# Tag Info

Accepted

### What place on Earth is closest to the Sun?

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 ...
• 17.7k

### Is it a coincidence that the circumference of the Earth in kilometers is almost $2^{12}$?

Well, as others have pointed out we're a little off from $2^{12}$ kilometers. However, there is no coincidence that our world's circumference is close to $40000$ kilometers. From Wikipedia: The metre ...
• 3,926

### Is there a name for the great circle where latitude and longitude are equal?

If the Earth was a sphere, then the curve in the last picture of tfb's answer is the curve of Viviani; otherwise, if you make the oblate spheroid assumption, you get a slightly distorted version of ...
• 193

### Is it a coincidence that the circumference of the Earth in kilometers is almost $2^{12}$?

There's something wrong with your math, $2^{12} \ = \ 4096$: $2^x \ = \ 40\ 000$ $\therefore x\log2 \ = \ \log\ 40\ 000$ $\therefore x \ = \ \frac{\log\ 40000}{\log\ 2}$ $\therefore x \ = \ 15.28771$ ...
• 24.7k

### What place on Earth is closest to the Sun?

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 ...
• 109

### If the accuracy of measurement of the earth's volume is not known, how can scientists assert that the earth is not expanding?

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 ...
• 3,486

### Centripetal Force Perfect Ball and Water

In short, weird things happen when you combine things that don't combine in nature: the Earth as a perfect sphere the Earth spinning on an axis Einstein's equivalence principle tells us that ...
• 3,638

### What place on Earth is closest to the Sun?

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 ...
Accepted

### Is the surface of the Indian ocean really 106 meters below sea level?

Is the surface of the Indian ocean really 106 meters below sea level? Obviously not; it is at sea level. It is 100+ meters below the reference ellipsoid. Nor is the spot some hundreds of kilometers ...
• 23.7k

### Centripetal Force Perfect Ball and Water

If the Earth were a perfect ball, which it is not, and had a perfectly smooth and even surface with no basins or irregularities, water would tend to move toward the equator, where it would form a ...
• 4,711

### Great circle in UTM coordinates

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 ...
• 17.7k

### Terrain correction for gravity data using Nagy, 1973

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" ...

### What place on Earth is closest to the Sun?

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 ...
• 300
Accepted

### Plate boundary lon/lat data

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 ...

### Terrain correction for gravity data using Nagy, 1973

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-...
• 31

### What place on Earth is closest to the Sun?

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 ...
• 121
Accepted

### What is the right term to describe the observation that your true bearing changes if you move in a non-cardinal direction on a globe?

I would refer to it as "geodesic curvature", because this is exactly what happens. On a sphere all distinct geodesics curve everywhere towards each other except for perpendicular pairs. That ...
• 3,926
Accepted

### What is the pitch and roll in a tiltmeter sensor?

It's simply the measurement of incline in the x and y horizontal directions: Roll is the angle created by the slope $\frac z y$ Pitch is the angle created by the slope $\frac z x$ A tilt meter and ...

### Is there a way to intuitively explain that the North of Sweden is closer to Australia than the South?

As some comments suggest, nothing substitutes for a globe and a tape measure. But there is a subtle hint of the outcome. Australia is southeast of Sweden according to latitudes and longitudes, but ...
• 3,926
1 vote
Accepted

### How to compute spherical harmonics coefficients using orthogonality?

The equations are mostly correct, but the equation for calculating the gravitational potential on the lunar surface needs to be modified to: V(\varphi,\lambda)=\sum_{\mathrm{n}=2}^\infty\sum_{m=0}^\...
• 21
1 vote

### How to find out if three points on Earth are on the same great circle arc?

I would take the same approach as Jean-Marie Prival, but using a different toolset, because I'm not familiar with GIS in general and have never been in a room that has ever seen Mathematica. But I do ...
1 vote

### What is the right term to describe the observation that your true bearing changes if you move in a non-cardinal direction on a globe?

The only (non NS) path that maintains a fixed bearing relative to true north is a "rhumb line". By contrast, all other straight line paths will see their bearing change relative to north: ...
• 2,813
1 vote

### Possible cavern?

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 ...
• 4,711
1 vote

### What place on Earth is closest to the Sun?

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 ...

Only top scored, non community-wiki answers of a minimum length are eligible