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147

This is an interesting question, but it lacks a key factor that is crucial to the answer: TIME. The point on Earth closest to the Sun varies through time, so the question can be asked about any moment in time, or over periods of time. Let's analyze the factors involved. At any given moment in time, the point on Earth's surface that is closest to the Sun is ...


18

Normally in the absence of rotation, the natural tenancy of gravity is to pull the Earth together in the shape of a sphere. However the Earth in fact bulges at the equator, and the diameter across the equatorial plane is 42.72 km more than the diameter from pole to pole. This is due to the rotation of the Earth. As we can see in the image above, the ...


11

Actually, the reason why the Earth is not a sphere is twofold: the Earth is rotating and has been rotating for a long time the Earth is not perfectly rigid, it can even be considered as a viscous fluid on long timescales If the Earth were not rotating, it would be a sphere. If the Earth had started to rotate very recently, it wouldn't be at equilibrium, ...


10

It is impossible to know. Solar flares can have more than 500,000 kilometers. So if we consider them part of the sun, the moment when the earth is closer to the sun can be very different from perihelion if a big flare happens, making much of what was discussed in other answers irrelevant.


10

One way to approach this is to treat the Earth as an oblate ellipsoid. This would mean the errors arise from the uncertainties in the Earth's equatorial radius and the flattening. From Groten, "Fundamental Parameters and Current (2004) Best Estimates of the Parameters of Common Relevance to Astronomy, Geodesy, and Geodynamics," Journal of Geodesy 77:10-11, ...


7

Talking about the volume of the Earth, we have to ignore that it is not static but in fact highly dynamic. The tides alone make the height differ by up to 50 cm. The information I take is from a 2003 article from esri by Witold Fraczek. As you said, we have different understandings of the Earth. Approximations are made to make calculations easier (and ...


6

In short, the current volume of the earth is known to great precision and modern measurements show no significant expansion at meaningful scales. Facing 20th century evidence that points on the globe -- such as the edges of continents -- that are now distant from each other were once adjacent, some scientists argued that the only explanation was the ongoing ...


6

The centre of the Earth is the only true unchanging datum. Land masses rise and fall due to geological actions such as melting of land based ice sheets, volcanism, plate tectonics, erosion, sedimentation and ground stresses causing land masses to move relative to one another at faults. As stated here, sea level changes resulting from, Eustatic change (...


6

These are visco-elastic oscillations that cause virtually no permanent deformation. Following the Tohoku 2011 earthquake, this gravimeter in Metsähovi, Finland, measured a radial oscillation mode amplitude of 0.06 mm. The Earth's radius is 6371 km. So the resulting strains would be extremely small. All but the lowest radial mode decays after a few days ...


5

That the Earth is approximately an oblate spheroid is best explained by energy. Place a marble in a bowl. No matter where you place it, it will eventually come to rest at the bottom of the bowl. This is the position that minimizes the total energy of the marble subject to the constraint of being in the bowl. Suspend a chain between two posts. When the chain ...


4

The point on the surface of the Earth where the Sun is currently immediately overhead is called the Zenith Point. Its Latitude and Longitude correspond to the Declination and Greenwich Hour Angle of the Sun. These data points can be approximated to any degree of accuracy and timeframe by a Fourier series of n terms. Accuracy sufficient for sextant work ...


3

The UTM coordinate system, is a kind of Transverse Mercator projection separated in longitude bands and restricted in latitud extent such that the distortions associated with the projection remain small. Also, the UTM coordinate system is conformal projection. Therefore, it preserves the angles. That means that within the UTM zones, a straight line in UTM ...


3

Instead of the Nagy prism formula, I suggest you to use the formula quoted in the following paper: B. Banerjee, S.P. Das Gupta (1977): "Gravitational attraction of a rectangular parallelepiped" Geophysics, vol. 42, n. 5, pp. 1053-1055 doi: 10.1190/1.1440766 I wrote, in Fortran, a TC program based on that formula. If you read the paper you better ...


2

I have recently had to deal with the same problem and tackled it in Matlab, If it helps, here's a link to it on the file exchange https://au.mathworks.com/matlabcentral/fileexchange/57349-nagyprism-x1-x2-y1-y2-h-rho- Here is the code: % A function to perform terrain corrections using the Nagy % prism formula. % To calculate the terrain correction for a ...


2

There are some wonderful answers here, but I think a simplified plain English answer would be helpful. Barring any nearby mountains, and various foibles, the closest point to the sun at the June solstice is where it is midday on the tropic of Cancer. At the December solstice, it is where it is midday on the tropic of Capricorn. At equinox it is where it is ...


2

Whichever spot on the surface of the Earth is experiencing Lahaina Noon, or would be if it wasn't cloudy, is at the subsolar point and pointed directly at the Sun, moreso than any other point on Earth at that moment. Of course, you could get closer to the sun by climbing higher. If you were able to be at the summit of Chimborazo volcano in Ecuador (point ...


2

I did a little poking around and came across a few projects that might be interesting. Based on the work of Peter Bird (2003) there's a github project (fraxen/tectonicplates) that hosts georeferenced data of most major plate boundaries. Seeing as you're interested more in minor plate dynamics, there's another project called GPlates that is an multi-OS open ...


1

It is extremely unlikely to be a sink hole. They are characteristic of waterlogged limestone country such as is found in Florida. Hollows are sometimes found in flows of igneous rock where there has been volcanic activity. Some hollows are large gas bubbles which were trapped when the rock around them solidified, but probably the most common hollows in ...


1

At any one specific moment the subsolar point is the point on Earth that is closest to the Sun at that specific moment. The subsolar point on a planet is the point at which its sun is perceived to be directly overhead (at the zenith);[1] that is, where the sun's rays strike the planet exactly perpendicular to its surface. It can also mean the point ...


1

Hi: Your rocks are not geodes but likely concretions. The wiki article even mentions concretions from Kansas though the concretions described don't to me fit what I see in the images. Better pictures and more description about the rocks would lead to better identification. See Better rock ID requests Wiki's Concretion Page


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