mutual-eclipse season, during which Pluto and Charon each alternately eclipse the Sun for the other at intervals of 3.2 days. Charon, as seen from Pluto's surface at the sub-Charon point, has an angular diameter of about 3.8°, nearly eight times the Moon's angular diameter as seen from Earth and about 56 times the area. It would be a very large object in the night sky, shining about 8%<ref group="nb">Charon's radius is 606 km to the Moon's 1737 (surface ratio 0.12), its albedo is 0.35 to the Moon's 0.14 (2.6 ratio), its semi-major axis is 19591 km to the Moon's 384,400 (385 ratio of illumination), and the Sun is 39.482 times farther (0.00064 ratio of solar illumination). Multiplying these together yields an illuminance 0.077 times the Moon's.</ref> as bright as the Moon (it would appear darker than the Moon because its lesser illumination comes from a larger disc). Charon's illuminance would be about 14 mlx (for comparison, a moonless clear night sky is 2 mlx while a full Moon is between 300 and 50 mlx).
<gallery class="center">
File:Plutonian system.jpg|View from [[Hydra (moon)|Hydra]]. [[Pluto]] and [[Charon (moon)|Charon]] (right); [[Nix (moon)|Nix]] (left) (artist concept).
File:ESO-L. Calçada - Pluto (by).jpg|View from Pluto. [[Sun]] (right-top); [[Charon (moon)|Charon]] (left) (artist concept).
File:PIA19682-Pluto-Charon-Sun-ArtistConcept-20150608.jpg|View from Pluto of Charon and the Sun (artist concept).
File:NH-PlutoByMoonlight-ArtistConcept-20150710.jpg|Pluto by moonlight<br />(artist concept).
</gallery>
{{multiple image|vertical
| caption_align     = center
| header_align      = center
| align             = center
| header            = 
| direction         = vertical
| width             = 600
| image1            = <!---PIA19948-NH-Pluto-Norgay-Hillary-Mountains-2050714.jpg--->
| width1            = 
| caption1          = 
| image2            = PIA19947-NH-Pluto-Norgay-Hillary-Mountains-20150714.jpg
| width2            = 
| caption2          = 
| footer_align      = center
| footer            = [[Pluto]] – [[Tenzing Montes]] (left-foreground); [[Hillary Montes]] (left-skyline); [[Sputnik Planitia]] (right)<br />Near-sunset view includes several layers of [[Atmosphere of Pluto|atmospheric haze]].
}}

==Extrasolar planets==
{{Original research section|date=April 2013}}
For observers on [[extrasolar planet]]s, the [[constellation]]s would differ depending on the distances involved. The view of outer space of [[exoplanets]] can be extrapolated from open source software such as [[Celestia]] or [[Stellarium (software)|Stellarium]]. Due to [[parallax]], distant stars change their position less than nearby ones. For alien observers, the Sun would be visible to the [[naked eye|naked human eye]] only at distances below 20<ref name="SIMBAD-mag6.5">{{cite web |title=Vmag<6.5 |publisher=SIMBAD Astronomical Database |url=http://simbad.u-strasbg.fr/simbad/sim-sam?Criteria=Vmag%3C6.5 |access-date=26 June 2010 }}</ref> – 27<ref name="Bortle">{{cite web |date=February 2001 |title=The Bortle Dark-Sky Scale |publisher=Sky & Telescope |first=John E. |last=Bortle |url=http://www.skyandtelescope.com/resources/darksky/3304011.html |access-date=18 November 2009 |archive-date=March 23, 2009 |archive-url=https://web.archive.org/web/20090323232806/http://www.skyandtelescope.com/resources/darksky/3304011.html |url-status=dead }}</ref> [[parsec]] (60–90 [[light year|ly]]).<ref group="nb">These numbers are extrapolated from the fact that the human eye can generally see up to magnitude 6.5 on [[Earth]], while it can see up to magnitude 7 under the best possible conditions.</ref> If the Sun were to be observed from another star, it would always appear on the opposite coordinates in the sky. Thus, an observer located near a star with [[right ascension|RA]] at 4 [[minute of arc|hr]] and [[declination]] −10 would see the Sun located at RA: 16 hr, dec: +10. A consequence of observing the universe from other stars is that stars that may appear bright in our own sky may appear dimmer in other skies and vice versa.

In May 2017, glints of light from [[Earth]], seen as twinkling by [[DSCOVR]], a satellite stationed roughly a million miles from Earth at the Earth-Sun L1 [[Lagrange point]], were found to be [[Reflection (physics)|reflected light]] from [[ice crystals]] in the [[Atmosphere of Earth|atmosphere]].<ref name="NYT-20170519">{{cite news |last=St. Fleur |first=Nicholas |title=Spotting Mysterious Twinkles on Earth From a Million Miles Away |url=https://www.nytimes.com/2017/05/19/science/dscovr-satellite-ice-glints-earth-atmosphere.html |date=19 May 2017 |work=The New York Times |access-date=20 May 2017 }}</ref><ref name="GRL-201760515">{{cite journal |last1=Marshak |first1=Alexander |last2=Várnai |first2=Tamás |last3=Kostinski |first3=Alexander |title=Terrestrial glint seen from deep space: oriented ice crystals detected from the Lagrangian point |date=15 May 2017 |journal=[[Geophysical Research Letters]] |volume=44 |issue=10 |pages=5197–5202|doi=10.1002/2017GL073248 |bibcode = 2017GeoRL..44.5197M |s2cid=109930589 |url=https://zenodo.org/record/1229066 |hdl=11603/13118 |hdl-access=free }}</ref> The technology used to determine this may be useful in studying the atmospheres of distant worlds, including those of [[exoplanet]]s.

