https://www.explainxkcd.com/wiki/api.php?action=feedcontributions&feedformat=atom&user=2605%3A59C8%3A160%3ADB08%3A5509%3A55F4%3A1094%3A998B 2026-06-04T10:19:57Z User contributions MediaWiki 1.30.0 https://www.explainxkcd.com/wiki/index.php?title=3135:_Sea_Level&diff=385617 2025-08-30T14:31:52Z

<p>2605:59C8:160:DB08:5509:55F4:1094:998B: </p> <hr /> <div>{{comic<br /> | number = 3135<br /> | date = August 29, 2025<br /> | title = Sea Level<br /> | image = sea_level_2x.png<br /> | imagesize = 321x453px<br /> | noexpand = true<br /> | titletext = They're up there with coral islands, lightning, and caterpillars turning into butterflies.<br /> }}<br /> <br /> ==Explanation==<br /> {{incomplete|This page was created by A FRIENDLY TIDAL WAVE. Don't remove this notice too soon.}}<br /> In this comic [[Cueball]] is wondering aloud what happened to an island, possibly a {{w|sandbar}} that was visible earlier, but is not anymore. [[Megan]] explains to him that the {{w|tide}} has gone up, and thus the island is underwater. She then tells him about what causes tides, namely the {{w|Moon}}, which is large enough and orbits close enough to Earth to gravitationally affect the waters of our oceans, causing them to go up and down daily. Similarly to [[2809: Moon]], Cueball is amazed at the oddity of our planet having a natural satellite large enough to affect our oceans, and Randall seems to be as well, as the caption says that if the Moon didn't exist, it would sound extremely outlandish and sci-fi-like.<br /> <br /> {{w|Tide|Tides}} on Earth would indeed seem strange and unusual to a visitor from almost anywhere else in the universe, along with other features such as the large expanses of liquid water and the oxygen-rich atmosphere that was created by biological activity (photosynthesis). Not to mention the biological activity. As stated in the comic, tides on Earth are largely the result of a single large moon (''the'' Moon) orbiting the Earth at a relatively short distance. This configuration is {{w|List_of_natural_satellites|unique within our solar system}}: Mercury and Venus have no moons, Mars (smaller than Earth) has two, and each of the remaining planets has several. If the Moon were absent from Earth orbit, tidal amplitudes would be much less, because the Sun's gravity has much less influence on Earth's liquid water masses than the Moon does. Also, if more than one moon were present, or the moon(s) present had much less mass, or the moon(s) present had more distant orbits, tides would have less amplitude, and, in the case of multiple moons, would have much more complex (and possibly difficult to predict) periodicity.<br /> <br /> &lt;!-- THIS WAS SUPPOSED TO BE SHORTER The single Moon creates tides that, with a few minor complications due to seabed/landmass topology an obliquely lessened effect at extreme latitudes, typically go through two full cycles every 24 hours and 50 minutes. Over the course of slightly over a day, the Moon passes roughly over every point once, drawing the water into a 'bulge' towards it, and at exactly half way round the Earth it effectively exerts less pull on the now-far-side water than it does on the Earth itself, which manifests as a second bulge of water/high-tide. The