3063: Planet Definitions

Planet Definitions

|< < Prev #3063 (March 14, 2025) Next > >|

Title text: Under the 'has cleared its orbital neighborhood' and 'fuses hydrogen into helium' definitions, thanks to human activities Earth technically no longer qualifies as a planet but DOES count as a star.

|< < Prev Random Explanation Next > >|

Explanation

This explanation is incomplete: The first paragraph is too complex and doesn't directly address the comic. If you can fix this issue, edit the page!

This comic addresses the controversy of whether of Pluto is a planet and explores many definitions, most of them humorous and nonsensical, of what a planet could be. The 2006 redefinition of Pluto as a dwarf planet is a common theme on xkcd, occurring also in 473: Still Raw, 482: Height, 1020: Orion Nebula, 1093: Forget, 1458: Small Moon, 1551: Pluto and 1555: Exoplanet Names 2.

Definition		# of planets	Explanation
Traditionalist	Pluto is a planet	9	In modern times, there was no formal definition of a "planet" prior to 2006. However, it was generally accepted as a colloquialism that there were nine planets around the Sun, Pluto included. This view started primarily with Pluto's discovery in 1930, based upon that time's scientific consensus that there ought to be another planet to account for peculiarities in the the orbits of the other outer planets. This ties back to 988: Tradition which discusses how events and beliefs that were popular in the 1940s and 1950s are considered "traditional" in the United States. As more sophisticated methods of mapping the Solar System were developed, and Eris was discovered and found to be even more massive than Pluto (which may not have been as significant as the theories that led to its discovery suggested), it became clear to astronomers that a more standardized definition was needed. In 2006 the International Astronomical Union (IAU) published their formal redefinition of a "planet" to require a planet to be gravitationally dominant within its orbit, clearing other objects that aren't moons. This disqualified Pluto and Eris, which are now considered "dwarf planets". This has been subject to pushback from nostalgic laypeople dissatisfied with Pluto being "demoted" or otherwise relegated, when schoolchildren and adults alike have 'known' that there are nine planets for the most part of the last century. Ironically, some of the latest study of the outer Solar System includes the possibility of yet another Planet Nine, but only time will tell if such an object exists and whether it would cross the IAU's current threshold or even require the threshold itself to be reassessed once more.
Modern	Pluto is not a planet	8	When the IAU redefined what a planet is in 2006, Pluto no longer qualified as a planet since it wasn't able to clear its neighborhood around its orbit. Using the modern, and recently official, definition of a planet, only eight celestial objects qualified: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune.
Expansive	Dwarf planets are planets	17+	This category also includes nine other bodies that aren't dominant within their orbits, including the ones that are considered to have compacted into fully solid bodies as defined by Grundy et al.: Ceres, Pluto, Eris, Makemake, Haumea, Gonggong, Quaoar, Orcus and Sedna. The basis for this viewpoint is the possible alternative re-evaluation that the IAU could have adopted, in that all newly discovered things like Pluto (being considered a planet at the time) should therefore be considered a planet. Indeed, Ceres had been observed some time before Pluto and had been called a planet (or a "minor planet") within both scientific and public realms.
Ultratraditionalist	Only the classical planets are planets	5	The classical planets are objects found and considered by the Greek astronomers in classical antiquity to be considered planets. Their definition of "planet" considered visible objects that move across the sky relative to the fixed stars, the original word itself being translated as "wanderer". There are seven classical planets, but this included the Sun and Moon. If one considers only the ones that also fall under either the IAU's definition of a planet (and so less traditional) or the convention before that, then there would be only five. Being mostly true to the spirit of the historic naming convention, this would be a conservative but 'valid' version of the criterion. Notably, Earth itself is not considered a planet by these criteria as, from the perspective of anyone who might even consider such things, it is not wandering the heavens. Or even in the night skies at all, but always underfoot.
Condescending	Only giant planets are planets; the rest are big asteroids	4	This definition may refer to the giant planets, planets much larger than the Earth. Only the four outer (IAU-defined) planets fall under this definition. Relegation of anything smaller, including our own planet, is an extreme attitude. Incidentally, most of the initial exoplanets discovered were, by practical necessity in their detection, also only of the "giant planet" kind.
Simplistic	Anything gravitationally round is a planet	37+	The Wikipedia list of gravitationally rounded objects of the Solar System has thirty-seven objects. It includes the Sun, eight planets, nine dwarf planets, nineteen moons, but falls short of also highlighting all of the smallest visible objects (per Universalist, below). This definition is essentially part of the actual current definition of a planet, leaving out the main factor that disqualifies Pluto, orbital dominance.
Grounded	Only objects a spaceship has landed on are planets	10	This list includes objects in the Solar System that a spacecraft has performed a soft landing on. The list includes Venus, Earth, Mars, the Moon, Titan, the comet Churyumov-Gerasimenko plus the asteroids Eros, Itokawa, Ryugu, and Bennu. The justification for this seems to be that we must 'touch' the object before we consider it as worthy of being classified as more than a mere blob (or dot) in space. It could be argued that Jupiter and Saturn also count, due to the Galileo and Cassini spacecraft respectively, which plunged into the atmospheres of those planets.
Regolithic	Anything covered in dirt and ice and stuff is a planet	Infinite	This list excludes the gas giants and ice giants. The list would likely include all other planets, plus all dwarf planets, asteroids, moons, comets and trillions of other objects in the Oort cloud that are larger than a few particles in size. (Not strictly infinite, but uncountably many for all practical reasons.) This is effectively the opposite of the "condescending" definition: every object in the Solar System except the Sun is included in one definition or the other. This is also an extension on the "Grounded" classification. In this case we could meaningfully touch the object, with predominantly atmospheric bodies being not considered so.
