r/Damnthatsinteresting • u/anikkundu1998 • Jul 17 '26
Video Earth's gravity isn't perfectly uniform. Here is what our gravitational field looks like when exaggerated 10,000 times.
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u/boipinoi604 Jul 17 '26
No wonder I'm short. Gravity in the Philippines is off the charts.
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u/Jack3024 Jul 17 '26
I was thinking the same thing about all of Southeast Asia, but it looks really high in the northern Atlantic and northern Europe. Aren't those folks known for being pretty tall?
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u/ardotschgi Jul 17 '26
Do you understand what 10000 times exaggeration means? The actual difference is extremely miniscule.
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u/StrategicCheddar Jul 17 '26
The difference in gravity is minuscule so it's not because of that. And shorter people are more dangerous than tall people. A Dutch could trip on you and crack their head open.
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u/jabask Jul 17 '26
It's small but not minuscule ā a full grown man weight like 1.5 lbs more at the North Pole than at the equator.
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u/MineNowBotBoy Jul 17 '26
You must be fun at stand up comedy shows.
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u/allegoryofthedave Jul 17 '26
Stand up comedy is actually much harder in the Philippines.
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u/ARandomNiceKaren Jul 17 '26
I am a ~pushes glasses up~ "but actually" kinda Nerd.
This comment made me huff out of my nose angrily and then laugh.
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u/pimppapy Jul 17 '26
I don't see that very many tall old people. Most people that live into their 90's that I've seen are all shorter.
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u/StoryAndAHalf Jul 17 '26
There's a bunch of kids out there whose moms are so fat, this is how Earth's gravitational field looks like.
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u/RoverBoyNumber6 Jul 17 '26
Your mama is so fat, that when she travels to southern India she balances the globeā¦
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u/glibgloby Jul 17 '26
Your moma is so fat that if you exaggerated earths gravitational field 10,000 times you could see her on the topographic visualization
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u/Lombardyn Jul 17 '26
Your mama so fat, doctors are concerned about her health and longevity. Please talk to her.
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u/bloodem Jul 17 '26
No, because, in that scenario, 99% of gravity would be condensed in the US.
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u/Solnse Jul 17 '26
Your mom lives in the US?
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u/bloodem Jul 17 '26
Partly in the US. The rest of her spills over the Atlantic.
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u/mymoama Jul 17 '26
Lowest gravity is in Peru at 9.7639 m/s and highest at the middle of artic ocean at 9.8337 m/s or a difference of 0.7%
If you could jump 50cm in Peru it wouls equate to 49.8 in the other extream.
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u/blueviper- Jul 17 '26
Interesting. Thank you very much for the share!
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u/Cjprice9 Jul 18 '26
About half of this difference is the fact that you're rotating along with the Earth at "full speed" in Peru, since it's near the equator, and you're not spinning at all at the North Pole. That centripetal force difference maths out to roughly 0.034 m/s2.
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u/Dreadgoat Jul 17 '26
High jump Olympic record is 239cm (set in Atlanta, GA, USA)
+/- 0.7% is a difference of about 1.5cm, significant enough to change history books based on where the Olympics are held, in theory. Obviously there are other factors too, meaning the difference might even be bigger if you find the right locations / times.
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u/ProgrammerCareful764 Jul 18 '26
Do high jumps at high tide in India to utilize both the low gravitational field and the moon's pull on you
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u/totallynotdragonxex Jul 17 '26
I wonder if air pressure/distance above sea level would contribute more or less than this
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u/HapreyCoolie Jul 17 '26
"we have earth at home!"
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u/MickyTingy Jul 17 '26
So we weigh slightly less in the middle of the pacific?
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u/Gingerbread_Cat Jul 17 '26
Excuse me while I sell my house and buy a boat...
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u/DowntownLov Jul 17 '26
Boat still has to be able to hold your weight until you get in the middle, though
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u/canbojack Jul 17 '26
The title is wrong. What is exaggerated is the geoid height. Not the gravity.
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u/shadowraiderr Jul 17 '26
everytime this model gets reposted it gets wrong title/description, morons on facebook will type something like "the earth is not actually round wtf?"
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u/TheStupidLui Jul 17 '26
Technically speaking this is a representation of geoid undulation. Geoid undulation is a diference between global ellipsoid model of Earth (mathematical approximation of Earth's shape) and mean sea level that represents a surface of same gravitational potencial (phisical definition of Earth shape).Ā
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u/qrcjnhhphadvzelota Jul 17 '26
It shows the geoid height, as it says in the caption. But not the gravitational field as mentioned in the post title.
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u/thorheyerdal Jul 17 '26
Didnāt know your mom was vacationing in papua new Guinea.Ā
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u/jess_the_werefox Jul 17 '26
Earth is sphere: ā
Earth is flat: ā
Earth is blob: ā
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u/Icy-Musician-6309 Jul 17 '26
Earth is oblate spheroid:ā
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u/FartSnarfGod Jul 17 '26
Earth's a bloblate bloboid.
