Editing 3063: Planet Definitions

{{comic
| number    = 3063
| date      = March 14, 2025
| title     = Planet Definitions
| image     = planet_definitions_2x.png
| imagesize = 653x1435px
| noexpand  = true
| titletext = 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.
}}

==Explanation==
{{incomplete|The explanation is too short.}}

This comic addresses the {{w|IAU definition of planet|controversy of whether of Pluto is a planet}} and explores many definitions, most of them humorous/nonsensical, of what a planet could be.

;Traditionalist: <u>{{w|Pluto}} is a planet</u> (9 planets)
:In modern times, there was {{w|IAU definition of planet#Background|no formal definition of a "planet"}} prior to 2006.  However, it was generally accepted as a colloquialism that there were nine planets around the {{w|Sun}}, Pluto included (starting with Pluto's discovery in 1930 ([[988|Tradition]] is whatever Baby Boomers grew up with). As more sophisticated methods of mapping the {{w|Solar System}}  were developed and {{w|Eris (dwarf planet)|Eris}} was discovered to be even more massive than Pluto, 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, disqualifying Pluto (and Eris) which is now considered a "dwarf planet." This has been subject to push back from countless people, including [https://arxiv.org/abs/2110.15285 some planetary scientists], but in numbers mostly nostalgic laypeople dissatisfied with Pluto being "demoted" or otherwise relegated.

;Modern: <u>Pluto is not a planet</u> (8 planets)
:When the IAU redefined what a planet is in 2006, Pluto no longer qualifies as a planet. (since it wasn't able to clear its neighborhood around its orbit) Using the modern definition of a planet, only eight celestial objects qualified.

;Expansive: <u>Dwarf planets are planets</u> (17+ planets)
:It is likely that since the term "dwarf planet" contained "planet" in its name, Randall considered those as also planets under this category. 
:It is also likely that the number of planets includes the ones that are considered planets and the ones that are considered to have compacted into fully solid bodies, {{w|Dwarf planet#Most likely dwarf planets| as defined by Grundy ''et al.'',}} those being {{w|Ceres (dwarf planet)|Ceres}}, Pluto, Eris, {{w|Makemake}}, {{w|Haumea}}, {{w|Gonggong (dwarf planet)|Gonggong}}, {{w|Quaoar}}, {{w|Orcus (dwarf planet|Orcus}} and {{w|Sedna (dwarf planet)|Sedna}}. 

;Ultratraditionalist: <u>Only the classical planets are planets</u> (5 planets)
:The {{w|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. There are seven classical planets, but if one were to only consider the ones that fall under the IAU's definition of a planet (this being ''less'' traditional), then there would only be five. (The Sun and the {{w|Moon}} would be disqualified)

;Condescending: <u>Only giant planets are planets; the rest are big {{w|asteroid}}s</u> (4 planets)
:This definition may refer to the {{w|giant planets}}, planets much larger than the {{w|Earth}}. Only the four outer planets fall under this definition.
;Simplistic: <u>Anything gravitationally round is a planet</u> (37+ planets)
:Using the Wikipedia {{w|list of gravitationally rounded objects of the Solar System}}, there are 37 objects listed. That includes the Sun, 8 planets, 9 dwarf planets and 19 {{w|Natural satellite|moon}}s.

;Grounded: <u>Only objects a spaceship has landed on are planets</u> (10 planets)
:This list includes objects in the Solar System that a spacecraft has {{w|List of landings on extraterrestrial bodies| performed a soft landing on}}.  The list includes {{w|Venus}}, Earth, {{w|Mars}}, the Moon, {{w|Titan (moon)|Titan}}, {{w|433 Eros|Eros}}, {{w|25143 Itokawa|Itokawa}}, {{w|162173 Ryugu|Ryugu}} and {{w|101955 Bennu|Bennu}}. Notably, {{w|comet}} landings are not included in the list.

