[[caption-width-right:350:[[MyFriendsAndZoidberg Ignore Pluto.]] [[PlutoIsExpendable It's not a planet anymore.]] Also, [[YouCannotGraspTheTrueForm definitely not to Scale]]]]

->'''Mercury''' was near the sun so Janet dropped by - but the mercury on Mercury was much too high.\\
So Janet went to '''Venus''', but on Venus she found: she couldn't see a thing for all the clouds around.\\
'''Earth''' looked exciting, Kind of green and inviting, So Janet thought she'd give it a go. But the creatures on that planet looked so very weird to Janet. She didn't even stop to say "hello".\\
'''Mars''' is red, And '''Jupiter''''s big. '''Saturn''' shows off its rings. '''Uranus''' is built on a funny tilt, And '''Neptune''' is its twin.\\
'''Pluto''', little Pluto is the farthest planet from the sun
-->--''WesternAnimation/SchoolhouseRock'', "[[https://www.youtube.com/watch?v=MGgajx1pGPU Interplanet Janet]]"[[note]]Released before the [=IAU=]'s redefinition of a planet and before the Voyager probes had visited the outer planets, explaining why their descriptions are rather light on info.[[/note]]

The things you can find in our star system. Generally speaking, it consists of a central star, four Earth-type planets, four gas giants, and a large amount of smaller objects, including dwarf planets, moons, asteroids, comets and space junk, mostly clustered in rings around the Sun or other planets.

Despite years and years of ScienceFiction stories about planets around other suns, we actually lacked any real scientific proof of them until the early 1990's when exoplanets were first detected by their wobble on their parent star. Until then, it was quite possible that our solar system was simply a fluke. For example, one theory on the formation of our solar system, "Tidal Theory" - 1917, was that a passing star came close to our sun, drawing a filament of solar matter out of it which coalesced into the planets. Wiki/{{Wikipedia}} has a page on those theories [[https://en.wikipedia.org/wiki/History_of_Solar_System_formation_and_evolution_hypotheses here]] if you are interested.

If you're interested in things in space farther away than our star system, you might wish to consult UsefulNotes/LocalStars. If you're interested in what planets might, or might not, be orbiting other stars, you might wish to consult the more general UsefulNotes page on UsefulNotes/{{Planets}}.

* UsefulNotes/TheSun: The star of the show, literally and figuratively. About 99.9% of all the mass in the Solar system is in the sun. Our Sun is a wonderfully stable one, unusually so even for a G-type, which is beneficial for us. Other stars big and small often emit dangerous-to-life x-ray flares. She has [[BeautyMark the odd sunspot here and there too]], and thank goodness, last time our Sun didn't, we experienced an ice age. Rather than red dwarfs, that shine out mostly infrared light, she emits a lot of light on the visible spectrum, [[ThePowerOfTheSun which is just great for photosynthesising plants]]. She does emit ultraviolet radiation too, [[EmbarrassinglyPainfulSunburn so put on that sunblock before you step outside]]. Sadly, all good things must come to an end. The Sun is already 4.6 billion years old, and when it uses up too much of its Hydrogen reserves, it'll get hotter and hotter, until becoming a humongous Red Giant that'll no doubt swallow up the inner planets along with Earth. [[/index]]
** See {{Heliotropes}} for related tropes.


Most of these and their associated moons are named after characters from Myth/ClassicalMythology; the planets themselves have Roman/Latin names, but the moons are more variable.