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u/qman621 Jul 17 '26
Sourcing your own comment... bold. I'm sold though, calling it a blobate bloboid from now on
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u/Lumpy_Principle3397 Jul 17 '26
Yup! The velocity at the equator and centripetal motion causes the equator to bulge ever so slightly. This makes sense when you consider that the surface of Earth at the equator is traveling over 1000 miles per hour (over 1600 km/h).
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u/Exceedingly Interested Jul 17 '26
Not according to this post. Looks more like a lumpy potato
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u/Choano Jul 17 '26
Are the higher, more orange-y areas the areas with greater gravity? Or with less gravity?
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u/Methoszs Jul 17 '26
Blue is less, orange is higher. I only know because read a story about the Indian ocean having less gravity.
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u/FormerChocoAddict Jul 17 '26 edited Jul 17 '26
Wouldn't this make more sense if it were reversed? Higher gravity pulls the surface down more?Ā
EDIT Folks! The graphic does not provide enough information for the average person to understand what it's showing. The key just indicates the relative exaggerated height. Without prior knowledge people are left to interpret it. My reasoning being that the average person experience is gravity by it pulling them down toward the center of earth. So it is reasonable for a person without a scientific understanding to see this and think 'oh the areas that are closer to the center of Earth is where there is stronger gravity'
I'm sure this graphic was not intended for the general public. It's probably from a scientific paper or something similar. Or at least part of another work that provides more context and explanation. Absent that context or explanation, at the very least this is not clear.Ā
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u/CjBurden Jul 17 '26
This is an image of the gravitational field (magnified significantly), not of the effect gravity is having on things
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u/BitterSweetGoddess53 Jul 17 '26
ya exactly even I thought indian ocean must have a lot of gravity cause the surface is down
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u/RyanSpunk Jul 17 '26
https://en.wikipedia.org/wiki/Geoid
Orange is higher gravity
geoidal height rises where the Earth's material is locally more dense and exerts greater gravitational force than the surrounding areas.
If that sphere were then covered in water, the water would not be the same height everywhere. Instead, the water level would be higher or lower with respect to Earth's center, depending on the integral of the strength of gravity from the center of the Earth to that location. The geoid level coincides with where the water would be. Generally the geoid rises where the Earth's material is locally more dense, exerts greater gravitational force, and pulls more water from the surrounding area.
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u/UKMegaGeek Jul 17 '26
So it's NOT round! /s
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u/Mateorabi Jul 17 '26
Oblique spheroids are still āroundā
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u/RyzRx Jul 17 '26
*Oblate Spheroid
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u/Neshgaddal Interested Jul 17 '26
*Geoid, the most tautological of all the shapes.
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u/NotAcvp3lla Jul 17 '26
Although it might be minimal, does this mean there are places on earth where it's possible for you to age faster?
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u/muclutel Jul 17 '26
Americans have less gravity than Europe and are still heavier.
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u/Cloutian Jul 17 '26
While I understand the concept of this, it should also be compared with relative elevation charts.
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u/Acencguy Jul 17 '26
Now I can tell people, Iām not fat, I just live in a higher gravitational field
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u/Despicable_Wizard Jul 18 '26
Geoid is not gravitational field.... Geoid is the simulated sea level considering the earth irregularities from a ellipsoid
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u/17175RC7 Jul 17 '26
So move to Southern India if I want my scale to show a lower number... got it!
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u/_Monsieur_N Jul 17 '26
Is this a reason for the heights of natives of Papua New Guinea ? Then there must be giants in Sri Lanka ? :/
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u/curious_bipedal Jul 17 '26
Very few things in the Universe are perfectly uniform, under an "exaggerated" scale.
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u/Independent-Fuel-183 Jul 17 '26
I wonder if thereās anything tangible that could be measured or observed in different locations due to this effect?
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u/SubcooledBoiling Jul 17 '26
So what youāre saying is that if a pole vaulter or high jumper wants to break the world record they should attempt it in Sri Lanka?
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u/Topsyye Jul 17 '26
If you exaggerate anything by 10,000 times youāll find that almost everything is not perfectly uniform.
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u/Plenty_Rent_1154 Jul 17 '26
Fun fact: this makes oceans not āflatā ummm.. uniformly curved. So there are really wide āvalleysā and āhillsā on them.
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u/koshgeo Jul 17 '26
There are some important qualifiers here. This is the shape of the geoid, which is an averaged "equipotential surface". As you can see, it is measured as a deviation in metres (above and below a model ellipsoid at the radius of the Earth).
It's not strictly-speaking the strength of the Earth's gravitational field at any one spot, because that is actually more variable at a small scale, and can be influenced by the type of rock immediately beneath you and its density. Those smaller-scale variations are filtered out at this global scale, so it is better to think of this as an averaged or smoothed surface.