;Regolithic: <u>Anything covered in dirt and ice and stuff is a planet</u> (infinite)
:This list excludes the {{w|Gas Giant}}s and the {{w|Ice Giant}}s. The list would likely include dwarf planets, asteroids, moons and comets. This is effectively the opposite of the "condescending" definition: every object in the solar system is included in one definition or the other (except for the Sun).

;Lunar: <u>You can't be a planet if you don't have a moon</u> (12+ objects)
:Only some objects in the solar system have known and acknowledged moons orbiting them. The value given may be {{w|List of natural satellites| the number of planets and dwarf planets}} that have moons, when excluding  {{w|Haumea}} for not reaching {{w|hydrostatic equilibrium}} despite having moons.  The Sun is excluded because its satellites are not moons, because ... oh, look, a Squirrel!

;Solipsistic: <u>Earth is the only planet</u> (1 planet)
:{{w|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.

;Judgemental: <u>Only the prettiest ones are planets</u> (6 planets)
:This list is likely formulated from Randall's own perception of the prettiest planets in the Solar System. Strangely, seven objects are highlighted:
* Earth
* Jupiter
* One of Jupiter's moons (unclear)
* Saturn
* One of Saturn's moons (unclear, possibly Titan)
* Neptune's moon (probably Triton)
* Pluto

;Empiricist: <u>Only worlds that I, author of this table, have personally seen are planets</u> (12 planets)
:This list may refer to the celestial objects in the Solar System that have been made visible at night, probably using with an optical telescope (a hobbyist one, perhaps Randall's, or from time borrowed on a major institutional installation). Jupiter's {{w|Galilean moons|four largest moons}} are technically visible but hard to distinguish due to Jupiter's brightness, while Neptune is too faint to see with a naked eye. Apparently Randall has also seen Uranus. This is fairly rare, since it usually requires a telescope pointed in just the right direction. Technically [https://www.skyatnightmagazine.com/advice/skills/how-see-uranus-in-night-sky Uranus ''is'' visible to the naked eye] under the very best viewing conditions, but these conditions are rare and it again requires knowing exactly where to look.

;Marine biologist: <u>Only objects with oceans are planets</u> (6+ planets)
:This list includes Earth, {{w|Europa (moon)|Europa}}, {{w|Ganymede (moon)|Ganymede}}, {{w|Callisto (moon)|Callisto}} and {{w|Enceladus}}.

;Maritime: <u>Only objects with ''surface'' oceans are planets</u> (2 planets)
:In the comic Earth and a Saturnian moon, likely 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. The highlighted moon of Saturn is most likely Titan due to its liquid seas of methane and nitrogen.

;Universalist: <u>They're all planets</u> (infinite)
:This list claims that all objects are planets.

;Existantialist: <u>What if {{w|outer space|space}} ''itself'' is a planet???</u> (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.

;Spiteful: <u>''Only'' Pluto is a planet</u> (1 planet)
: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.

;(title text) {{w|Star}}: <u>Earth is a star</u> (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 makes Earth fall into the category of a star due to the human-induced ability for Earth to fuse hydrogen into helium using nuclear fusion.