Lunar	You can't be a planet if you don't have a moon	12+	Only some objects in the solar system have known moons orbiting them. The value given may be the number of planets and dwarf planets that have moons, excluding Haumea for not being spherical despite having moons. Adopting this definition would suggest that a planetary body is not worthy of the name if it doesn't demonstrably dominate its orbit by having at least one satellite of its own. If this statement were "You can't be a planet if you don't have a Moon", only the Earth would qualify.
Solipsistic	Earth is the only planet	1	Solipsism is the idea that only one's own mind is sure to exist. Randall extrapolated this idea to mean that only one's own planet that they are standing on is sure to exist. This relies on a more philosophical and/or semiotic assessment than any scientific one.
Judgemental	Only the prettiest ones are planets	6	This list is likely formulated from Randall's own perception of the prettiest planets in the Solar System. Seven objects are highlighted: Earth, Jupiter, one of Jupiter's moons (likely Europa, based on 1547: Solar System Questions), Saturn, one of Saturn's moons (possibly Iapetus or Phoebe), Triton and Pluto. The subjectivity of this version of the definition makes it unlikely that a consensus of this form could be established.
Empiricist	Only worlds that I, author of this table, have personally seen are planets	12	This list may refer to the celestial objects in the Solar System that have been visible at night for the author (or that the author has never seen the Sun), probably going so far as using an optical telescope (which could be a hobbyist one, perhaps Randall's own, or from time granted on a major institutional installation) but not any more indirect method that uses a camera/screen or historic images of any kind. Apparently Randall has seen Uranus, which technically is visible to the naked eye under the very best viewing conditions, but these conditions are rare and it requires knowing exactly where to look. Jupiter's four largest moons are technically visible to the naked eye but hard to distinguish due to Jupiter's brightness, while Neptune is considered too faint to see even if you know where to look. It appears that Randall has never used a telescope to see Neptune. As a different form of subjectivity, the value of this grouping's criteria is questionable, but not uncommon in other 'softer' sciences.
Marine biologist	Only objects with oceans are planets	6+	This list includes Earth, Europa, Ganymede, Callisto, Titan and Enceladus. These have had the presence of significant liquid identified from measurements of their magnetic/electric fields, but see the "Maritime" entry. There is a resemblance, here, to a loose understanding of what a "world" is, i.e., one that possesses various distinct 'terrains' beyond mere dry (and possibly considered featureless) rock. A marine biologist would, of course consider a marine (if not pelagic or bathyspheric) environment to be an essential element of any world.
Maritime	Only objects with surface oceans are planets	2	In the comic, only Earth and Titan are highlighted. Earth is the only body known in the solar system to have liquid water on the surface significant enough to be called an ocean. Titan's cold and dense atmosphere notably maintains surface 'seas' of methane and nitrogen, while other moons (given as additional in the prior item) seem to have their liquid water beneath either whole-surface ice caps or otherwise deep under the surface. From the narrower point of view of a sailor, for example, there is no benefit in considering water hidden away far beneath the surface, and it might as well not be there. In contrast, it's possible that a well-prepared mariner could sail the strange seas of Titan, as easily as (or easier than) an aircraft might fly through its skies.
Universalist	They're all planets	Infinite	This list claims that all objects are planets, with all drawn items (also presumably all undrawn/undrawable items) being marked as such, including the Sun. Giving up on any thought of exclusivity, this unconventional view willingly inducts all objects into consideration, with an effectively equivalent claim to an infinite count as with the Regolith definition.
Existentialist	What if space itself is a planet???	Duude	This list is different from the list above as it claims that all of space, rather than only the objects existing in space, are planets. The interjection Duude expresses one's amazement at this 'revelation' and replaces the number count— and is sometimes used to imply the speaker is high on marijuana or other mind-altering drugs. The strange stretch of imagination, as prompted by some narcotic or other, abandons all pretense at sensibly sorting everything into "planet" or "not planet", as not only is everything a planet, but so is the nothing between these titular planets. However, the more serious subject of black hole cosmology holds the view that the observable universe is the interior of a black hole.
Spiteful	Only Pluto is a planet	1	This list is a malicious play on the demotion of Pluto by demoting all other planets except Pluto instead, leaving Pluto as the only planet in the solar system. This is the taxonomic equivalent of refusing to play and taking your ball home to spite those who you think don't deserve to enjoy themselves.
Star (title text)	Earth is a star	2 stars	In May 1934, Mark Oliphant, Paul Harteck and Ernest Rutherford at the Cavendish Laboratory published an intentional deuterium fusion experiment and made the discovery of both tritium and helium-3. This is widely considered the first experimental demonstration of fusion. Randall considers that this and subsequent human-induced fusion makes Earth fall into the category of a star, and hence not a planet. Also, the IAU definition of a planet requires that the planet has cleared its "orbital neighborhood" of other objects — objects must either be captured as moons or have their orbits disrupted such that they are flung away. Under this definition, one could humorously argue that recent human activities, launching into space new non-orbiting objects like the James Webb Space Telescope, technically disqualify Earth from being a planet, as the orbital neighborhood is no longer completely clear. By changing not only the definition, but the term being defined, this drifts yet further from any consensus view on the original question and into a typical punchline absurdity.