parts of the planet perpendicular to the Earth-Moon line 'lose' water to Moonwards/Moon-opposing bulges, as best as the constriction points around the various seas and oceans allow, to produce lower water levels than average. The tidal influence of the Sun (which, alone, would create two lesser high tides every solar day, by the same mechanism, which therefore adds or removes some tidal height. As a rule, around the time when a New Moon or Full Moon is in the daytime or night-time sky, the lunar tide is reinforced by the effect of the solar tide, whereas when a half-lit moon (&quot;first/last quarter&quot;) is in the sky, the lunar tide is mitigated by the Sun's lesser tendency to ease the water away from the Moon's high-bulges and into its low-troughs. MAYBE SOMETHING USEFUL IN THERE, THOUGH --&gt;The overall effect of the Moon-dominated tides is that in marginally more than every 6.2 hours (at least for an ocean-dominated equatorial island, such as the comic appears to depict) something that was originally fully revealed by a retreating tide could now be covered be the next rising one. This effect is even more pronounced every 14.75 days, as the Moon and Sun act together to create even higher high tides and lower low tides. Anyone used to the behaviour of the sea would probably be unsurprised by this, but someone normally resident more inland can quite easily be caught out, potentially arriving somewhere by the coast in the morning, to witness the sight of particularly low water levels, then by noon/early-afternoon finding that the seascape has changed and high-water has been reached.<br /> <br /> The title text mentions other outlandish phenomena on Earth, comparing them to tides, including {{w|coral islands}}, islands that build up on top of coral reefs out of coral detritus and other natural materials, {{w|lightning}}, when electrical charges come racing down from thunderclouds in a bright flash of light, and the {{w|metamorphosis}} of {{w|butterflies}}, when caterpillars create a chrysalis and come out as butterflies. Unlike coral islands and metamorphosis, which, so far as humans know, are unique to Earth, lightning has been found elsewhere; within our solar system, it [https://science.nasa.gov/science-research/planetary-science/lightning-across-the-solar-system/ occurs on Jupiter, Saturn, and possibly Mars].<br /> <br /> ==Transcript==<br /> {{incomplete transcript|Don't remove this notice too soon.}}<br /> <br /> :[Single frame, with Megan and Cueball standing at a coastline, with water and waves visible.]<br /> <br /> :Cueball: Hey, where's that big island we were looking at this morning?<br /> :Megan: Oh, it's underwater. The ocean's depth here goes up and down by like ten feet every day.<br /> :Cueball: What?<br /> :Megan: It's because the planet has a big moon orbiting near the surface. It causes weird gravity effects.<br /> :Cueball: '''What???'''<br /> <br /> :[Caption below the frame:]<br /> :People here are used to them, but tides are one of the weirdest and most sci-fi elements of life on Earth.<br /> <br /> {{comic discussion}}&lt;noinclude&gt;<br /> [[Category: Comics featuring Cueball]]<br /> [[Category: Comics featuring Megan]]<br /> [[Category: Astronomy]]</div>