!!Terrestrial ("Earth-type") planets
* UsefulNotes/{{Mercury}}: smallest of the planets, closest to the Sun. It is small and very hot (apart from some permanently shadowed craters at the poles which ''may'' contain ice), with [[strike:no]] the merest whisper of an atmosphere. Early scientists believed it to be tide-locked (one side permanently faces the sun), but it turns out it rotates 3 times for every 2 times it circles the sun (which, when combined with an elliptical orbit causes weird effects like "hot" and "cold" poles on the equator, and [[AlienSky the Sun doing a slow loop-the-loop in the sky once each 88-day Mercurian year]]). When ''Mariner 10'' flew by in 1974, it found the planet to be unexpectedly dense; scientists now believe it was originally similar in size and composition to Venus and Earth, but [[EarthShatteringKaboom a massive impact with a leftover planetesimal]] tore away the atmosphere and most of the relatively light mantle, leaving the metal-heavy core behind. Among the inner planets Mercury's orbit is the most unstable and susceptible to Jupiter's gravitational influence.
* UsefulNotes/{{Venus}}: sometimes referred to as Earth's sister planet due to their similar sizes. It has an extremely dense atmosphere (surface pressure is 90 bars, compared to 1 on Earth) and can reach a surface temperature of 470 °C/870 °F (although at the top of Maxwell Montes, almost 7 miles above the average surface level, it's "only" 380 °C/716 °F and 60 bars). The culprit for all this? The greenhouse effect--90 atmospheres of carbon dioxide with some helping of other greenhouse gases will be quite hot. [[note]]"An Estimate of the Surface Temperature of Venus Independent of Passive Microwave Radiometry" by one [[Creator/CarlSagan C. Sagan]] gives it at ~700K in 1967.[[/note]] Volcanoes on Earth have belched out the same amount, [[SealedEvilInACan but it ended up trapped in carbonate rock]]. Venus also started with the same amount of water as the earth had, but it was vaporized (300 atmospheres worth) and created a [[UpToEleven super greenhouse effect]] with temperatures in the ''thousands'' of degrees. [[note]]This plus the slow rotation probably wrecked any chance at plate tectonics; instead of plates constantly sliding against each other, [[LethalLavaLand there seems to be intermittent vulcanism punctuated by extreme periods of volcanic activity replacing much of the surface every billion years or so]].[[/note]] Eventually the water molecules dissociated into hydrogen and oxygen and escaped into space, leaving Venus high and dry. Interestingly, the zone between 50 and 65 kilometers above the surface has pressures and temperatures right around Earth normal. Add to that the fact that an 80/20 nitrogen/oxygen mix would act like a lifting gas and [[Film/TheEmpireStrikesBack Cloud City]] would be right at home. It oddly rotates in the ''opposite direction'' to most other planets. Due to Venus being mythologically associated with femininity, by convention all geographic features there are named after women or female entities, except for Maxwell Montes and Alpha and Beta Regio. [[note]]These features were first detected by ground-based radar in the mid-1960s; Alpha and Beta Regio were the first two terrain features to be isolated, and Maxwell Montes was named after James Clerk Maxwell, the formulator of the theory and equations of electromagnetism that ultimately led to the invention of radar.[[/note]] There is some argument over whether the proper adjective is 'Venusian', 'Venerean', or 'Cytherean'.
* UsefulNotes/{{Earth}} (or in Latin: [[PlanetTerra Terra]]): Mostly considered an InsignificantLittleBluePlanet that despite its status holds [[EarthIsTheCenterOfTheUniverse extreme significance]] for [[PunyEarthlings some carbon-based lifeforms]].
** More seriously, Earth is the 6th most massive solar system object, the largest of the Rocky planets, and the most dense object. It is one of two worlds (or possibly three, with supersalty water on Mars) with liquids on the surface, forming rivers, lakes, and such (The other is Saturn's moon Titan, with methane and ethane as the surface liquids), the only one with life (that we know of), and the only one with plate tectonics. The atmosphere is unique in having a large proportion as free oxygen, which in addition to supporting most life, changes the structure in a number of subtle ways compared to other planets. Earth also generates a magnetic field, unlike Venus and Mars, that is much stronger than that of Mercury but weaker than that of the gas giants. Our world used to have a similar atmosphere with its "twin" Venus, but lost it in the giant impact event.
** UsefulNotes/TheMoon: Our nearest neighbor, and the only celestial body beyond Earth that has been explored by humans in person ([[UsefulNotes/ConspiracyTheories allegedly]]). It is theorized that the Moon is the left over debris from [[EarthShatteringKaboom a giant impact event]] with a proto-Earth and a Mars' sized object called Theia.
* UsefulNotes/{{Mars}}: Albedo features identified in the 19th century led to manic speculation about the potential presence of life. Today we know it's not very lively, but that doesn't make it any less interesting. It's still a favorite for space exploration, with a handful of unmanned probes sent there every two years. There are currently five working orbiters around it (''2001 Mars Odyssey'', ''Mars Express'', ''Mars Reconnaissance Orbiter'', ''MAVEN'', and ''Mangalyaan''), [[note]]Respectively sent by UsefulNotes/{{NASA}}, UsefulNotes/{{ESA}}, NASA, NASA, and ISRO (the last being India, for those not up on their space agencies)[[/note]] and two working landers on it (''Opportunity'' and ''Curiosity'').

!! Gas giants
* UsefulNotes/{{Jupiter}}: The largest of them all, and thus fittingly named after the Roman God of Gods. Of course, [[OlderThanTheyThink the Romans named it that long before they had any idea just how big it was]]. Jupiter is ''vast'', often referred to as a "failed brown dwarf" and while not as dense as Earth, it has a magnetic field some 20,000 times stronger than our world does. Jupiter is... ''odd'', and by extension makes our solar system unusual. Gas giants have the tendency to migrate inwards towards their stars, becoming "hot jupiters". This happened in our system, and it would have come in like a wrecking ball... until the formation of Saturn. Saturn pulled Jupiter outwards, allowing the rocky terrestrial worlds to form. Jupiter has been described as a cosmic vacuum [[BigBrotherInstinct protecting us from comets and other asteroids]] that would otherwise [[TheEndOfTheWorldAsWeKnowIt obliterate all life on Earth]].
** UsefulNotes/TheMoonsOfJupiter: Simon Marius and Galileo Galilei each had claims to the discovery of the first four. Though discovery credit ultimately went to Galileo (and thus, they are known as the Galilean satellites), Marius's names were ultimately used (from innermost out: Io, Europa, Ganymede and Callisto). All the others are named for the daughters and lovers of either Jupiter or his Greek counterpart, Zeus.
* UsefulNotes/{{Saturn}}: Well known for its spectacular ring system. Its average density is less than that of water[[note]]so if you were to put it in a tub of water, it would float[[/note]], and despite its bland butterscotch appearance it has storms that rival any found on Jupiter. Plus it has [[http://en.wikipedia.org/wiki/Saturn#North_pole_hexagonal_cloud_pattern a polar hexagon]]. How cool is that?
** UsefulNotes/TheMoonsOfSaturn: Originally named after Roman deities associated with harvests (Saturn itself is named after the Roman god of agriculture). When they ran out (Saturn, it turns out, has ''[[{{Understatement}} a lot of moons]]''), they switched to Giants from various mythologies. Norse ice giants are used for newly-discovered moons beyond Phoebe.
** [[http://en.wikipedia.org/wiki/Rings_of_Saturn The Rings of Saturn]]
* UsefulNotes/{{Uranus}}: It had been detected by astronomers as early as 1690[[note]]John Flamsteed thought it was a star and named it "34 Tauri"; that designation was therefore available for [[Creator/JossWhedon a certain talespinner]] to apply to [[{{Series/Firefly}} the star system at the heart of his one of his 'Verses]].[[/note]], but Sir William Herschell actually identified it as a planet in 1789. It is named after the Greek god of the sky.[[note]]Yes, really, [[UranusIsShowing you adolescents]].[[/note]] It's 4 times the diameter of the Earth, which is still less than half the diameter of Jupiter. Seen as minty green in color observed from Earth by early telescopes, close-up observation showed it's more pale blue. It's denser than Jupiter and Saturn with a higher proportion of methane, ammonia and water. Uranus is even colder than Neptune. Voyager 2 passed by it in 1986 and observed few distinct clouds, [[ScienceMarchesOn but later observations from Earth have revealed more]]. It has a set of coal-black rings (discovered in 1977) and is tilted 98 degrees on its axis--each pole spends 42 years in light and 42 in darkness. Scientists have reason to believe it's on its unique side-ways tilt due to a massive impact that depleted its internal core temperature. Also known for being the planet which the ''[[Franchise/StarTrek Enterprise]]'' circles while [[UranusIsShowing wiping out Klingons]].
** UsefulNotes/TheMoonsOfUranus (The Bard [[foldercontrol]]