Transcript

This transcript is incomplete: Do NOT delete this tag too soon. If you can fix this issue, edit the page!

[A table with 3 columns, and 17 rows below the the header row, labelled "Definition", "# of planets" and "Solar system".]

[In each row, the first column has a single word, in bold, then a descriptive sentence. The second column has a digit or other 'value'. The third column is a not-to-scale drawing of the Solar system, featuring the Sun, various 'planetary' bodies and an apparently selective sample of moons and asteroids, as follows: The Sun, Mercury, Venus, Earth with the Moon, Mars with its two moons (Phobos and Deimos), a small selection of some asteroid belt bodies (Ceres in the midst of other, smaller, examples), Jupiter and four of its moons (likely the Galilean moons: Io, Europa, Ganymede and Callisto), a ringed Saturn and usually one of its moons (probably Titan) or two (possibly Enceladus or Iapetus, as required), Uranus and four or five of its moons (likely to be Miranda, Ariel, Umbriel, Titania and Oberon, but one of these (shown upon the face of Uranus) only appears in some iterations of the base image), Neptune and one of its moons (probably Triton), Pluto and one of its moons (Charon, the main companion body possibly considered as fellow twin-dwarf instead), four more plutoid or Kuiper Belt objects (too little context to identify, but possibly Haumea, Makemake, Eris and Sedna, in distance order), the first two of them with distinct moons/companions indicated (the exact identities entirely dependent upon which main objects they are partnering).]

[Each row's illustrated solar system has individual combinations of green highlights applied to the otherwise repeated diagram.]

[Row 1: Definition:] Traditionalist: Pluto is a planet [Number:] 9 [Highlighted: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune and Pluto]

[Row 2: Definition:] Modern: Pluto is not a planet [Number:] 8 [Highlighted: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune]

[Row 3: Definition:] Expansive: Dwarf planets are planets [Number:] 17+ [Highlighted: Mercury, Venus, Earth, Mars, Ceres (in Asteroid Belt), Jupiter, Saturn, Uranus, Neptune, Pluto and the further main bodies]

[Row 4: Definition:] Ultratraditionalist: Only the classical planets are planets [Number:] 5 [Highlighted: Mercury, Venus, Mars, Jupiter, Saturn]

[Row 5: Definition:] Condescending: Only giant planets are planets; the rest are big asteroids. [Number:] 4 [Highlighted: Jupiter, Saturn, Uranus, Neptune]

[Row 6: Definition:] Simplistic: Anything gravitationally round is a planet [Number:] 37+ [Highlighted: The Sun, Mercury, Venus, Earth, The Moon, Mars, Ceres (without other asteroids), Jupiter + moons, Saturn with Titan, Uranus and its moons, Neptune with its moon, Pluto and the four further dwarf planets, your mom]

[Row 7: Definition:] Grounded: Only objects a spaceship has landed on are planets [Number:] 10 [Highlighted: Venus, Earth, The Moon, Mars, five (non-Cererian) asteroids and Titan]