2605:59C8:160:DB08:5509:55F4:1094:998B https://www.explainxkcd.com/wiki/index.php?title=3135:_Sea_Level&diff=385616 2025-08-30T14:29:44Z

<p>2605:59C8:160:DB08:5509:55F4:1094:998B: </p> <hr /> <div>{{comic<br /> | number = 3135<br /> | date = August 29, 2025<br /> | title = Sea Level<br /> | image = sea_level_2x.png<br /> | imagesize = 321x453px<br /> | noexpand = true<br /> | titletext = They're up there with coral islands, lightning, and caterpillars turning into butterflies.<br /> }}<br /> <br /> ==Explanation==<br /> {{incomplete|This page was created by A FRIENDLY TIDAL WAVE. Don't remove this notice too soon.}}<br /> In this comic [[Cueball]] is wondering aloud what happened to an island, possibly a {{w|sandbar}} that was visible earlier, but is not anymore. [[Megan]] explains to him that the {{w|tide}} has gone up, and thus the island is underwater. She then tells him about what causes tides, namely the {{w|Moon}}, which is large enough and orbits close enough to Earth to gravitationally affect the waters of our oceans, causing them to go up and down daily. Similarly to [[2809: Moon]], Cueball is amazed at the oddity of our planet having a natural satellite large enough to affect our oceans, and Randall seems to be as well, as the caption says that if the Moon didn't exist, it would sound extremely outlandish and sci-fi-like.<br /> <br /> {{w|Tide|Tides}} on Earth would indeed seem strange and unusual to a visitor from almost anywhere else in the universe, along with other features such as the large expanses of liquid water and the oxygen-rich atmosphere that was created by biological activity (photosynthesis). Not to mention the biological activity. As stated in the comic, tides on Earth are largely the result of a single large moon (''the'' Moon) orbiting the Earth at a relatively short distance. This configuration is {{w|List_of_natural_satellites|unique within our solar system}}: Mercury and Venus have no moons, Mars (smaller than Earth) has two, and each of the remaining planets has several. If the Moon were absent from Earth orbit, tidal amplitudes would be much less, because the Sun's gravity has much less influence on Earth's liquid water masses than the Moon does. Also, if more than one moon were present, or the moon(s) present were much less massive, or the moon(s) present had more distant orbits, tides would have less amplitude, and, in the case of multiple moons, would have much more complex (and possibly difficult to predict) periodicity.<br /> <br /> &lt;!-- THIS WAS SUPPOSED TO BE SHORTER The single Moon creates tides that, with a few minor complications due to seabed/landmass topology an obliquely lessened effect at extreme latitudes, typically go through two full cycles every 24 hours and 50 minutes. Over the course of slightly over a day, the Moon passes roughly over every point once, drawing the water into a 'bulge' towards it, and at exactly half way round the Earth it effectively exerts less pull on the now-far-side water than it does on the Earth itself, which manifests as a second bulge of water/high-tide. The parts of the planet perpendicular to the Earth-Moon line 'lose' water to Moonwards/Moon-opposing bulges, as best as the constriction points around the various seas and oceans allow, to produce lower water levels than average. The tidal influence of the Sun (which, alone, would create two lesser high tides every solar day, by the same mechanism, which therefore adds or removes some tidal height. As a rule, around the time when a New Moon or Full Moon is in the daytime or night-time sky, the lunar tide is reinforced by the effect of the solar tide, whereas when a half-lit moon (&quot;first/last quarter&quot;) is in the sky, the lunar tide is mitigated by the Sun's lesser tendency to ease the water away from the Moon's high-bulges and into its low-troughs. MAYBE SOMETHING USEFUL IN THERE, THOUGH --&gt;The overall effect of the Moon-dominated tides is that in marginally more than every 6.2 hours (at least for an ocean-dominated equatorial island, such as the comic appears to depict) something that was originally fully revealed by a retreating tide could now be covered be the next rising one. This effect is even more pronounced every 14.75 days, as the Moon and Sun act together to create even higher high tides and lower low tides. Anyone used to the behaviour of the sea would probably be unsurprised by this, but someone normally resident more inland can quite easily be caught out, potentially arriving somewhere by the coast in the morning, to witness the sight of particularly low water levels, then by noon/early-afternoon finding that the seascape has changed and high-water has been reached.<br /> <br /> The title text mentions other outlandish phenomena on Earth, comparing them to tides, including {{w|coral islands}}, islands that build up on top of coral reefs out of coral detritus and other natural materials, {{w|lightning}}, when electrical charges come racing down from thunderclouds in a bright flash of light, and the {{w|metamorphosis}} of {{w|butterflies}}, when caterpillars create a chrysalis and come out as butterflies. Unlike coral islands and metamorphosis, which, so far as humans know, are unique to Earth, lightning has been found elsewhere; within our solar system, it [https://science.nasa.gov/science-research/planetary-science/lightning-across-the-solar-system/ occurs on Jupiter, Saturn, and possibly Mars].<br /> <br /> ==Transcript==<br /> {{incomplete transcript|Don't remove this notice too soon.}}<br /> <br /> :[Single frame, with Megan and Cueball standing at a coastline, with water and waves visible.]<br /> <br /> :Cueball: Hey, where's that big island we were looking at this morning?<br /> :Megan: Oh, it's underwater. The ocean's depth here goes up and down by like ten feet every day.<br /> :Cueball: What?<br /> :Megan: It's because the planet has a big moon orbiting near the surface. It causes weird gravity effects.<br /> :Cueball: '''What???'''<br /> <br /> :[Caption below the frame:]<br /> :People here are used to them, but tides are one of the weirdest and most sci-fi elements of life on Earth.<br /> <br /> {{comic discussion}}&lt;noinclude&gt;<br /> [[Category: Comics featuring Cueball]]<br /> [[Category: Comics featuring Megan]]<br /> [[Category: Astronomy]]</div>

2605:59C8:160:DB08:5509:55F4:1094:998B https://www.explainxkcd.com/wiki/index.php?title=3135:_Sea_Level&diff=385605 2025-08-30T03:03:08Z

