Editing 3103: Exoplanet System

{{comic
| number    = 3103
| date      = June 16, 2025
| title     = Exoplanet System
| image     = exoplanet_system_2x.png
| imagesize = 623x447px
| noexpand  = true
| titletext = Sure, this exoplanet we discovered may seem hostile to life, but our calculations suggest it's actually in the accretion disc's habitable zone.
}}

==Explanation==
{{incomplete|Explanations for the planets are incomplete and some categories are missing. [[explain xkcd:Editor FAQ#table|Do NOT create a table]], unless it is impossible to convey that information without it.}}
{{w|Exoplanet}}s are planets outside the Sun's {{w|Solar System}}. Astronomers are constantly on the lookout for planets that might be habitable, particularly those with {{w|Earth-like_planet|Earth-like}} conditions. This gets prime attention, both because it suggests the potential for finding extraterrestrial life, and because such planets might potentially be examined as candidates for future {{w|space colonization}}. Unfortunately for many hopefuls, there are a number of specific conditions required for Earth life to survive, and there are many possible ways for space to be inhospitable to life. As a result, most exoplanets that have been discovered have conditions that make it nearly impossible for humans to survive, and difficult for any life form as we know it to exist. [[Randall]] draws a hypothetical star system containing many exoplanets that describe (in an exaggerated fashion) the many frustrations astronomers face when analyzing planets and getting their hopes up, only to discover the planets they found are, sadly, nothing like Earth.

There are a total of 19 planets in the comic. Here are the explanations for each planet, in order of how far they are from the star:

; <!-- 50px from the star-->  Giant planet orbiting so close that it's actually rolling on the star's surface
: {{w|Giant planet}}s are often gravitationally pulled close to their star. Here, the planet is literally touching the star, which, given both bodies' gaseous makeup, should cause them to merge.

; <!-- 80pxfrom the star-->  Hot Jupiter
: A {{w|Hot Jupiter}} is typical terminology used in analyzing exoplanets, generally depicting a {{w|gas giant}} (of a size similar to our {{w|Jupiter}} or {{w|Saturn}}) which orbits in a much closer/hotter orbit than our own. Hot Jupiters are easier to detect than many other types of exoplanets, due to their gravitational effect on their stars.

; <!--115px from the star-->  Planet that may actually be in the habitable zone, according to a very optimistic modeling paper by some desperate postdocs
: The {{w|habitable zone}} of a star is the range at which water is liquid. Notably, planets in the habitable zone are seen as options for colonization by humanity, which would mean greater funding for research. As such, researchers will go to great lengths to determine as many habitable planets as they can.

; <!--175px-->  There's a pulsar here but it's probably fine
: A {{w|pulsar}} is a {{w|neutron star}} which emits beams of radiation while spinning very fast. The intensity of this radiation makes it extremely difficult for any form of life to exist in the system. This is in addition to the {{w|gravitational instability}}, and excess heat that the pulsar would produce. This lends a substantial level of irony to the "probably fine" comment. Also, it means that this system is technically a {{w|binary star}}.

; <!--250px-->  A waterworld paradise with beautiful oceans and warm&mdash; wait, no, we just got new measurements, it's a hellish steam oven
: In any scientific field, new information may turn previously established knowledge on its head. Exoplanet research is no different, and a planet that at first seems to be habitable might turn out to be an incredibly deadly {{w|steam world}}. An example of this can be found in our own solar system with {{w|Venus}}, which was speculated to be habitable when its clouds were first discovered long before those clouds were found to be made of steaming hot {{w|sulfuric acid}}.

; <!--280px-->  Planet that could be habitable, if there's a form of life that hates water but loves acid and being on fire 
: Scientists remain open to the possibility that life might form from different conditions than those found on Earth. That said, the speculation that life on this planet must "love acid and being on fire" is more than a little sarcastic. Possibly to a reference to the ''[[what if? (blog)|what if?]]'' article ''{{what if|30|Interplanetary Cessna}}'', in which Randall points out that the atmosphere on Venus is pretty survivable at 55km, except for the sulfuric acid, and way too hot at the surface.

; <!--300px-->  Mini Neptune
: "Jupiter" and "Neptune" are rough size/mass categories for gas giants with a mass similar to Jupiter versus {{w|Neptune}}/{{w|Uranus}}.  A {{w|mini-Neptune}} would be smaller than Neptune, possibly small enough not to be a gas giant at all.

; <!--345px-->  Lukewarm Jupiter
: A humorous extrapolation of Hot Jupiters, assuming that there are other named types of Jupiters.