[Row 8: Definition:] Regolithic: Anything covered in dirt and ice and stuff is a planet [Number:] [infinity symbol] [Highlighted: Mercury, Venus, Earth, The Moon, Mars, Ceres with all other asteroids depicted in the Asteroid Belt, the moons of Jupiter, the sole representative moon of Saturn, the moons of Uranus, the moon of Neptune, Pluto, Charon (Pluto's ’moon’/twin-dwarf companion) and all remaining dwarf planets together with their illustrated moons]

[Row 9: Definition:] Lunar: You can't be a planet if you don't have a moon [Number:] 12+ [Highlighted: Earth, Mars, Jupiter, Saturn, Uranus, Neptune, Pluto and three of the other dwarf planets in the Kuiper belt, including one with no obviously drawn moon]

[Row 10: Definition:] Solipsistic: Earth is the only planet [Number:] 1 [Highlighted: The Earth]

[Row 11: Definition:] Judgemental: Only the prettiest ones are planets [Number:] 6 [Highlighted: The Earth, Jupiter with one of its moons (not identified), Saturn, one of two Saturnian moons in this image and Pluto]

[Row 12: Definition:] Empiricist: Only worlds that I, author of this table, have personally seen are planets [Number:] 12 [Highlighted: Mercury, Venus, The Earth, The Moon, Mars, Jupiter with its four moons, Saturn and Uranus]

[Row 13: Definition:] Marine biologist: Only objects with oceans are planets [Number:] 6+ [Highlighted: The Earth, three Jovian moons, the two illustrated Saturnian moons]

[Row 14: Definition:] Maritime: Only objects with [next word in italics] surface oceans are planets [Number:] 2 [Highlighted: The Earth and Titan]

[Row 15: Definition:] Universalist: They're all planets [Number:] [infinity symbol] [Highlighted: All drawn objects, including The Sun and all other objects including all the moons/asteroids]

[Row 16: Definition:] Existentialist: What if space [next word in italics] itself is a planet??? [Word:] Duude [Highlighted: The whole third column cell]

[Row 17: Definition:] Spiteful: [next word in italics] Only Pluto is a planet [Number:] 1 [Highlighted: Pluto]

Trivia

• In the original version of the comic, there were two errors that would later be fixed. The "Traditionalist" definition highlighted Neptune's satellite Triton instead of Pluto. The images of the Solar System for the "Traditionalist" and "Modern" definitions were swapped, resulting in Pluto being incorrectly highlighted in "Modern" and omitted in "Traditionalist".

• The "Judgemental" definition has seven colored objects instead of the stated six. This mistake has not yet been fixed.

  Add comment        Create topic (use sparingly)       Refresh 

Discussion

The one currently posted has Pluto highlighted in the second box and not highlighted in the first box. Too hard to tell if it's trolling or a genuine mistake. :-D

Apparently a mistake since it's fixed now. HughNo (talk) 19:59, 14 March 2025 (UTC)

And the first one also has a moon hilighted instead I think?? 162.158.126.5 15:59, 14 March 2025 (UTC)

Was about to write the same. The coloring in the first two lines arund Pluto seem wrong (or mistankingly switched). --172.71.222.246 16:17, 14 March 2025 (UTC)

This, this is the hill I will die on. I was radicalised by this paper: Moons Are Planets: "Scientific Usefulness Versus Cultural Teleology in the Taxonomy of Planetary Science" In short; planets are what planetary scientists study. Round things with the *good stuff*: atmospheres, oceans, volcanoes (of lava or water ice) (see diagram page 53). Pluto, Titan, Ceres, Io and Europa are all in the sweet spot where you're not so small you're just a lump of rocks who happen to be stuck together into a lump, and not so large you're just a mostly undifferentiated mass of fusing hydrogen/helium plasma. And it's consistent with our pre-20th Century understanding of what a planet is, whereas the IAU definition is trying to preserve 19th Century astrology. An amazing read and a strong recommend for anyone who cares about this subject. 172.69.79.138 16:45, 14 March 2025 (UTC)

Ooh, thank you! That was fascinating and I'm head-canonizing that definition now. –P₁h₃r₁e₃d₁₃ (talk) 23:57, 17 March 2025 (UTC)

Does this sort of count as pi-related for pi day? TomtheBuilder (talk) 17:04, 14 March 2025 (UTC)

he doesn't do themed comics anymore 😔 Caliban (talk) 17:12, 14 March 2025 (UTC)

Sure he does. 2962 and 2969 weren't too long ago. Seems like it, though. 172.71.182.222 03:31, 15 March 2025 (UTC)

I don't understand either the "he doesn't do themes" bit, or the full nature of the reply, frankly. 172.68.205.122 22:52, 15 March 2025 (UTC)

I was somewhat disappointed to get to the end of the table without seeing either an astrology or Sailor Moon joke. -- Angel (talk) 18:12, 14 March 2025 (UTC)

Is it possible that Uranus is marked under "Empiricist" because of the "Randall has seen Uranus" joke? 172.70.42.178 18:38, 14 March 2025 (UTC)

The "Classical Planets" should be 7, including the Sun and the Moon.