[[folder: In Space ]]
): Fittingly for an English-discovered planet, Uranus' moons are all named after characters from Creator/WilliamShakespeare. Two of the original five received names from Creator/AlexanderPope's ''Literature/TheRapeOfTheLock''.
* UsefulNotes/{{Neptune}}: Discovered in 1846 by three different astronomers (John Couch Adams of the UK and Urban Leverrier of France predicted its location independently based on changes in the orbit of Uranus, and Johann Gottfried Galle of Germany found it based on Leverrier's data). Note, however, [[OlderThanTheyThink that Galileo actually observed Neptune twice in the winter of 1612–13]], but merely noted that it appeared to move and never followed up. Watery blue in color, befitting a planet named for the Roman god of the seas; its composition is similar to that of Uranus. Voyager 2 detected some noticeable cloud features when it flew by in 1989, including the "Great Dark Spot" which is an almost perfect analogue to Jupiter's Great Red Spot, other than being shorter-lived; it disappeared sometime in the next five years, but a new one appeared in the northern hemisphere some years after that. It has an unstable ring system that clumps into arcs at some longitudes. From 1979 to 1999 it was further away from the Sun than Pluto, and with a nearly 165-year-long orbital period it has only completed one orbit since its discovery--and that in 2010.
** UsefulNotes/TheMoonsOfNeptune (Greek deities associated with water)
* Last but not least, in January 2016 a group of astronomers have suggested that the eccentric orbits of several large Kuiper Belt Objects (see the Detached Object category of small solar system bodies listed further down) could be explained by the presence of [[https://en.wikipedia.org/wiki/Planet_Nine a ninth planet]] (so-called [[ExactlyWhatItSaysOnTheTin Planet Nine]]), that would be a bit smaller in mass than Neptune or Uranus, two to four times larger than Earth, and that would orbit the Sun in a highly eccentric and inclined orbit that would take many thousands of years to complete never approaching at less than around seven times the Sun-Neptune distance[[note]]At its farthest, Neptune is 30-something AU away from the sun; Planet's Nine's nearest distance to the sun is predicted to be about ''200 AU''[[/note]]. Please note, however, that despite the claims of "a new planet discovered" there's at best just indirect proof of its existence and it's an entirely hypothetical object until it's finally imaged[[note]]Not something that will be easy, mind you, with ''millions'' of stars and galaxies of similar brightness to that planet if it existed at all[[/note]].

!!Dwarf Planets

The reason behind the introduction of this category of celestial bodies was a discovery of several Kuiper Belt Objects that rivaled or exceeded [[PlutoIsExpendable Pluto]] in size and thus strained the definition of planet. It was decided that it'd be simpler to demote Pluto than to make all of them planets--[[OlderThanTheyThink a similar course of events took place after the discovery of the four largest members of the asteroid belt in the 19th century]]. It, rather expectedly, ended in a massive FlameWar among not just enthusiasts of astronomy, but astronomers themselves. For this reason, one of the planets that precipitated the kerfuffle was appropriately named for Eris, the Goddess of Discord.[[note]]Mike Brown deliberately named it that knowing that by asking the International Astronomical Union to officially declare it a planet would cause a ''lot'' of discord.[[/note]]

To qualify as a dwarf planet, or "plutino", the object must be big enough that its own gravity has pulled it into a more-or-less round shape. (It also can't be orbiting another planet, since then it would be a moon.) Even beyond the Pluto issue, the concept of dwarf planets is controversial among astronomers because of both the relatively arbitrary distinction between a dwarf planet and a planet[[note]]By some interpretations, ''Neptune'', the third largest planet, would not fit the new definition of a planet, since it has failed to sweep objects such as Pluto and Eris out of its orbit. However, this is a misunderstanding of the term; "Clearing the Neighborhood" also accounts for smaller bodies being locked into an orbital resonance where they are still controlled by the planet without directly orbiting it, which is exactly what Neptune did to everything that it did not expel or capture, Pluto included.[[/note]], and because the terminology is inconsistent (i.e. a dwarf star is ''always'' a ''type'' of star rather than a separate category, so how would a dwarf planet not be a type of planet?).