<p>2605:59C8:160:DB08:5509:55F4:1094:998B: </p> <hr /> <div>{{comic<br /> | number = 3135<br /> | date = August 29, 2025<br /> | title = Sea Level<br /> | image = sea_level_2x.png<br /> | imagesize = 321x453px<br /> | noexpand = true<br /> | titletext = They're up there with coral islands, lightning, and caterpillars turning into butterflies.<br /> }}<br /> <br /> ==Explanation==<br /> {{incomplete|This page was created by A FRIENDLY TIDAL WAVE. Don't remove this notice too soon.}}<br /> In this comic [[Cueball]] is wondering aloud what happened to an island, possibly a {{w|sandbar}} that was visible earlier, but is not anymore. [[Megan]] explains to him that the {{w|tide}} has gone up, and thus the island is underwater. She then tells him about what causes tides, namely the {{w|moon}}, which is large enough and orbits close enough to Earth to gravitationally affect the waters of our oceans, causing them to go up and down daily. Similarly to [[2809: Moon]], Cueball is amazed at the oddity of our planet having a natural satellite large enough to affect our oceans, and Randall seems to be as well, as the caption says that if the moon didn't exist, it would sound extremely outlandish and sci-fi-like.<br /> <br /> {{w|Tide|Tides}} on Earth would indeed seem strange and unusual to a visitor from almost anywhere else in the universe, along with other features such as the large expanses of liquid water and the oxygen-rich atmosphere that was created by biological activity (photosynthesis). Not to mention the biological activity. As stated in the comic, tides on Earth are largely the result of a single large moon (the Moon) orbiting the Earth at a relatively short distance. If the Moon were absent, tidal amplitudes would be much less, because the Sun's gravity has much less influence on Earth's liquid water masses than the Moon does. Also, if more than one moon were present, or the moon(s) present were much less massive, or the moon(s) present had more distant orbits, tides would have less amplitude, and, in the case of multiple moons, would have much more complex (and possibly difficult to predict) periodicity.<br /> <br /> The title text mentions other outlandish phenomena on Earth, comparing them to tides, including {{w|coral islands}}, islands that build up on top of coral reefs out of coral detritus and other natural materials, {{w|lightning}}, when electrical charges come racing down from thunderclouds in a bright flash of light, and the {{w|metamorphosis}} of {{w|butterflies}}, when caterpillars create a chrysalis and come out as butterflies. Unlike coral islands and metamorphosis, which, so far as humans know, are unique to Earth, lightning has been found elsewhere; within our solar system, it [https://science.nasa.gov/science-research/planetary-science/lightning-across-the-solar-system/ occurs on Jupiter, Saturn, and possibly Mars].<br /> <br /> ==Transcript==<br /> {{incomplete transcript|Don't remove this notice too soon.}}<br /> <br /> [Single frame, with Megan and Cueball standing at a coastline, with water and waves visible.]<br /> <br /> Cueball: Hey, where's that big island we were looking at this morning?<br /> <br /> Megan: Oh, it's underwater. The ocean's depth here goes up and down by like ten feet every day.<br /> <br /> Cueball: What?<br /> <br /> Megan: It's because the planet has a big moon orbiting near the surface. It causes weird gravity effects.<br /> <br /> Cueball: '''What???'''<br /> <br /> Caption below the frame: People here are used to them, but tides are one of the weirdest and most sci-fi elements of life on Earth.<br /> <br /> {{comic discussion}}&lt;noinclude&gt;</div>

2605:59C8:160:DB08:5509:55F4:1094:998B https://www.explainxkcd.com/wiki/index.php?title=3135:_Sea_Level&diff=385604 2025-08-30T02:56:26Z