The average distance of the orbit of the Moon around the Earth must be slightly farther away than the orbit of the Sun around the Earth, since the Moon lags behind the Sun a little more each day, but the orbits must cross or we would never have a solar eclipse :P SammyChips (talk) 19:41, 14 March 2025 (UTC)

Wouldn't the Regolithic one depend on the exact definitions of "dirt", "ice", and "covered"? It seems that an argument could be made that the giant planets also count there but have a much thicker atmosphere on the outside, and disqualifying because of the atmosphere could exclude others like Earth depending on the exact threshold used. SammyChips (talk) 19:08, 14 March 2025 (UTC)

Has Randall not seen the sun before?

I'm impressed that he has seen Uranus (unless that actually is a joke), especially if he saw it unaided (apparently it actually can be barely seen with the naked eye if the conditions are incredibly good). SammyChips (talk) 19:36, 14 March 2025 (UTC)

Could the sun be classified as a "world"? --MothWaves (talk) 19:43, 14 March 2025 (UTC)

I assumed he meant "seen directly with my eyes", so that a photograph would not count, but looking through a telescope during an astronomy night at the local University would count. And he hasn't looked *closely* at the Sun, because of the need for eye protection. JimJJewett (talk) 23:49, 14 March 2025 (UTC)

Technically, spacecraft have landed on Mercury, Jupiter, and Saturn. Just not in a survivable manner. Redacted II (talk) 19:37, 14 March 2025 (UTC)

Have we really not sent anything directly into the Sun yet? JimJJewett (talk) 23:51, 14 March 2025 (UTC)

The most "into the Sun" we've done is the Parker Solar Probe, and it hasn't attempted to 'land' there (apart from that being effectively impossible, even beyond the likes of Cassini's final fall "onto" Saturn). It's also very hard to even send things into the Sun, because the direct method would need you to send a craft from Earth backwards at the same speed as the Earth orbits forwards (or very close to that), otherwise all you can do is fall past it and loop back up again. 162.158.74.94 01:00, 15 March 2025 (UTC)

No one even knows if Jupiter and Saturn have a *land* to land on. SDSpivey (talk) 14:54, 15 March 2025 (UTC)

Sstill subject to further study, but the crushed and burnt (and probably unrecognisable) remains of the probes will be 'landed' (or floating on top of any layer that they're ultimately more buoyant than) down there, somewhere (unless they're totally ablated away, but there'll probably be some fragments of hi-tech metal frame, even if no circuit boards or metal foils survive) Should there be a form of life in existence down in the depths of the gas-giant's mass, with any curiosity to them, I imagine they'll be wondering what this new variety of 'space rain' is, that's totally unlike the usual ex-asteroidal/cometish stuff that they must occasionally get punching down through from the inaccessible upper reaches above their native environment. 162.158.74.68 19:59, 15 March 2025 (UTC)

It looks like the Pluto error in Traditionalist and Modernist images were fixed. I now see Pluto highlighted in traditionalist and Pluto unhighlighted in Modern. 172.68.7.91 19:44, 14 March 2025 (UTC)

indeed, it seems fine now, i removed my earlier comment--162.158.233.116 23:06, 14 March 2025 (UTC)

//Jean-Luc Margot wrote a serious planet definition proposal// in 2024 as a starting point for community conversations and welcomes feedback. In 2019 I wrote a small article myself on planet and moon classes simply by size. //Mondklassen "wwwahnsinn"// (in German). 162.158.159.108 19:49, 14 March 2025 (UTC)

I'm disputing that there has never been a formal definition of "planet" prior to 2006 - the ancient Greek definition of "wandering [relative to seemingly-fixed stars] points of light in the night sky" seems formal enough to me. I marked it {{actual citation needed}}. 198.41.227.73 19:52, 14 March 2025‎

I've reworded the sentence to say "in modern times" so we aren't making unfounded and likely-incorrect claims about antiquity. 198.41.227.73 21:19, 14 March 2025 (UTC)

Does anyone else strongly dislike the term natural satellite replacing moon? Under the new nomenclature, only Earth's moon is 'the Moon'. All other moons are now merely natural satellites. Phobos, Deimos, Ganymede, are no longer considered moons. My biggest problem with the new definition is that planets themselves are natural satellites of stars. 172.71.182.225 20:13, 14 March 2025 (UTC)

