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Questions tagged [gravity]

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How to compute spherical harmonics coefficients using orthogonality?

I use the lunar gravity model GRGM900C to calculate the gravitational potential across a $360{^\circ}*360{^\circ}$ grid. This calculation follows the equation: $$V(\varphi,\lambda)=\sum_{\mathrm{n=0}}^...
Picaqiu's user avatar
  • 21
1 vote
0 answers
63 views

Why does weaker local gravity cause lower sea level?

The weaker local gravity in the Indian Ocean geoid low (IOGL) causes the sea level to be 106 m below the global mean sea level. Why is that ? "Because of this lower density, the gravitational ...
summerrain's user avatar
0 votes
1 answer
121 views

Which forces align objects with the rotation of the Earth and how?

I have a question about which forces cause alignment of objects with the rotation of the Earth and how: It is known to me from public sources that objects up to a height of about 36,000 meters above ...
Jakub Jelinek's user avatar
0 votes
1 answer
113 views

Do gravity and magnetic field change along a geographic latitude or not?

Along the same geographic latitude does magnetic field change or not, and the same for the gravitational field, does it change along a geographic latitude? Please explain.
Ankit Rathore's user avatar
0 votes
1 answer
95 views

What is a general formula for Earth gravity as a function of radius, given a spherical shell model?

I'm trying to derive the formula for gravitational acceleration as a function of Earth radius $g(r)$, given a spherical shell model where each shell has a constant density $\rho(r)$. If I set $r=0$ to ...
co323's user avatar
  • 3
1 vote
0 answers
34 views

Why is there a low gravity anomaly right next to a high gravity anomaly next to mascons on the Moon?

This is from the book "Isosatsy and Flexure of the Atmosphere" by A. B. Watts. According to him, evidence for the isostatic compensation of mascons (i.e. regions of higher density material ...
Justus Otter's user avatar
6 votes
1 answer
236 views

Why is sealevel higher where gravity is higher?

The EGM96 geoid map depicts hypothetical sealevel due to gravitational variations on the Earth's surface: image source It places one of the highest areas in the northern part of the Atlantic ocean. ...
Jason C's user avatar
  • 160
5 votes
8 answers
3k views

How is the atmosphere expanding in all directions if Gravity is holding the atmosphere down to earth?

We are taught that gravity is the force that keeps the atmosphere and everything else binded to Earth. However, observable reality shows us that the atmosphere expands in all directions as it fills ...
That Guy's user avatar
3 votes
1 answer
65 views

Do the 600 satellites that orbit the Earth have any gravitational pull on the tides like the moon?

I know that space is big and satellites are small compared with the moon, but do they have, or will they if we get more, any effect on the sea and ocean water on the earth?
rhett's user avatar
  • 121
1 vote
0 answers
29 views

Would obliquity and precessional changes of Earth affect the accuracy of GPS-based measurement of tectonic movements?

The rate and direction of tectonic movements can be measured by comparing the coordinates of the same GPS receiver over time. The coordinates are obtained using trilateration. All materials I could ...
seamos's user avatar
  • 51
1 vote
1 answer
79 views

How might 25% lower gravity affect precipitation on an Earth-like planet? [closed]

I'm working on a science fiction project and hoping someone who knows something about climate can answer this question for me: if Earth had 25% less gravity, how would that affect precipitation? I ...
Elhammo's user avatar
  • 233
3 votes
1 answer
213 views

Expression for the gradient of gravity potential in spherical coordinates

I am currently using the GGM05C Stokes' coefficients to reconstruct the gradient of gravity potential of Earth. I have found an expression for said gradient in spherical coordinates in this technical ...
Rafa's user avatar
  • 233
4 votes
1 answer
73 views

Why do ocean tides have negative and positive terms in their effects on Stoke's coefficients for calculating geopotential?

I have recently started working on calculating a Geopotential model based on GGM05C. In order to obtain a model as accurate as possible, some corrections must be applied to the normalized Stokes' ...
Rafa's user avatar
  • 233
18 votes
5 answers
11k views

What is the pressure at the center of the Earth?

In the question Does gravity increase the closer to the core you get?, it was determined that gravity reduces to zero at the center of the Earth. That is logical. However if pressure is proportional ...
ralph ellis's user avatar
1 vote
2 answers
2k views

Why does the moon orbit the earth and not the sun instead? [closed]

Objects orbit the sun because of the sun's gravity, and Earth's gravity is weaker than the sun's gravitational pull. So why does the moon orbit the Earth instead of the sun?
yor's user avatar
  • 43
4 votes
2 answers
308 views

Does the Earth produces measurable gravity waves?

