55 votes
Accepted

Does gravity increase the closer to the core you get?

The below figure, taken from Wikipedia shows a model of the free fall acceleration, i.e., 'gravity'. The left-most point corresponds to the center of the Earth; then further right at $6.3\cdot1000$ km ...
Erik's user avatar
  • 1,979
43 votes
Accepted

How high must one be for the curvature of the earth to be visible to the eye?

Depends on your eye. You can realise the curvature of the Earth by just going to the beach. Last summer I was on a scientific cruise in the Mediterranean. I took two pictures of a distant boat, within ...
DrGC's user avatar
  • 1,713
35 votes

Comparing the Earth with a basketball?

The picture above is an image of the Earth without water. We know that the picture above is a very exaggerated one. About the image The image shown in the question is very widely claimed to show an ...
David Hammen's user avatar
23 votes

How high must one be for the curvature of the earth to be visible to the eye?

A quick Google turned up a published article answering precisely this question (Lynch, 2008). The abstract states: Reports and photographs claiming that visual observers can detect the curvature of ...
Pont's user avatar
  • 5,411
21 votes

How to quickly or easily prove the world is spherical?

I'm sorry that this answer will be unsatisfactory and, strictly spoken, off topic, but I want to give it anyway. The answer is: You can't. Don't waste your time. Your relative has developed a paranoia....
Peter - Reinstate Monica's user avatar
20 votes
Accepted

How to quickly or easily prove the world is spherical?

To answer my own question based on the useful comments here, my favorite methods were: The earth's shadow cast on the moon during an eclipse. It is easy to observe and the flat earth counter argument ...
dutch's user avatar
  • 421
17 votes
Accepted

What are we seeing when we see the curvature of Earth?

the horizon is a circle centered at the viewer's position There are two things wrong with this. The first is the assumption that the Earth is entirely spherical - there are no hills, mountains or ...
Semidiurnal Simon's user avatar
16 votes
Accepted

Why wouldn't the earth be "always daytime" if the "daily cycle of sunlight" was drawn full-scale?

The sun is really far away. Thus its rays are essentially parallel at the earth's orbit. So, while the diagram you posted is clearly a bit off in terms of the relative size and distance between the ...
Matt Hall's user avatar
  • 11k
15 votes
Accepted

Can I see curvature of the Earth on a picture

Make your own numbers... I will take one sample, just change your figures. I have one 4K resolution dron camera. So I can register 3840 x 2160 pixels in one shot. Considering the Earth as an ...
David García Bodego's user avatar
15 votes

How can one know the correct direction on a cloudy day?

The book Finding Your Way Without Map or Compass by Harold Gatty (Goodreads review) is well worth a read if you're interested in this sort of thing. The chapters Reflections in the Sky and Directions ...
Chris H's user avatar
  • 251
14 votes

Effects of CERN on earth's magnetic field?

CERN is a scientific site developed to create anti matter The scientific activity at CERN involves many things, anti matter being just one of them. For more information you can read their anti matter ...
Gimelist's user avatar
  • 23k
12 votes

How to quickly or easily prove the world is spherical?

Skype. Skype someone at least 10 time zones away. Ask them to point the camera at the sky. Proven. This actually works really well for a psychological reason as well. Its easy to deny abstract ...
George Mauer's user avatar
12 votes
Accepted

What is this narrow band of clouds?

Given the weather patterns, it looks like Google Earth is generating those cloud overlays from some recent (i.e., the current day) satellite images. That line is suspiciously close to the edge of ...
Deditos's user avatar
  • 3,920
12 votes
Accepted

Why does this shoreline change this way?

Short version; the beach moves because the waves change. Long version; Beaches, and in fact entire bays, conform in shape and alignment to the prevailing wave patterns in the area. The exact magnitude ...
Ash's user avatar
  • 4,260
11 votes

Why wouldn't the earth be "always daytime" if the "daily cycle of sunlight" was drawn full-scale?

The sun is about 100 times the size of the Earth (in diameter), and the distance from the sun to Earth is about 100 times the diameter of the sun. Below is an image showing the sun, Earth, and the ...
Eubie Drew's user avatar
  • 1,207
10 votes
Accepted

Volcano in ocean?

From a list & map of known seamounts and submarine volcanoes it is unlikely the orange region in your picture is a submarine volcano. The average depth of the Pacific Ocean is 4280 m. At such a ...
Fred's user avatar
  • 24.1k
10 votes

Effects of CERN on earth's magnetic field?

In addition to @Michael's excellent answer, keep in mind that fields from charges drop off with the inverse of the distance squared and from dipoles (like those of the Earth and a lot of CERN's larger ...
Graipher's user avatar
  • 331
10 votes
Accepted

How is global greenhouse gas emission calculated?

Your question is simple enough, but the answer depends on what exactly you're looking for. Who is emitting where right now? Real-time global monitoring of greenhouse gas emissions with a high ...
gerrit's user avatar
  • 11.6k
9 votes

How to quickly or easily prove the world is spherical?

Just after sunset, call a friend some number of time zones to the west and ask them where the sun is in their sky. Or, just before sunrise, call a friend some number of time zone to the east and ask ...
Daniel Griscom's user avatar
9 votes

At what latitudes does daytime last exactly 24 hours once in the year?

The latitudes today are 66°33′46.1″ N and S, the Arctic and Antarctic Circles. By definition, north of the Arctic circle, and south of the Antarctic circle, everywhere gets at least one day with no ...
Matt Hall's user avatar
  • 11k
9 votes

What are these Gizmos at Izaña Atmospheric Research Center in Spain?

Those are Sun/Moon multispectral photometers and ski radiometers. These are instruments that can scan the sky or track the Sun/Moon for direct measurements. They measure light intensity at multiple ...
Camilo Rada's user avatar
  • 17.6k
9 votes

How is global greenhouse gas emission calculated?

I can imagine a satellite observation-based model that calculates emissions on a spatial basis but I am not sure if our technology is advanced enough to do that accurately. It is. The first ...
Jean-Marie Prival's user avatar
8 votes

How high must one be for the curvature of the earth to be visible to the eye?

Further to DrGC's excellent answer, a subjective assessment of visibility of the Earth's curvature can be gleaned from pilot's experioence over many decades. These can be summarized as: Commercial ...
Gordon Stanger's user avatar
8 votes

What time and date is the sun directly overhead a given place on Earth?

Having the sun directly overhead can happen only between the Cancer and Capricorn tropics. That is, only the places between 23.5° of latitude north and 23.5° of latitude south. On the Cancer tropic (...
Camilo Rada's user avatar
  • 17.6k
8 votes
Accepted

Why does Earth's atmosphere have a whiter color near the horizon?

The reason is that the horizon is paler is that we are seeing all wavelengths of sunlight equally scattered into our eye from along the line-of-sight to (and beyond) the horizon, so the horizon ...
David Bailey's user avatar
7 votes

Why wouldn't the earth be "always daytime" if the "daily cycle of sunlight" was drawn full-scale?

But if you scale up the Sun to it's real size compared to the Earth, Is pretty big. But then to be realistic in that manner you would also have to scale up the distance from the earth to the sun. ...
Jon Hanna's user avatar
  • 171
7 votes
Accepted

How to locally identify a cold front passage?

A cold front lies in a trough of low pressure and separates air masses. As you mention in your question there are differences in temperature and the winds on either side of the front, though these ...
casey's user avatar
  • 14.1k

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