The term "clearing the neighborhood" is the biggest source of confusion to laypeople; even astronomers who support the current definition generally think it's a clunky term and that something like "gravitational dominance" or "dynamic dominance" would be more appropriate. A sufficiently massive object will have three effects on the debris in its orbit. The first is that any objects will be captured and become moons. This is the least likely of the three effects to happen. The second effect, and the one most frequently thought of when people hear "clear the neighborhood" is expulsion: small bodies will be launched into eccentric orbits or out of the solar system entirely. The third, and most frequently misunderstood, is that any small bodies that are not captured or expelled will be locked in an orbital resonance. Neptune and Pluto are a prime example: every time Neptune completes three full revolutions around the sun, Pluto completes two. It was discovered in the 1990s that Pluto is the largest of many objects that were locked into such a relationship with Neptune. Other examples include the Trojan Asteroids that inhabit the regions governed by Earth, Mars, and Jupiter. In short, a small object does not need to directly orbit a major planet to be controlled by its gravity. Where major planets control entire regions, dwarf planets only control their moons at best.

To date, only 5 dwarf planets are known, with another forty or so pending confirmation:

* [[http://en.wikipedia.org/wiki/Pluto_(dwarf_planet) Pluto]]–[[http://en.wikipedia.org/wiki/Charon_(moon) Charon]][[note]](along with four smaller moons--Nix, Hydra, Kerberos, and Styx)[[/note]][[note]]Charon's status is itself a subject of debate. It is currently classified as Pluto's largest natural satellite, but the IAU has yet to clearly define what a natural satellite is. Some argue that because the Pluto-Charon barycenter lies in the empty space between the two bodies, Charon should be classified as a dwarf planet.[[/note]]
* [[http://en.wikipedia.org/wiki/Haumea_(dwarf_planet) Haumea]][[note]](it has two moons--Hi'iaka and Namaka)[[/note]]
* [[http://en.wikipedia.org/wiki/Makemake_(dwarf_planet) Makemake]]
* [[http://en.wikipedia.org/wiki/Eris_(dwarf_planet) Eris]][[note]](it is accompanied by a single known moon, Dysnomia)[[/note]][[note]]When first discovered, it was nicknamed [[Series/XenaWarriorPrincess Xena]]. No, Dysnomia was never referred to in any official context as "[[{{Sidekick}} Gabrielle]]".]][[/note]]

All these are dark and freezing cold, absolutely no life (except for, probably, [[Creator/HPLovecraft Mi-go]]) could exist or survive here.

* [[http://en.wikipedia.org/wiki/Ceres_(dwarf_planet) Ceres]], the biggest in the asteroid belt, and the only main-belt asteroid big enough to qualify as a dwarf planet. It - along with the asteroids Pallas, Juno, and Vesta - was also the first "planet" to be demoted, similarly to Pluto, but it was first called an asteroid before the class of dwarf planets was invented for Pluto. Apparently some sources still classify it as an asteroid. It looks at first, by the way, as the typical celestial object pockmarked by ''lots'' of craters... until you look closer and find mysterious white spots on some of them, at least one of which have occasional hazes over it, as well as one big pyramid-shaped mountain with a height of 3 miles. Currently[[note]]And will keep so for centuries[[/note]] orbited by the ''Dawn'' spacecraft.

!Everything Else
* [[http://en.wikipedia.org/wiki/Asteroid_belt The Asteroid Belt]]: Also known as the Piazzi Belt (after the discoverer of Ceres) to distinguish it from the Kuiper Belt, it can be found between Mars and Jupiter. It's not an AsteroidThicket--the belt's combined mass is only 4% of the Moon's, it's spread out over a volume of space bigger than Earth's entire orbital disc, and a full third of that mass is Ceres, so unmanned spacecraft generally pass through it without incident.
* [[http://en.wikipedia.org/wiki/Comet Comets]]
** [[http://en.wikipedia.org/wiki/Comet_Halley Halley's Comet]]: The best-known of all comets, because it's large enough to be seen from Earth and (unlike most large-ish comets) has an orbital period short and predictable enough that the average human has at least one opportunity in their lifetime to see it.
* [[http://en.wikipedia.org/wiki/Kuiper_belt The Kuiper Belt]]: Named after astronomer Gerard P. Kuiper, who theorized its existence in 1951. Also known as the Edgeworth-Kuiper Belt.
* [[http://en.wikipedia.org/wiki/Scattered_disc The Scattered Disc]]
* [[https://en.wikipedia.org/wiki/Detached_object Detached Objects]]
** [[https://en.wikipedia.org/wiki/90377_Sedna Sedna]]: Almost certainly the sixth dwarf planet. Its orbit is so distant that it never comes within 46 AU of Neptune (which for the record is more than 1.5 times distance between Neptune and the sun) and thus no planet's gravity exerts any influence on it. Its orbit is also extremely elliptical (its closest approach to the sun is 76 AU while the furthest it gets is 936 AU), something that is normally caused by interaction with Neptune and thus causing renewed speculation that a large planet must exist beyond Neptune's orbit. Its orbital period is estimated to be ''11,400 years'', while it's only physically observable from Earth for 25 years of its orbit. This means astronomers were ''very'' lucky to find it.
* [[http://en.wikipedia.org/wiki/Oort_cloud The Oort Cloud]]: Named after astronomer Jan Oort.