Does the Earth exhibit measurable gravity waves? Note: I'm not asking about gravitational waves. Some recent experiments looking at low-frequency (3$\times 10^{-5}$Hz) accelerometer data are showing ...
Sparks's user avatar
  • 51
2 votes
0 answers
35 views

Learn geological properties of the horizon through density of the rocks

It is possible to evaluate the geological structure of a basin based on gravimetric data. But if one doesn't have gravimetric data, how can one learn the geological structure and properties of a ...
student0434's user avatar
3 votes
0 answers
73 views

How are mGal-smooth free-air gravity anomaly measurements made exactly? (tiny variations of acceleration on a bumpy airplane ride)

Free-air gravity anomaly measurements from Operation Icebridge aircraft are described in A fault-bounded palaeo-lake basin preserved beneath the Greenland Ice Sheet (open access). Question: These ...
uhoh's user avatar
  • 7,072
5 votes
0 answers
81 views

How do you choose appropriate parameters for a lowpass filter when filtering a Bouguer anomaly?

I am trying to filter my Bouguer anomaly data to remove the short wavelength features. I have created a lowpass filter to achieve this, but I am wondering how I can more objectively choose my cutoff ...
Jet Yeti's user avatar
6 votes
1 answer
853 views

How to make a Python function return the Moon's gravitational force (acceleration) to calculate orbits?

The Space SE question How much does it cost to land on a lunar mascon? includes the background information below. I am sure it's not too hard to find a link where spherical harmonic coefficients for ...
uhoh's user avatar
  • 7,072
1 vote
1 answer
72 views

Why isn't the acceleration of an object in Earth's gravity related to the object's mass? [closed]

Why isn't the acceleration of an object in Earth's gravity related to the object's mass? Please, try to explain this effect without physical formulas, but using only logical formulation.
Ahillesius's user avatar
36 votes
3 answers
16k views

Does gravity increase the closer to the core you get?

Or does the mantle and crust above you counteract the increase at one point and it actually decreases?
HingedHD's user avatar
  • 484
5 votes
3 answers
7k views

Are we experiencing lower level of gravity now compared to past?

Whole civilizations have been buried underground and we have built new landscapes over them. The fact that tall buildings and houses are being excavated from under the ground means that we are living ...
Bej's user avatar
  • 199
3 votes
3 answers
630 views

If the Earth's core were made up of copper/other metals other than iron-nickel alloy, what would the magnetosphere be like?

We know that our earth's core is made up of iron-nickel alloy, and it is spinning to create magnetic flux all around our planet to create our life-saving Magnetosphere. And this also influences our 9....
Kautham Krishna's user avatar
1 vote
1 answer
255 views

How was the Earth's core made?

All I've heard until now is that when the Earth was very hot and slimy, the relatively heavier elements went down to the center of the Earth to form the core. But lately I've come up a contradiction ...
dolco's user avatar
  • 113
4 votes
1 answer
74 views

Realtime planetary gravity maps?

I'm trying to find maps of realtime (or at least periodically updated / semi-realtime) gravity maps of Earth. I was hoping that GOCE might have something like this available, but I've been hitting a ...
ylluminate's user avatar
5 votes
1 answer
713 views

How much energy does the Moon transfer to the Earth, does this affect the Earth's surface temperature?

I'm wondering by how much the gravitation effects, tides etc caused by the moon (and other energy such as moonlight IR) increase the surface temperature of the Earth. So how much warmer than the ...
Andy's user avatar
  • 83
5 votes
2 answers
437 views

Why doesn't Wolfram Alpha show low gravitational acceleration for the Hudson Bay?

I thought I would be clever and add a new answer to Hudson Bay Has Low Gravity? by using Wolfram Alpha to report gravitational acceleration for different locations, but it looks like my cleverness ...
uhoh's user avatar
  • 7,072
1 vote
0 answers
36 views

Detailed gravity maps

Does anyone know if it is possible to get a gravity map of a specific region of Greenland? The data I've found here http://icgem.gfz-potsdam.de/vis3d/longtime , are simply of to low spatial ...
Mars's user avatar
  • 111
-1 votes
3 answers
631 views

Variations in Gravity over Time

Is there any consensus about the conjecture that gravitational force on Earth may have changed significantly over geological time; and in particular in periodic increase associated with mass ...
james everitt's user avatar
12 votes
4 answers
4k views

Hudson Bay Has Low Gravity?