It seems likely that the Saturnian moon highlighted in the Maritime definition is Titan, since it has liquid seas and lakes on its surface. 172.69.6.5 21:54, 14 March 2025 (UTC)

I've noted in the Transcript that (despite apparently being identical pre-highlight drawings in all other ways, or at least very consistently reproduced), Saturn is given one moon most of the time, but two moons on occasion. Similarly, Uranus's moons (spread from upper-right to lower-left) do-or-do-not include the dot (in one case suffering a highlighting) moving across the face of the planet. From an analytical perspective, I'm wondering if Randall did indeed copypaste the 'normal' iillustration, but then have to manually add in "whoops, I forgot I need to highlight a further item thaat I haven't already drawn" into some of the established copies, touching up where necessary (and maybe where still not necessary too). ...But I'm not sure it matters what he did or did not do. It's just an observation about the result. 172.69.79.190 23:03, 14 March 2025 (UTC)

Yeah, Titan's present in all the diagrams, and a second moon of Saturn shows up when highlighting is necessary. The bonus "Marine Biologist" planet is clearly Enceladus, but the bonus "Judgemental" planet doesn't line up with it: presumably it's one of Saturn's other moons. Which one? My wild guess is Iapetus. 172.68.150.27 01:48, 15 March 2025 (UTC)

Great explanation, thank you, but was it really necessary to include a snide dig at Baby Boomers? Not a BB myself - I'm gen X, if we're using those facile labels - but surely we don't need to encourage intergenerational resentment and conflict. 172.68.174.116 03:22, 15 March 2025 (UTC)
As a historian, I strongly disagree with the snide definition of tradition. (No, not a BB.) 162.158.212.132 07:40, 15 March 2025 (UTC)

That's a direct quote from a prior comic, that whoever wrote it in the first placce ysed, so I've rewritten it to perhaps not look quite so much like some editor's own grudge/snidiness (which it may or may not be, but not without Randall giving justifiable precedent to say it). Maybe can be tweaked further, but it might be a shame to lose the inter-comic referential humour that (regardless of tone) is staple for this site. 162.158.74.109 12:25, 15 March 2025 (UTC)

I wrote it. No snideness intended. I thought the connection was topical. Unfortunately, thanks to the "Okay boomer" phenomenon, any reference to the generation comes across as condescending. The "Tradition" strip was published in 2011, and the phrase rose to popularity in 2019. It, like 36, is just one of those things that is not standing the test of time. 172.70.47.89 20:22, 15 March 2025 (UTC)

I believe we're currently missing part of the joke in the mouseover text. Not only is Earth now a star because of human fusion, it's also no longer a planet, because, due to human satellites and spacecraft, it no longer clears its orbit. 198.41.227.42 06:20, 15 March 2025 (UTC)

Isn't the usual singular of criteria criterion? According to my dictionary, a criterium is a type of cycling race.--172.71.26.100 09:46, 15 March 2025 (UTC)

Indeed. Maybe a thinko, though, rather. 172.69.79.139 11:06, 15 March 2025 (UTC)

I am curious why only one of the Galilean moons counts as pretty, and I wonder which one (either Ganymede or Callisto, given where its drawn). They are all pretty to me, I like how surprisingly distinct they look from one another. Terdragontra (talk) 13:18, 15 March 2025 (UTC)

Re title text: With the launch of the JWST, Earth has no longer cleared its orbital neighborhood, right? 172.70.176.57 14:27, 15 March 2025 (UTC)

I tend to go by an expansive definition myself, considering all dwarf planets "planets" in my eyes. But I'm not like, arguing with the IAU's definition, this is just how I prefer to think of them, because dwarf planets are really cool. 172.70.126.140 19:35, 15 March 2025 (UTC)

In the title text explanation, there's no mention of the inclusion of the phrase about Earth clearing its orbital neighborhood. I think this has something to do with all of our man-made satellites that have not been cleared from Earth's orbital neighborhood. Does anyone else think that's an important part of the title text and needs to be explained? Ianrbibtitlht (talk) 13:33, 16 March 2025 (UTC)

I think I like the "Recognizable" criteria. Something is a planet if it orbits the Sun and there exists at least one photograph of the object that a reasonably knowledgeable layperson can correctly identify. That would mean that all of the IAU defined planets are planets (except maybe Mercury), and that Pluto became a planet in 2015. 172.68.245.141 14:34, 16 March 2025 (UTC)