The differences between the last four can be contentious. The Kuiper Belt mostly consists of objects locked into orbital resonance with Neptune. Pluto, along with many other objects known as "plutinos", is locked into a 3:2 resonance. Another class of objects, called "twotinos", are locked into a 2:1 resonance, and other, more arcane resonances exist. The scattered disc consists of objects pushed further out into space by Neptune's outward migration (relatively early in the life of the Solar System); Eris and several other dwarf planets are located here. The Oort cloud consists of objects upon which Neptune's gravity has little significant effect. The Detached Objects are trans-Neptunian bodies that are too close to the sun to be part of the Oort Cloud, yet too far away for Neptune to be responsible for their eccentric orbits. Since the dividing line for all four is the historical gravitational effect of another astronomical object, one really can't say "at XX AU, the Kuiper belt ends and the scattered disc begins."

The naming of minor Sun-orbiting objects in the Solar System depends on location. Objects in the Main Asteroid Belt are given names from Greek mythology. Objects in the same orbit as Jupiter (the Trojan asteroids) are given names associated with the Trojan War. Objects in similar orbits to Pluto (the "Plutoids") are named after deities of the underworld. Kuiper Belt objects (other objects beyond Neptune's or Pluto's orbits) are named after deities of creation that are ''not'' Greek or Roman. An exception was made for Eris due to its brief stint as the "tenth planet".

Turning to nomenclature on a smaller scale, the New Horizons probe reached Pluto and Charon in July 2015, giving cartographers at least two whole new worlds worth of craters, mountains, and other points of interest to name. Current plans are to name features after various underworld locations and their denizens, spacecraft and space scientists, explorers and their vessels (real and fictional), and artists and authors whose works have depicted exploration. [[http://www.ourpluto.org/ A page has been set up]] to allow people to vote for names to be submitted to the IAU for official use, so cast your vote for a real-life [[Series/{{Firefly}} Vallis Serenity]], [[Literature/WatershipDown Colles Watership]], and [[Series/BabylonFive Regio Z'ha'dum]]! [[note]]sorry, [[Franchise/StarTrek Trekkers]], but [[http://planetarynames.wr.usgs.gov/Feature/15133?__fsk=1962724877 there's already an Enterprise Rupes]] on Mercury.[[/note]][[note]]Sorry, voting was closed back on 24 April 2015[[/note]]

The official IAU definition for fictional names of features on Pluto is items from global underworld mythos, leading to the use of [[Series/TheLordOfTheRings Balrog Macula]] and [[Creator/HPLovecraft Cthulhu Regio]]. Most features are named for real astronomers (Tombaugh Regio, a.k.a. "Pluto's Heart"), real explorers (Hillary Montes and Norgay Montes), and real spacecraft (Sputnik Planum, Voyager Terra).

The official IAU definition for fictional names of features on Charon is items and milestones of "fictional space".[[note]]Charon ''was'' discovered in 1978, which was arguably the heyday of science fiction on TV.[[/note]] With that one, the ''New Horizons'' team is really going to town. [[Franchise/StarTrek Vulcan Planum]] (with [[Creator/LeonardNimoy Spock Crater]]), [[Series/DoctorWho Gallifrey Macula]], [[Franchise/{{Alien}} Ripley Crater and Nostromo Chasma]], Manga/{{Macross}} and [[Series/{{Firefly}} Serenity Chasmae]], [[Franchise/StarWars Organa, Skywalker and Vader Craters]]...

!Interplanetary distances

Most popular depictions of the Solar system, even in science classes, tend to emphasize the relative sizes of the sun and planets and gloss over the scale of the immense distances between them. This can lead to embarrassing instances of SciFiWritersHaveNoSenseOfScale.

Look at the page image for ConvenientlyClosePlanet. That's just the Earth–moon system to scale. The planets are much, much farther apart than this.

If the sun were the size of a bowling ball, the Earth would be roughly the size of a peppercorn, and the distance between them would be nearly ''25 meters''. Jupiter would be the size of a walnut (still in its shell), and would be over ''120'' meters from the sun-bowling-ball. Saturn would be another walnut at 230 meters from the bowling ball, Uranus would be a peanut 450 meters from the bowling ball, and Neptune would be another peanut a whopping 700 meters from the bowling ball (that's nearly ''half a mile'' away from it). Light (remember, the fastest thing in the Universe and whose velocity cannot be exceeded) at this scale would move [[SarcasmMode at the impressive speed]] of ''166 meters per hour'', and just try to imagine the speed of our current interplanetary probes at that scale[[note]]Or don't: the ''Voyager 1'' probe was launched in 1977. It passed Neptune ''12 years later'', traveling at the incredibly fast (by human standards) 11 miles per ''second''. As an aside, Voyager 1 officially passed out of the sun's sphere of influence (the heliosphere) in 2013, ''36 years'' after being launched.[[/note]].
Series/{{Bill Nye|TheScienceGuy}} demonstrates this scale with an exhausting bicycle ride in [[http://www.youtube.com/watch?v=97Ob0xR0Ut8 this video]]. [[note]]And just for completion, Proxima Centauri--the closest star to the Sun--would be a walnut slightly larger than the one used to represent Jupiter, ''at more than 6100 kilometers away''.[[/note]]