The position of stars in extrasolar skies differs the least to the positions in Earth's sky at the [[List of nearest stars and brown dwarfs|closest stars to Earth]], with nearby stars shifting position the most.
The Sun would appear as a bright star only at the closest stars. At the [[Alpha Centauri]] [[star system]] the Sun would appear as a bright star continuing the wavy line of [[Cassiopeia (constellation)|Cassiopeia]] eastward, while [[Sirius]] would shift to a position just next to [[Betelgeuse]] and its own [[Proxima Centauri]] [[red dwarf]] would still appear as a dim star contrary to its main A and B stars.<ref name="Drew Ex Machina 2020">{{cite web | title=Alien Skies: The View from Alpha Centauri | website=Drew Ex Machina | date=2020-08-28 | url=https://www.drewexmachina.com/2020/08/28/alien-skies-the-view-from-alpha-centauri/ | access-date=2023-02-22}}</ref> At [[Barnard's star]] the Sun would appear between the not much shifted Sirius and [[Belt of Orion]] compared to in the sky of Earth. Conversely the Sun would appear from Sirius and also [[Procyon]] around [[Altair]].<ref>{{cite web | title=See the Sun from Other Stars | website=Sky & Telescope | date=2022-02-02 | url=https://skyandtelescope.org/astronomy-blogs/explore-night-bob-king/see-the-sun-from-other-stars/ | access-date=2023-02-22}}</ref>

Planets of the [[TRAPPIST-1]] system orbit extremely close together, enough so that each planet of the system would provide a detailed view of the other six. Planets of the TRAPPIST-1 system would appear in the sky with angular diameters comparable to the moon as viewed from Earth. Under clear viewing conditions, details such as phases and surface features would be easily visible to the naked eye.<ref>{{cite web | title=10 Things: All About TRAPPIST-1 | website=solarsystem.nasa.gov | date=2018-02-20 | url=https://solarsystem.nasa.gov/news/335/10-things-all-about-trappist-1/ | access-date=2023-04-29}}</ref>

==From the Large Magellanic Cloud==
From a viewpoint in the LMC, the Milky Way's total [[apparent magnitude]] would be −2.0—over 14 times brighter than the LMC appears to us on Earth—and it would span about 36[[degree (angle)|°]] across the sky, the width of over 70 full moons. Furthermore, because of the LMC's high [[Galactic coordinate system|galactic latitude]], an observer there would get an oblique view of the entire galaxy, free from the interference of [[interstellar dust]] that makes studying in the Milky Way's plane difficult from Earth.<ref group="nb">Some of the figures in the "View" section were extrapolated from data in the Appendix of Chaisson and McMillan's ''Astronomy Today'' (Englewood Cliffs: Prentice-Hall, Inc., 1993).</ref> The [[Small Magellanic Cloud]] would be about magnitude 0.6, substantially brighter than the LMC appears to us.

==See also==
* [[Exosphere]]
* [[Pole star#Other planets|Pole star § Other planets]]
* [[Sky]]
* [[Timeline of first images of Earth from space]]

==Notes==
{{Reflist|group=nb}}

==References==
{{Reflist|30em}}

==Further reading==
{{Refbegin}}
*{{cite book |last=Carroll |first=Michael |title=Space art : how to draw and paint planets, moons, and landscapes of alien worlds |year=2007 |publisher=Watson-Guptil Publications |location=New York |isbn=9780823048762 |url-access=registration |url=https://archive.org/details/spacearthowtodra00carr }}
*{{cite book |last=Carroll |first=Michael |title=Drifting on Alien Winds Exploring the Skies and Weather of Other Worlds |year=2010 |publisher=Springer Science+Business Media, LLC |location=New York, NY |isbn=9781441969170 }}
*{{cite magazine |first=Lincoln |last=Barnett |title=The Starry Universe |magazine=Life |date=December 20, 1954 |pages=44–64 |url=https://books.google.com/books?id=WlMEAAAAMBAJ&pg=PA44 |access-date=April 12, 2013 }}
*{{cite book |last=Perelman |first=Yakov |chapter=Lunar heavens |title=Astronomy for entertainment |year=2000 |publisher=University Press of the Pacific |location=Honolulu |isbn=9780898750560 |pages=78–84 }}
{{Refend}}

==External links==
* [http://www.hudsonfla.com/spaceview.htm Astronauts on the planets] 
* [http://www.orionsarm.com/xcms.php?r=oa-page&page=gen_skyonalienworlds Essay on the possible sky colours of alien worlds.]
* [http://space.jpl.nasa.gov/ JPL Solar System Simulator]
* [http://www.boulder.swri.edu/~buie/pluto/chphases.html Phases of Charon as seen from Pluto]
* [https://books.google.com/books?id=WlMEAAAAMBAJ&pg=PA44 The Starry Universe] – [[Life (magazine)|''Life'' magazine]] (December 20, 1954).
* Sunsets simulated on other planets ([[NASA]]; June 22, 2020)
** {{YouTube|5DwLODp1cIY|Video (1:06)}}
** {{YouTube|vrLfHv6sze0|Video (2:59)}}
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