; <!--375px-->  Planet whose atmosphere is confirmed to contain atoms
: With interstellar distances, it is inevitable that some planets will be hard to get a read on. Here, the astronomers can only confirm the planet has an atmosphere, not what it is made of or how thick it is. Possibly in reference to headlines about exoplanets whose atmospheres contain molecules that may indicate biological life, but extrapolated to comedic levels of vagueness.

; <!--400px-->  Earthlike data artifact
: An {{w|Artifact (error)|artifact}} in this context is any error where it looks like something exists when it actually doesn't. This is usually caused by faults in the equipment. In this case the astronomers thought they detected an Earth-like planet, only to discover it was a data artifact. Either that, or it has turned out that {{w|Simulation_hypothesis|Earth itself is a data artifact}}, which would raise {{w|Epistemology|epistemological}} questions about the whole endeavour of studying the universe.

; <!--455px-->  Cold Jupiter
: Implicitly the opposite of a "Hot Jupiter" described above. Used here as another extension of the "Hot Jupiters" running gag, "Cold Jupiters" is occasionally used in real astronomy but is fairly informal. 

; <!--460px-->  Potentially habitable void
: It seems that the ideal orbital distance for habitable planetary conditions does not actually contain any planets. This would make it much harder to actually inhabit (the notional inhabitants would have to build a world to live on, and would have nowhere to easily locate themselves while the building was in progress), to the implied frustration of the astronomers.

; <!--485px-->  Hot {{w|Mars}}
: Continuing the joke on Hot Jupiter. This assumes that if there's hot Jupiters, there must be a "hot" variant of every planet.

; <!--510px-->  Faint dust cloud that will cause several papers to be retracted
: This could refer to either {{w|Fomalhaut b}}, a former proposed exoplanet that turned out to be a dust cloud, or {{w|Tabby's Star}}, a star with odd irregular dimming pattern likely due to a dust cloud which was briefly thought by some to be an alien megastructure.{{acn}}

; <!--515px-->  Either a gas giant or a fist-sized rock, depending upon which calibration method you use
: Even if a "fist-sized rock" were detectable around a distant star (it would be difficult to spot {{w|Russell's teapot|something of this size}} around ''our own'' star), this represents a considerable range of uncertainty between tens of thousands of kilometres and a few centimetres, being perhaps five orders of magnitude. This is not particularly precise, even for a [[2205: Types of Approximation|cosmologist]].

; <!--560px-->  Mini Pluto
: {{w|Pluto}} is already significantly smaller than most planets, thus its designation as a "{{w|dwarf planet}}". A "mini Pluto" suggests an exoplanet that shares most of Pluto's features, but is somehow ''even smaller''.

; <!--620px-->  Wet Saturn
: May be a reference to the 'fact' that "Saturn would float in water" {{w|Saturn#Physical characteristics|due to its density}}. The difficulties of finding a practical way to test this out, notwithstanding, perhaps someone managed it with this planet.

; <!--745px-->  Planet whose surface may host conditions suitable for rocks
: As with planet number 9, this planet is too difficult to get a read on, and the measurements are still so vague it's so far unknown if this planet is a rocky planet or a gas/{{w|ice giant}}.  This is also a play on the holy grail of exo-planet research -- Finding a planet whose surface hosts conditions suitable for ''life''.

; <!--840px-->  Somehow this whole system is smaller than the orbit of Mercury?!
: No planet, or anything other than an orbital path, shown. But apparently an indicator that all the rest of the given orbits (for Jupiter-likes, Mars-likes, dust clouds, etc, and even semi-inconvenient pulsars) exist within a solar system that is ''extremely'' compact, fitting into a volume of space the size of that between our Sun and the orbit of its nearest planet, {{w|Mercury}}.

: This is likely a reference to the fact that many exoplanets located so far have been in even tighter orbits around their star than Mercury is with Sol. It is worth noting however that this is likely to be observation bias as large and tightly orbiting planets have a significantly larger (and hence easier to identify) effect on the rotation of their parent star. There are likely many small and further orbiting exoplanets that we are simply unable to observe effectively at this time.

; Title text
: The title text mentions a planet within an {{w|accretion disk}}, which means that the planet is passing through material inspiralling into some significantly more massive object and is likely inspiralling itself from resistive effects of passing through said material. Nevertheless, the researcher speaking assures that the planet is in the disk's habitable zone, implying it is a worthwhile option for colonization. This is despite the observed location being likely temporary as the planet's orbit inspirals closer to the central object, to say nothing of the likely constant bombardment of debris and potential radiation depending on how massive the central object is and how dense the accretion disk is.

==Transcript==
{{incomplete transcript|Don't remove this notice too soon.}}

{{comic discussion}}<noinclude>
[[Category:Astronomy]]
[[Category:Exoplanets]]