==Transcript==
{{incomplete transcript|Do NOT delete this tag too soon.}}
:[A table with 3 columns, the headers labelled "Definition", "# of planets", and "Solar system" and 17 rows.]
:[In each row, the first column has a single word, in bold, and a descriptive sentence, the second column has a digit or other 'value', the third column is a drawing of the Solar system, featuring various bodies and a selection of moons: The Sun, Mercury, Venuse, Earth + The Moon, Mars + two moons (Phobos and Deimos), a small selection of Asteroid Belt bodies (Ceres and other smaller examples), Jupitor + four moons (likely Io, Europa, Ganymede, and Callisto), a ringed Saturn + usually one moon (probably Titan) or two (Enceladus?), Uranus + four or five moons (likely to be Miranda, Ariel, Umbriel, Titania, and Oberon, but one of these over the face of Uranus only in some versions of the image), Neptune + one moon (probably Triton), Pluto + one moon (Charon), four more plutoid/Kuiper Belt objeccts (probably Haumea, Makemake, Gonggong and Eris, in distance order), the first two of them with distinct moons indicated (entirely dependent upon which main objects they are).]
:[Each row's illustrated solar system has indivudal combinations of green highlights applied to the otherwise repeated diagram.]
:[Row 1: Definition:] Traditionalist: Pluto is a planet [Number:] 9 [Highlit: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune and Pluto]
:[Row 2: Definition:] Modern: Pluto is not a planet [Number:] 8 [Highlit: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune]
:[Row 3: Definition:] Expansive: Dwarf planets are planets [Number:] 17+ [Highlit: 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 [Highlit: Mercury, Venus, Mars, Jupiter, Saturn]
:[Row 5: Definition:] Condescending: Only giant planets are planets; the rest are big asteroids. [Number:] 4 [Highlit: Jupiter, Saturn, Uranus, Neptune]
:[Row 6: Definition:] Simplistic: Anything gravitationally round is a planet [Number:] 37+ [Highlit: The Sun, Mercury, Venus, Earth, The Moon, Mars, Ceres (without other asteroids), Jupiter + moons, Saturn and Titan, Uranus and its moons, Neptune and its moon, Pluto and the four further dwarf planets]
:[Row 7: Definition:] Grounded: Only objects a spaceship has landed on are planets [Number:] 10 [Highlit: Venus, Earth, The Moon, Mars, five (non-Ceriese) asteroids and Titan]
:[Row 8: Definition:] Regolithic: Anything covered in dirt and ice and stuff is a planet [Number:] [infinity symbol] [Highlit: Mercury, Venus, Earth, The Moon, Mars, Ceres and across all other asteroids from the Asteroid Belt, the moons of Jupiter, the moon(!) of Saturn, the moons of Uranus, the moon of Neptune, Pluto and Charon, all remaining dwarf planets and their moons]
:[Row 9: Definition:] Lunar: You can't be a planet if you don't have a moon [Number:] 12+ [Highlit: Earth, Mars, Jupiter, Saturn, Uranus, Neptune, Pluto and three(!) of the other dwarf planets in the Kuiper belt]
:[Row 10: Definition:] Solipsitic: Earth is the only planet [Number:] 1 [Highlit: The Earth]
:[Row 11: Definition:] Judgemental: Only the prettiest ones are planets [Number:] 6 [Highlit: The Earth, Jupiter and 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 [Highlit: Mercury, Venus, The Earth, The Moon, Mars Jupiter and its four moons, Saturn and Uranus]
:[Row 13: Definition:] Marine biologist: Only objects with oceans are planets [Number:] 6+ [Highlit: 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 [Highlit: The Earth and Titan]
:[Row 15: Definition:] Universalist: They're all planets [Number:] [infinity symbol] [Highlit: All drawn objects, including The Sun and all moons]
:[Row 16: Definition:] Existantialist: What if space [next word in italics] itself is a planet??? [Word, in italics:] Duude [Highlit: The whole third column cell]
:[Row 17: Definition:] Spiteful: [next word in italics] Only Pluto is a planet [Number:] 1 [Highlit: Pluto]

==Trivia==
*The 'Judgemental' definition has 7 colored objects instead of the labelled 6.
*[https://www.explainxkcd.com/wiki/images/archive/6/66/20250314195557%21planet_definitions_2x.png The initially released version of the comic] had two errors that were later fixed:
**The 'Traditionalist' definition had Neptune's satellite {{w|Triton (moon)|Triton}} colored instead of Pluto.
**The 'Modern' definition had Pluto colored as a 9th planet. It appears that the images for 'Traditionalist' and 'Modern' were swapped.
{{comic discussion}}

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