...there's a risk that Uranus and/or Neptune ("or both... hang on... which one's supposed to be bluer..? and is this one of those miscalibrated images or not..?") might drop out of the Recognisable grouping. And the Moon would be added, unless you arbitrarily banned near-side images, in which case it'd be demoted to "dunno" except by particularly adept selenophiles who probably even know the far-side, and limbs, like the back of their own hands. 162.158.74.94 16:55, 16 March 2025 (UTC)

A definition I thought up a while ago that I'm pretty proud of is that a planet is an object that is not a star or moon, has a stable orbit around a star, and that has a larger mass than the largest moon in its solar system. (a moon is defined as having a barycenter inside an object that directly orbits the Sun). That way, there is a clear, natural, distinction of larger bodies and smaller ones that conforms to the public thinking of a planet as large and not a moon. By my definition, the planets are Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune. (Though Mercury is famously smaller in radius than the moons Ganymede and Titan, it has more mass -- and given that mass grants greater gravity, I consider mass to be more important). My wider category of a world is for all star-orbiters that have differentiated layers, so the worlds in the Solar System would be (I think) Mercury, Venus, Earth, the Moon, Ceres, Vesta, Jupiter, Ganymede, Callisto, Europa, Io, Saturn, Titan, Uranus, Neptune, Triton, Pluto, Charon, Quaoar, Haumea, Makemake, Gonggong, Eris, and Sedna. This would be a harder category to assign than planet and a bit more fuzzy -- which plays in to the fuzzy use of world already existing -- but is still more clear cut than "gravitationally rounded" as no object is a perfect sphere and the strict definition of hydrostatic equilibrium means Mercury is not a planet. Of course, since no exomoons have been discovered as they are very hard to find, all exoplanets discovered would be planets -- which is nice and uncomplicated and natural for the human to assume that the bodies are planets. 108.162.245.145 18:11, 16 March 2025 (UTC)

Having the status of bodies be contingent on what is going on elsewhere seems even more problematic than current arguments over where artificial lines between categories should be drawn. In theory, Jupiter could capture a passing wandering planet and, under your system, instantly demote a bunch of the current planets to non-planets, even though nothing about them has actually changed.172.70.160.219 09:51, 18 March 2025 (UTC)

And, in a way, that's what happened to Pluto. Nobody was really bothered about it not having 'cleared' Neptune from its orbit (or, it appears, consider it a problem that Neptune hasn't cleared Pluto from its own, so already a partial fudge of meaning there) when it was an acceptible planet. Maybe the runt of the litter (comparing disfavourably against even some moons, including our own), but most people were happy to slide with it as one (with perhaps a bit more attention on Ceres, too, once more), even as it became clear that its own largest moon was more co-binary, and that there were a number of other (lesser) plutoids doing the same sort of thing. The 'sudden appearance' (i.e. realisation of) a larger (now dwarf-)planet changed that.

I mean, I'm not advocating for either turn of terminology (though I definitely grew up, and lived most my adult life, knowing that Pluto was a planet), but taxonomy of all kinds is tricky. Just ask Linnaeus. As more information overturns how we group things, even when the realities of the things we group don't themselves change. 172.70.162.57 11:23, 18 March 2025 (UTC)

"Modern" vs "Current". Does anyone feel frustrated when people confuse "modern", "contemporary", and "current"? "Modern" is post-1500, "contemporary" is the age someone lives in, and "current" is 'today'. Throughout 75 years of the modern era, Pluto 'was' considered a planet. Is anyone willing to shift non-canonical usage of "modern" to "current" in the article? 172.71.95.28 15:59, 15 March 2025 (UTC)

"Modern" is post-1500" -- Museum of Modern Art, 1929/1930 until today (essentially Pluto's reign); works to 1885 --PRR (talk) 00:54, 17 March 2025 (UTC)

Modernity#Scientific. It varies a bit field by field, but in science, philosophy, and history, "modernity" begins around 1500. Western History is divided into classical antiquity, middle ages, and modernity. Oh, and Copernicus, father of modern (non-classical) astronomy? He lived 1473-1543. 104.23.170.4 02:07, 20 March 2025 (UTC)

I added a bunch of Wikipedia citations. I went by the WP rule (citation needed) of linking the first non-parenthesized instance of a word/phrase. That does make for some awkward things, like lists with only some of the items linked, and the moon link in a mention under Simplistic rather than on the more relevant Lunar. –P₁h₃r₁e₃d₁₃ (talk) 22:34, 14 March 2025 (UTC)

That all went to pot a bit, anyway, when it was all transformed into a sortable table. (I'm a big fan of a handy table, in the right circumstances, but I'm not sure it was necessarily the better format in this case.) What might be best, in demanding a tabled case, is to have a table of objects (both displayed and referenced), and then explain in which comic-table rows they do (or should, or maybe) appear. 172.70.86.115 13:22, 20 March 2025 (UTC)