You'll often hear, particularly when concerning the ''Voyager'' probes, that they have reached the "edge" of the Solar System; originally this meant moving beyond Pluto's orbit, a definition that now feels very "last century". Now, it generally means when the "atmosphere" generated by the Sun is pushed back by the atmosphere of interstellar space (a point called the heliopause). And while yes, the space beyond the heliopause is technically the same as the space between stars, it is NOWHERE NEAR the edge of the Sun's gravitational influence, which is a thousand times farther out. In fact, the Sun's influence doesn't "end". Rather, it merges with its closest neighbors, including Alpha Centauri. In other words, you're not out of the Solar System til you're in another one.

!Past and future

The Solar System was born more or less four thousand and a half billion years ago from the collapse of a large gas cloud, that as typical per the process of star formation fragmented into many smaller ones[[note]]There's strong evidence that one or several supernovae, the deaths of massive star, may have triggered this proces. It, as well as others, show that our Sun was born in a large star-forming region of the style of the [[https://en.wikipedia.org/wiki/Orion_Nebula Orion nebula]], forming part of a large star cluster (imagine the [[AlienSky star-studded sky in that epoch]]. Its brothers and sisters are somewhere in the Milky Way, perhaps even with planets where life has developed too[[/note]]. One of said fragments, as it collapsed, began spin faster flattening and taking a flying saucer-like shape. Its center, as it collapsed, became hotter and denser until hydrogen fusion began at its very center. The Sun was born[[note]]Our daystar was during those early epochs a very different one: larger, cooler, and more luminous during its contraction, covered by sunspots, and more active with strong flare activity. When hydrogen ignited, while less luminous than now, it kept said activity with sunspots and flares galore and a ''very'' powerful solar wind until a few million years later it calmed somewhat, especially said wind.[[/note]]

While that happened in the center, things were considerably more active in the surrounding disk. While the countless grains of matter that formed it were in full FusionDance forming larger ones that would fuse to form even larger ones and so on, the heat of the contracting core vaporized low-melting point compounds as water or methane and the like of those coalescing bodies too close, that were able to condense only further out, meaning the inner Solar System would be composed of low-mass (proto)planets formed of metal and rocks. In the outside, with those volatile compounds safe from vaporization, things happened at a considerably faster pace and much larger core bodies formed that began to accrete gas from the surrounding in a runaway process that stopped both by the disk running out of matter and the Sun's strong winds blowing away the remaining gas and dust, leaving behind the major planets of the Solar System[[note]]Jupiter needed just three million years to form, Saturn likely a similar amount of time, and Uranus and Neptune longer. Had this happened later, Saturn would have been a more massive planet. Same especially for Uranus and Neptune, that were unable to grow beyond much more than their original cores. Oh, the largest moons of the outer planets are thought to have been formed in disks surrounding the giant planets, imitating the way planets had formed around the Sun[[/note]]

It was by then when the real planetary dance began. While those protoplanets of the inner Solar System were gravitationally interacting until they began to smash among themselves[[note]]At slower pace than what happened in the outer Solar System. Our Moon was formed in one of said collisions, between the proto-Earth and another Mars-sized body, Pluto's Charon could have been formed in a similar way, and similar collisions are expected to have been suffered by the other terrestrial planets. And instead of Mercury, Venus, Earth, and Mars at first could have formed large terrestrial bodies similar to those "super-Earths" found in tightly orbits around other stars (keep reading on)[[/note]], both gravitational interactions between the large planets and the many remaining planet-building blocks caused them to migrate from their original orbits, closer to the Sun than now. While Saturn, Neptune, and Uranus moved outwards[[note]]Yes, Neptune and Uranus: in said migration the two exchanged positions taking their current order[[/note]] Jupiter moved ''inwards'', messing so much with the protoplanets existing in what is now the asteroid belt that, where a large planet could have been formed, remained only what would amount comparatively speaking to detritus, either expelling it to the cold outer reaches or the Solar System, forming the Kupiter belt and the Oort Cloud or even ejecting outside it[[note]]It was not only Jupiter's fault. The other major planets had something to say too[[/note]], and would have kept approaching until it reached a very close orbit around the Sun had not gravitational interactions with Saturn caused it to move outwards to its present position[[note]]Different computer models suggest also Jupiter not only could have messed up with those hypothetical inner Super-Earths, causing them to crash among themselves or with the Sun with the current terrestrial planets forming from the [[ShatteredWorld remaining debris of those collisions]], but also that a fifth lage planet would have been ejected by Jupiter and/or another sent to the cold, outer regions of the Solar System. On a more positive note, Jupiter could have sent inward water-rich planetesimals, that would have been quite handy for the water content of the future Earth. As ScienceMarchesOn, expect some if not all of the ideas about planetary migration described there being changed in the future[[/note]]. Uranus and Neptune would also have played havoc with the remaining protoplanets of the Solar System's outer regions where they orbited scattering it even further out.