<p>2605:59C8:160:DB08:5509:55F4:1094:998B: </p> <hr /> <div>{{comic<br /> | number = 3135<br /> | date = August 29, 2025<br /> | title = Sea Level<br /> | image = sea_level_2x.png<br /> | imagesize = 321x453px<br /> | noexpand = true<br /> | titletext = They're up there with coral islands, lightning, and caterpillars turning into butterflies.<br /> }}<br /> <br /> ==Explanation==<br /> {{incomplete|This page was created by A FRIENDLY TIDAL WAVE. Don't remove this notice too soon.}}<br /> In this comic [[Cueball]] is wondering aloud what happened to an island, possibly a {{w|sandbar}} that was visible earlier, but is not anymore. [[Megan]] explains to him that the {{w|tide}} has gone up, and thus the island is underwater. She then tells him about what causes tides, namely the {{w|moon}}, which is large enough and orbits close enough to Earth to gravitationally affect the waters of our oceans, causing them to go up and down daily. Similarly to [[2809: Moon]], Cueball is amazed at the oddity of our planet having a natural satellite large enough to affect our oceans, and Randall seems to be as well, as the caption says that if the moon didn't exist, it would sound extremely outlandish and sci-fi-like.<br /> <br /> {{w|Tide|Tides}} on Earth would indeed seem strange and unusual to a visitor from almost anywhere else in the universe, along with other features such as the large expanses of liquid water and the oxygen-rich atmosphere that was created by biological activity (photosynthesis). Not to mention the biological activity. As stated in the comic, tides on Earth are largely the result of a single large moon (the Moon) orbiting the Earth at a relatively short distance. If the Moon were absent, tidal amplitudes would be much less, because the Sun's gravity has much less influence on Earth's liquid water masses than the Moon does. Also, if more than one moon were present, or the moon(s) present were much less massive, or the moon(s) present had more distant orbits, tides would have less amplitude, and, in the case of multiple moons, would have much more complex (and possibly difficult to predict) periodicity.<br /> <br /> The title text mentions other outlandish phenomenons on Earth, comparing them to tides, including {{w|coral islands}}, islands that build up on top of coral reefs out of coral detritus and other natural materials, {{w|lightning}}, when electrical charges come racing down from thunderclouds in a bright flash of light, and the {{w|metamorphosis}} of {{w|butterflies}}, when caterpillars create a chrysalis and come out as butterflies. Unlike coral islands and metamorphosis, which, so far as humans know, are unique to Earth, lightning has been found elsewhere; within our solar system, it [https://science.nasa.gov/science-research/planetary-science/lightning-across-the-solar-system/ occurs on Jupiter, Saturn, and possibly Mars].<br /> <br /> ==Transcript==<br /> {{incomplete transcript|Don't remove this notice too soon.}}<br /> <br /> [Single frame, with Megan and Cueball standing at a coastline, with water and waves visible.]<br /> <br /> Cueball: Hey, where's that big island we were looking at this morning?<br /> <br /> Megan: Oh, it's underwater. The ocean's depth here goes up and down by like ten feet every day.<br /> <br /> Cueball: What?<br /> <br /> Megan: It's because the planet has a big moon orbiting near the surface. It causes weird gravity effects.<br /> <br /> Cueball: '''What???'''<br /> <br /> Caption below the frame: People here are used to them, but tides are one of the weirdest and most sci-fi elements of life on Earth.<br /> <br /> {{comic discussion}}&lt;noinclude&gt;</div>

2605:59C8:160:DB08:5509:55F4:1094:998B https://www.explainxkcd.com/wiki/index.php?title=3135:_Sea_Level&diff=385593 2025-08-30T01:52:05Z

<p>2605:59C8:160:DB08:5509:55F4:1094:998B: </p> <hr /> <div>{{comic<br /> | number = 3135<br /> | date = August 29, 2025<br /> | title = Sea Level<br /> | image = sea_level_2x.png<br /> | imagesize = 321x453px<br /> | noexpand = true<br /> | titletext = They're up there with coral islands, lightning, and caterpillars turning into butterflies.<br /> }}<br /> <br /> ==Explanation==<br /> {{incomplete|This page was created by A FRIENDLY TIDAL WAVE. Don't remove this notice too soon.}}<br /> In this comic [[Cueball]] is wondering aloud what happened to an island, possibly a {{w|sandbar}} that was visible earlier, but is not anymore. [[Megan]] explains to him that the {{w|tide}} has gone up, and thus the island is underwater. She then tells him about what causes tides, namely the {{w|moon}}, which is large enough and orbits close enough to Earth to gravitationally affect the waters of our oceans, causing them to go up and down daily. Similarly to [[2809: Moon]], Cueball is amazed at the oddity of our planet having a natural satellite large enough to affect our oceans, and Randall seems to be as well, as the caption says that if the moon didn't exist, it would sound extremely outlandish and sci-fi-like.<br /> <br /> {{w|Tide|Tides}} on Earth would indeed seem strange and unusual to a visitor from almost anywhere else in the universe, along with other features such as the large expanses of liquid water and the oxygen-rich atmosphere that was created by biological activity (photosynthesis). Not to mention the biological activity. As stated in the comic, tides on Earth are largely the result of a single large moon (the Moon) orbiting the Earth at a relatively short distance. If the Moon were absent, tidal amplitudes would be much less, because the Sun's gravity has much less influence on Earth's liquid water masses than the Moon does. Also, if more than one moon were present, or the moon(s) present were much less massive, or the moon(s) present had more distant orbits, tides would have less amplitude, and, in the case of multiple moons, would have much more complex (and possibly difficult to predict) periodicity.<br /> <br /> The title text compares tides to other unusual, and possibly unique, features of Earth, two of which (coral reefs and {{w|Metamorphosis#Insects|the developmental biology of insects}}) are components of Earth's biological activity.<br /> <br /> ==Transcript==<br /> {{incomplete transcript|Don't remove this notice too soon.}}<br /> <br /> {{comic discussion}}&lt;noinclude&gt;</div>

2605:59C8:160:DB08:5509:55F4:1094:998B