Is there lower gravity at the Hudson Bay? How does this happen? And where exactly is this because I might want to go.
user avatar
7 votes
1 answer
226 views

Can anyone explain the torque that causes the Earth's axial precession?

Looking around on the web, I frequently see explanations like "precession is caused by the action of the Sun's gravity on the Earth's equatorial bulge." That's nice, but I'm interested in a little ...
William Jockusch's user avatar
5 votes
2 answers
673 views

Plate Tectonics vs Gravity for Creating Highs and Lows

I have a question that I thought of when discussing a Worldbuilding scenario here. In that question, a super earth with gravity 1.35 times that of earth's is discussed, and is assumed to have shallow ...
user3390629's user avatar
0 votes
1 answer
521 views

If Earth had rings would gravity exerted by Earth decrease?

If Earth had enough mass in its own rings, more than the weight of Earth: What could it decrease the gravity to? Would the atmosphere have more depth or be thinner? What would the weather be like? ...
Muze's user avatar
  • 1
12 votes
1 answer
2k views

What is the fastest the Earth has ever spun?

How fast can the Earth rotate and support life? In prehistoric times, dinosaurs were so massive that archeologists wonder how they were not crushed under their own weight. Could a faster spinning ...
Muze's user avatar
  • 1
5 votes
1 answer
589 views

How high is too high for hydrogen to rise?

If hydrogen is the lightest gas known, would it rise making the outermost part of the atmosphere mostly hydrogen? Images to associate with your answer would be much appreciated. Thanks
Muze's user avatar
  • 1
3 votes
1 answer
318 views

A balloon falling from space?

How long would it take for a store bought rubber balloon filled in space with air to fall from space just outside the atmosphere and touch ground? Would it Pop? Added after comments: Ideally you ...
Muze's user avatar
  • 1
4 votes
1 answer
179 views

What would be the depth variation of a "water ellipsoid" above a reference ellipsoid Earth?

The question If the Earth was a smooth spheroid how deep would be the ocean? has an excellent answer which explains the shape and surface area of an oblate spheroid before calculating the average ...
uhoh's user avatar
  • 7,072
2 votes
0 answers
87 views

Are ramp pumps the solution to the global water problem? [closed]

For the past few years people have been trying to solve the global water problem (especially in Africa), and what better way than being echo friendly. So my question is, can you use the tidal energy ...
Jaks's user avatar
  • 29
4 votes
2 answers
5k views

What does the degree and order of Spherical Harmonics mean?

I've been reading up about Gravitational Models and Spherical Harmonics. Where I first read about them is in this scholarly article on Autonomous navigation with Gravity Gradients. It talks about ...
Edlothiad's user avatar
  • 143
2 votes
0 answers
42 views

Phase of S2 constituent in tidal prediction

I ran the ETERNA code for the prediction of tidal gravity at some station. Then I use Fourier analysis to recover the amplitude and phase of the S2 constituent. As I understand, the phase of the S2 ...
Ruifeng Dong's user avatar
3 votes
1 answer
2k views

How much do tides affect earth's rotational velocity?

Many of us are familiar with an exaggerated picture of the Moon's effect on Earth's tides: Since the Earth is not uniformly covered with water, however, I imagine that the tidal effect will depend on ...
Ben Sandeen's user avatar
7 votes
1 answer
3k views

Compute direction of gravity vector

As I understand to compute vector of gravity not saficient to compute normal to elipsoid, but we need to computer normal to geoid (by definition geoid is a surface to which the force of gravity is ...
mrgloom's user avatar
  • 173
11 votes
4 answers
9k views

Does gravity differ from place to place on Earth

Does a particular object have the same weight on every part of Earth or does it vary?
John's user avatar
  • 628
9 votes
2 answers
1k views

Terrain correction for gravity data using Nagy, 1973

I am working with an algorithm for terrain correction of gravity data. I am using Nagy, 1973. However, I could not get the results I need. So, this is the problem. I have this function where x,y,z ...
jaime garbanzo's user avatar
12 votes
2 answers
1k views

Change in earth mass since the time of the dinosaurs

Is there a significant difference in the mass of the Earth between now and the time of the dinosaurs (250 - 75 million years ago)? I was just wondering if the force of gravity on dinosaurs would have ...
Brian M. Hunt's user avatar