[[TakingYouWithMe The revenge of those protoplanets and other debris]] came four billion years ago in the form of a large number of them ending up in the inner Solar System, where they [[ColonyDrop pummeled to death]] the more or less formed terrestrial planets, scarring them with countless craters and causing quite a lot of damage to them[[note]]In the case of Earth, the heaviest impacts would have been enough to vaporize the oceans and even melt the crust in [[TabletopGame/Warhammer40000 Exterminatus]] fashion, wrapping the planet in an atmosphere of molten rock and water vapor for some time. It's not know if life had formed by then but if had it existed it would have been destroyed in the most violent collisions. Perhaps life formed several times, just to being destroyed again when a large impactor came crashing again, or it survived sheltered deep into Earth's crust or in the very deepest oceans. On a more positive note, it's thought those impacts brought still more water to Earth[[/note]]. This hellish rain may have lasted a few hundred million years, and was the last event of significance in the Solar System[[note]]On a more domestic scale, the remaining asteroids [[AsteroidsMonster pummeled among themselves]] in the belt further reducing the population of large bodies and producing many smaller ones, and giant planets would have captured some of those floating rocks as moons (one of them ''very'' large -ask Neptune's Triton-). Venus, that could have been an Earth-like planet became the [[DeathWorld hellish world]] that is now because of its closeness to the Sun, and Mars being too small perhaps thanks to Jupiter's journey, lost its protecting magnetic field and with it most of its atmosphere and the liquid water it's now known to have had in those epochs[[/note]]. From there until now, little has happened in the Solar System in a global scale besides the occasional impact here and there of a stray asteroid or comet, the star passing across the Oort cloud[[note]]Ask [[https://en.wikipedia.org/wiki/Gliese_710 Gliese 710]][[/note]] sending a shower of comets to the inner Solar System, and a Sun that as it ages becomes more luminous[[note]]As it fuses the hydrogen on its core, the latter contracts increasing its temperature causing an increase of the fusion rate and thus of the released energy and so on. As there's no convection in the inner regions of the Sun, just the outermost ones, our star cannot use all of its nuclear fuel.[[/note]]

