https://www.explainxkcd.com/wiki/api.php?action=feedcontributions&feedformat=atom&user=Ban+me+I+dare+youexplain xkcd - User contributions [en]2026-05-03T18:39:04ZUser contributionsMediaWiki 1.30.0https://www.explainxkcd.com/wiki/index.php?title=3037:_Radon&diff=3620843037: Radon2025-01-14T18:43:25Z<p>Ban me I dare you: just a random change</p>
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<div>{{comic<br />
| number = 3037<br />
| date = January 13, 2025<br />
| title = Radon<br />
| image = radon_2x.png<br />
| imagesize = 740x291px<br />
| noexpand = true<br />
| titletext = A good ²³⁸Umbrella policy should cover it.<br />
}}<br />
<br />
==Explanation==<br />
{{incomplete|Created by an INCOMPLETE PASS - Please change this comment when editing this page. Do NOT delete this tag too soon.}}<br />
In this comic, [[Ponytail]] approaches [[Cueball]] about the concentration of {{w|radon}} in his basement. This refers to a common phenomenon where the levels of radon gases can build up in enclosed spaces over time; they form out of traces of {{w|uranium}} embedded in the surrounding bedrock/soils of most basements, and in the silicate minerals used in the concrete of the foundation. This uranium (over time, and in most cases via the midpoint of thorium) releases radon as a gas whilst experiencing alpha decay, although the time in which this occurs is noticeably long. Uranium-238, the isotope mentioned in the title text, has a half-life of 4.5 billion years, which is about the age of the Earth. Over the whole Earth, roughly 2.8 ppm of the planet is made of uranium<ref>https://world-nuclear.org/information-library/nuclear-fuel-cycle/mining-of-uranium/uranium-mining-overview</ref>; this is about 0.00028% of the planet, which weighs about 5.9722*10^24 kilograms<ref>https://nssdc.gsfc.nasa.gov/planetary/factsheet/earthfact.html</ref>. Even so, if uranium existed in the Earth's crust alone - about 1% of the Earth's total mass itself - this would imply that there is <!--(5.9722*10^24 * 0.00028 * 0.01 =)--> 1.672216*10^19 kilograms of uranium across the entire planet. Thus, radon gas is not ''that'' uncommon a phenomenon, and {{w|Radon mitigation|radon mitigation}} techniques are frequently employed to keep the air safe and breathable. Basements, in particular, are known to accumulate radon gas if they are kept sealed over long enough time; that is, the windows and doors are closed. Small cracks in the house's foundation may allow some radon gas to seep inside, which can be cleared if the basement is properly ventilated. Radon is denser than air, but its concentrations are higher in the basement than elsewhere in a building because of the combination of its being generated more there, and the relatively poor air circulation usual in basements. Radon mixes completely with air, and does not "settle out". Undisturbed, the concentration of radon reaches a steady state in a given area, between accumulation from being generated, and removal by air circulation and by radioactive decay.<br />
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The actual amount of uranium experienced in any given environment, according [[Randall|Randall's]] own [[Radiation|Radiation chart]], is 10 microsieverts worth of radiation, on average, over a year; the amount in one's body, in contrast, is about 390 microsievert over that same timeframe, again on average. The lowest dose linked to any serious risk is in the millisievert range, over thousands of times ''stronger'' than any of these sources. Thus the ''radiation'' from radon buildup in a normal house is not of concern, as long as it is properly managed in time. Instead it is radon's ''toxicity'' that is the problem, both from the radon itself and its "daughter" isotopes, that poses a danger to humans.<br />
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In the comic Cueball is getting his house inspected; this is common in preparation for selling the home. Inspector Ponytail finds an excessive level of radon in the basement. Often when problems are found in a home, it's due to the age of the building, since technology has improved over time and building codes have added requirements in parallel.<br />
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But rather than inquire about the age of the home, Ponytail asks about the age of the planet on which it was built. The answer would be the same for all houses on Earth.{{cn}} Apparently she's an interplanetary inspector, testing properties on many different planets with different levels of radon - maybe even different solar systems, since most planets in a system form within a few million years of each other. Earth's age of 4.5 billion years is about the same as the half-life of U-238, so radon levels are high because much of the original uranium is still in the process of decaying.<br />
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The sun found in our solar system is an example of a G-type main-sequence star, also known as a yellow dwarf. In 4 to 7 billion years, the Sun's outer layers will expand, turning it into a red giant. This process will render the Earth uninhabitable for humans within approximately 5 billion years.<br />
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The title text for this comic mentions {{w|umbrella insurance}}, which is what insurance companies in the United States pay when the payment extends over their own policies. It makes a joke with the isotope representation of Uranium-238 being <sup>238</sup>U, and is something that Cueball might need to consult with after handling the issue of radon gas in his home; most states in the United States, for instance, require property disclosure forms to be filled out if radon levels surpass a certain threshold.<ref>https://www.eli.org/sites/default/files/files-pdf/Final%202022%20Radon_0.pdf</ref><br />
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==Transcript==<br />
{{incomplete transcript|Do NOT delete this tag too soon.}}<br />
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:[Cueball is on the left, and is approached by Ponytail, who is reading a Geiger counter in her hand and is holding a toolbox in her other hand.]<br />
:Ponytail: Radon levels in your basement are pretty high.<br />
:Ponytail: When was the planet under this home built?<br />
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:[Ponytail stops walking and lowers the Geiger counter]<br />
:Cueball: Uhh, about 4½ billion years ago, I think?<br />
:Ponytail: Oof. I was afraid of that.<br />
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:[A frameless panel]<br />
:Ponytail: This planet was contaminated with uranium when it formed. You really should have let it fully decay before building.<br />
:Ponytail: Wait another 100 billion years and these rocks will be fine.<br />
<br />
:[Zoom in on Cueball's head]<br />
:Cueball: But the Sun will burn out in 5 billion years.<br />
:Ponytail (off-panel): Yikes, you built around a short-lived yellow star? What a mess.<br />
:Ponytail (off-panel): Hope you have good insurance.<br />
==References==<br />
{{reflist}}<br />
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{{comic discussion}}<br />
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[[Category:Comics featuring Cueball]]<br />
[[Category:Comics featuring Ponytail]]<br />
[[Category:Physics]]<br />
[[Category:Chemistry]]<br />
[[Category:Geology]]<br />
[[Category:Astronomy]]</div>Ban me I dare youhttps://www.explainxkcd.com/wiki/index.php?title=1947:_Night_Sky&diff=3620831947: Night Sky2025-01-14T18:42:25Z<p>Ban me I dare you: Replaced content with "{{comic | number = 2 | date = 2 | title = 2 | image = 2.jpg | titletext = 2 }}"</p>
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<div>{{comic<br />
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