According to the "simplistic" definition, the rings themselves (also round) are separate planets. If the simplistic definition had merely been "spheroidal" rather than "round", they would not be. I'd love to see a version of the chart where Saturn is green, but the rings are white. 172.71.99.166 23:36, 14 March 2025 (UTC)

Shouldn't the Utratraditionalist version of the solar system have 7 planets (including the Sun and the Moon)? 172.68.245.136 15:15, 17 March 2025 (UTC)

Given that it is now considered a dwarf planet, and a lot of people, and perhaps the world itself, are unhappy, would it not be appropriate to rename it Grumpy? -- Jmbryant (talk) 12:22, 18 March 2025 (please sign your comments with ~~~~)

I wonder if this comic was tangentially inspired by the fairly recent discovery of a further 128 (suspiciously round number, that..!) moons of Saturn, making it now having well into the 200 'moons', on top of its ring-debris. And the possibility of the IAU having to weigh in and now officially decide what a moon is, especially in contrast to all the material in Saturn's rings (maybe broken up ex-moons, possibly raw material for future moon-clumps). One would suspect a version of "clear the area around the planet it orbits", and a (looser?) threshold of hydrostatic equilibreum/sphericity might be the starting point. 172.69.43.221 13:54, 18 March 2025 (UTC)

There should be a “Dayist” list of objects that have a day of the week named after them: Sun (Sunday), Moon (Monday), Mercury (Tuesday), Jupiter (Wednesday), Mars (Thursday), Venus (Friday), and Saturn (Staurday). 172.69.67.147 19:56, 18 March 2025 (UTC)

Mild correction: Tuesday is named for Mars, Mercury lends its name to Wednesday, and Jupiter Thursday. Also this would be the Ultratraditionalist definition, but Randall excluded the Sun and Moon from that for some reason. 108.162.227.64 (talk) 12:12, 7 April 2025‎ (please sign your comments with ~~~~)

Depends upon your pantheon, and your interpretations/inter-relations with the others. Wednesday is named for Wodan/Wotan/Odin/etc, the head of the Norse-like gods, so is equivalent to Jove/Jupiter of the Latinesque pantheon (even though latinesque day-naming indeed goes instead with Mercury to inspire "Mercredi"/etc). By tradition, Odin was also associated with Mercury, but it's so mixed up that it still might not be particularly germane in this case.

Tuesday is more Mars, Týr/Tiw being the son of Odin (maybe, could also be from the not-god/jottun Hymir) who has the aspect of conflict and thus is Mars the mediteranean god and directly Mars the planet.

Thusday (being Thor) does not normally have a planet associated with him. Sometimes (instead of Odin), being equated to Jove/Jupiter (probably the lightning, as from the Zeus of the Greek equivalence/basis for Roman theistic lore), but at other times more just Hercules (planetless). I dare say that those more familiar with some of his MCU appearances probably would say war/Mars, these days!

The core Anglo-Saxon (and a lot of the unsyncratic versions of the northern-European legends, before Rome started trying to say "you worship <'pagan' god>, and that's ok, because we recognise them too, as an aspect of <Roman god>, and will gladly build/improve a temple dedicated to <pagano-Roman synthesis version> as a token of you all now being Roman!") didn't really do so much "days<-+->planets linking". "Saturday" used to be "Washing day", before Saturn (as a figure from the Roman myth, technically considered the same as the Titan Cronos, who was in that case more a "season of harvests" figure than one given a day, but the mixing and matching is somewhat complicated across this original 'home' region) made his way into that position. Further cultures may well have other ideas, probably beyond the scope of this explanation, and I think even 'close' non-anglo interpretations (e.g. the Romance tradition) shouldn't be looked at beyond what is the current not-all-planets list. 172.69.195.121 14:36, 7 April 2025 (UTC)

Might be worth mentioning that Neil DeGrasse Tyson was a proponent(ish) of the "Condescending" view "He said he'd take all four rocky planets in our solar system — Earth, Mars, Mercury and Venus — and call them dwarf planets rather than admit Pluto to the planet club."- https://www.space.com/29960-stephen-colbert-pluto-neil-tyson-video.html 172.70.42.168 21:29, 18 March 2025 (UTC)

The reactionary traditionalists ought to be told that if Pluto is a planet, then so is Eris, so even then, there would not be nine planets, but 10. (No mention on whether it's in the 8th dimension) -- -- KeithTyler (talk) 22:39, 19 March 2025 (UTC) (please sign your comments with ~~~~)

Two planets: Pluto and Eris. And, as with "King Buns", Pluto is the most important! 172.70.86.115 13:22, 20 March 2025 (UTC)
        Add comment