The second wrinkle is that the strength of the Earth's gravity also varies with altitude (i.e. as you move away from the mass), which has also been removed to produce a model surface effectively at "sea level", even where you are on land that would be well above sea level. Conceptually, think of it as the shape you would get if you dug a trench across the continent and let the water fill to sea level. The strength of gravity would make it sink a little lower, or rise a little higher. So, it's derived from the strength of gravity, but not strictly-speaking that field directly.
What you actually feel at the surface at any given spot and can measure with instruments as a force will therefore be slightly different, and local effects can overwhelm the regional-scale/smoothed pattern.
This local effect on the gravitational field and deviations from the geoid are useful to measure for all sorts of practical purposes, such as detecting underground voids (caves, tunnels, mines, etc.), masses of magma (generally less dense than surrounding rocks), or for detecting mineral deposits (e.g., metal ore deposits that are usually denser than surrounding rocks).
On the broadest scale as depicted in this video, variations in the geoid are mostly due to variations in the density of the deep, underlying mantle (slightly warmer or slightly cooler -- convection-related features), and plate tectonic things happening closer to the surface (e.g., spreading ridges, rifting, subduction, moutain ranges, etc.).
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u/Healthy-Reserve-1333 Jul 17 '26
Waitā¦ the USA has LOWER gravity? Does this technically make their obese even more obese compared to the obese elsewhere?
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u/pukeface555 Jul 18 '26
You'd think it'd be higher with all the dense mother fuckers that live here .
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u/xGH0STF4CEx Jul 18 '26
My coworker recently told me he saw an article about earth losing gravity for 7 seconds on a certain date and how millions of people were expected to die. He said "idk but it sounded pretty convincing". I honestly didn't know how to reply.
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u/Gfran856 Jul 18 '26
In case anyone was curious, earths gravitational field is directly related to the water bodies. The larger the water body the greater gravitational pull. This is especially so in deep oceans
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u/TheLightDances Jul 18 '26
Upvoted for sharing this data with a title that isn't misleading or false, unlike the hundred times I have seen this before.
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u/halfbeerhalfhuman Jul 17 '26
So less gravity in relativity would equate to time being slower which would equate to living longer. So time to move?
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u/Buerski Jul 17 '26
What is the intensity of this discrepancy with respect to the altitude-latitude gravitational change ? Or is it included ?
The higher in altitude and closer to equator the farther from earth you are and the lower the gravity experienced. I always thought that in the andes for example you experienced lower gravity. In the map it says the contrary, what is it in summary ?
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u/Jill1974 Jul 17 '26
Okay, now I want to know why Papua New Guinea has such high gravity will the gravity in the Indian Ocean is so much lower.
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u/RaEyE01 Jul 17 '26
Less about gravitation than earths surface.
Water smoothes out a lot of these ābumps and dentsā.
But ofc the mass distribution coming with this deformities (compared to the perfect sphere) results in a change of the gravitational field, relative to your position of earths surface.
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u/Cautious-Fudge946 Jul 17 '26
Iām just realizing that the earth would of course not be a perfect sphere
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u/Partosimsa Jul 17 '26
Which of the two mounds is the remnant of Theia?
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u/LetsTwistAga1n Jul 17 '26
None I guess, the remnants of Theia are deep into the mantle (LLSVPs), mantle plumes and lithospheric plate tectonics should affect the shape of the geoid much more. The North Atlantic bulge looks like the result of North Atlantic ocean opening (Iceland hotspot, NAIP, etc.), the negative anomaly near South India is most probably the result of the Indian subcontinent's northward migration, not sure about the SEA anomaly, probably subduction of the Pacific plate or something.
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u/Tiillt Jul 17 '26
So if we are dping the olympics in certain part of the world, is it easier to break records?
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u/TheDevilsAdvokaat Jul 17 '26
Well the field would only be perfectly uniform if the earth was perfectly uniform, including it's internal composition.
Fascinating to see.
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u/Drakore4 Jul 17 '26
Itās not perfectly uniform because the planet isnāt perfectly round. It looks that way because looking from space of course the atmosphere isnāt bumpy or whatever, but the ground solid earth is definitely not a uniform shape.
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u/BattleHall Jul 17 '26 edited Jul 17 '26
As to why this is useful to know: Among other things (oceanography, geology, climate research, etc), if you have a super accurate gravitational map, a super high fidelity real time gravity sensor, and a way to compute and plot your movement in and out of changing gravitational fields, you can use it for navigation or navigational calibration. Which is potentially super useful if you, say, want to stealthily navigate deep under water where GPS signals don't propagate and inertial navigation drifts over time.
https://www.navysbir.com/n09_1/n091-092.htm
Also, one way to map gravity anomalies is to equip two satellites with extremely accurate microwave range finders, then have them chase each other around in orbit and measure the tiny changes in the distance between them as they pass in and out of various gravity variations.
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u/Left-Instruction3885 Jul 17 '26
You sure that's not just us fat ass Americans making our continent dip inwards?
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u/IntegridyFarms Jul 17 '26
High jump should be held in southern India for max height.