As for the future, things will not change very much for the Solar System ''as a whole'' during the next five billion years[[note]]Some calculations simulations give a very small probability within that timeframe of either Mercury going haywire and being ejected of the Solar Sytem if it does not crash before into either Venus or Earth, or Mars colliding with Earth. Sleep well, it will ''not'' happen tomorrow. [[ParanoiaFuel We think]][[/note]]. Sure, the orbits of some moons such as Mars' Phobos or Neptune's Triton will decay and the latter will produce both a ''hell'' of a meteor shower and a splendid ring system around its planet, there will continue being the occasional asteroid/impact here and there, the occasional star passing too close and shaking the Oort Cloud sending comets to the inner Solar System, [[BreadEggsMilkSquick and the Earth becoming unhabitable]] because of a Sun that is brightening with time as described above but if we could see the Solar System by then it is expected we'd see something very similar to the current one[[note]]OK, the Andromeda Galaxy and the Milky Way are expected to [[FusionDance merge]] around those ages and the Sun will end up on the outskirts of the newly-formed galaxy, if not thrown out to intergalactic space (it will come back much later, though), but unless we've ''very'' bad luck the collision will not affect us[[/note]].
Five billion years was not chosen at random for the fate of our Solar System is tightly tied to the one of its most massive body: the Sun. By that epoch it will have run out of hydrogen at its center and things will become interesting, so let's fast forward to the year [[TimeAbyss 7,590,000,000 AD]][[note]]After core hydrogen exhaustion, the Sun will take its time to become a red giant -one and a half billion years still as something not very different of our current daystar -but more luminous- followed by seven hundred million years as a cooler and larger, but not more luminous subgiant star, and finally roughly six hundred million years to go full red giant. Stellar evolution takes usually its time -and remember that these are theoretical calculations, so while the basic picture will be more or less the same given numbers may somewhat change as ScienceMarchesOn-[[/note]]. In that year our familiar Sun will be in [[OneWingedAngel full red giant-mode]]: a bloated and distorted star with a surface temperature having dropped to half of what it has in our epoch, thousands of times more luminous and more than two hundred times larger than our daystar[[note]]Why if there's no more hydrogen in the core?. Hydrogen is intensely fusing instead around the small, hydrogen-exhausted, dense core of inert helium, that as it contracted caused first the hydrogen surrounding it to start fusing, and later as temperatures increased because of said contraction to fuse more and more intensely. At least, since the process will take so much time it has been calculated that temperatures will be Earth-like (the so-called "habitable zone") for some hundred million years in places as Mars or further out (Jupiter). Perhaps life will manage to appear there, even if it had little time to evolve.[[/note]], and so big that has lost more than a quarter of its mass carried away by strong solar winds, something that has caused the planet's orbits to wide, but not enough to avoid searing hot temperatures or worse[[note]]For the details: Mercury and Venus are history, having been engulfed millions of years before by the expanding Sun but not before having been roasted to Hell and back -and Venus having lost its atmosphere (poor Venus, she cannot catch a break)-. Earth, with no atmosphere to speak of and [[DeathWorld with a surface temperature of more than one thousand five hundred degrees Celsius]], is a LethalLavaLand precariously clinging to its orbit under an angry Sun that fills a whole lot of its sky and is very likely doomed to suffer the same fate than the two innermost planets. Mars is another LethalLavaLand that (we think) will survive the ordeal. Of the giant planets, temperatures will vary between the searing hot ones of Jupiter (higher than those at Mercury, but at least it could manage to accrete ''some'' (it will certainly ''not'' capture enough to be significant, much less to become a star) of the matter expelled by the Sun) and the rather Earth-like ones of Neptune, with their icy moons looking like huge comets, evaporating under the intense sunlight and probably after their surfaces have melted as temperature screamed upwards and liquid water vaporized giving hellish, worse than Venus-like conditions, to the rocky surfaces below all that ice in some cases as Europa or Ganymede. The smallest bodies -asteroids and comets-, even as far as the Kuiper Belt, not only have to contend with the intense heat but also with the mess caused to their orbits by the mass loss of the dying Sun, meaning that some of them will end being ejected out of the Solar System and others will either crash with the remaining planets or into the Sun[[/note]]. It will also be the time when the Sun will suffer a dramatic transformation: the dense, inert helium core will ignite and will produce for a few seconds ''as much energy as an entire galaxy'' in what astronomers know as the "helium flash". While this looks like a supernova, that energy will actually just be used to re-expand the core and nothing of that will be seen at its surface -in fact, with the Sun's innards expanding to fuse helium stably it will release less energy and will collapse back to a much smaller and less luminous star a bit more hot than its red giant past (somewhat more than four thousand degrees Celsius), but still quite luminous (forty-fifty times more) and large (ten times larger) compared with its past long-lived incarnation requiring several thousand years to become that[[note]]Whatever remains of the inner Solar System -perhaps only Mars- will be hotter than Mercury. Farther away, Jupiter will enjoy Earth-like temperatures and even farther our things will freeze again. Meanwhile, asteroids and the like will keep their dance of death[[/note]]. Unfortunately for the Sun helium, fusing to produce carbon and oxygen, is a worse fuel than hydrogen and even if helium burning its supported by some hydrogen fusing around the core our star will run out of it in just a hundred million years and then the Sun will face a similar crisis to the one it faced when it ran out of hydrogen there. Only this time said crisis will be fatal.
As happened with hydrogen before, helium will begin to fuse around an inert, contracting, core of carbon and oxygen[[note]]In vain; the Sun is too small to reach the temperatures and densities to fuse carbon[[/note]]. Further out, hydrogen will keep fusing to helium and as the core contracts it will "squeeze" those two burning shells causing them to fuse with more force. The result is that the Sun will become again -in just twenty million years compared to the considerably longer time (more than two billion years, see above) it needed to expand for the first time- a huge and luminous red giant suffering even stronger mass loss but, as helium burning under those extreme conditions is ''highly'' sensitive to the temperature[[note]]It scales as the temperature ''to the fortieth power''. Guess how nasty would be even small variations[[/note]], [[ClippedWingAngel an unstable one]]. Each hundred thousand years, the Sun will convulse suffering a pulse caused by a runaway helium shell burning ignition that will increase its luminosity as well as it radius just to contract when it stops and having things starting again. Those violent pulses will increase even more the already heavy mass loss as mentioned before, and by the fourth one all that will remain of the Sun will be the ''extremely'' hot -one hundred thousand degrees Celsius- and dense, as it has contracted to the size of the Earth, carbon-oxygen core half as massive as the Sun is now: a white dwarf. If the Sun is luminous enough, its ultraviolet radiation will cause the matter that ejected before to fluoresce as a beautiful [[https://en.wikipedia.org/wiki/Planetary_nebula planetary nebula]], that will however be short-lived as a few thousand years later both the gases will be rarefied and far away enough and the white dwarf's ultraviolet radiation will fade away as it begins to cool to stop shining. All that will remain to the dead white dwarf Sun is to keep cooling over [[TimeAbyss many billions of years]] until it will fade into oblivion as a black dwarf -or, if you prefer it, as a big and dense diamond as all those carbon will crystalize during said cooling-[[note]]No, we have not forgotten the planets and all that other stuff. Things will be as during the previous red giant stage, but this time ''harder'', as the Sun's convulsions will cause severe variations of temperature on them and will be pummeled by the matter expelled in the pulses. The worst, however, will come because of that severe mass drain with the Solar System becoming an even more of a mess with many small bodies, and perhaps even planets, having their orbits more or less dislocated with all that means -collisions either among them or the Sun, things being flung out, etc-. Said mess is expected to continue into the planetary nebula and white dwarf stages (it's conceivable its UV flux during the planetary nebula phase will be more or less nasty for the orbiting bodies), and whatever survives the ordeal -odds are that Jupiter at the very least- will see the black, incredibly cold, veil of an endless night being put over it. The end... or is it?. [[TimeAbyss Time will keep ticking on]], and the very occasional star passing too close will strip the dead Sun of more or less of its remaining retinue of orbiting bodies. It has been estimated that in a ''quadrillion'' (ten to the fifteenth) years, it will have lost all of them.[[/note]]