Earth Is A Sphere. Few Proofs For The Flat Earth Society With Members All Around The Globe ?

Earth taken 5 mins ago.
Captured by NASA's GOES-16 satellite
14 jan 2023

 

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TO SEE WHAT EARTH REALLY LOOKS LIKE ???

VIDEO

View: https://youtu.be/xzZPzmMtQA8

 

Over 2000 years ago, the mathematician Eratosthenes had heard that in Syene,
a city south of Alexandria, it cast no vertical shadows at noon on the summer solstice.

The sun was right overhead.

He wondered if this was also true in Alexandria.

So, on 21 June, he nailed a stick directly to the ground and waited to see if a shadow was cast at noon.

He noticed that there was a shadow.

Now, if the sun's rays arrive at the same angle at the same time of day and a stick in Alexandria casts a shadow,
while a stick in Syene does not, it means that the earth's surface is curved.

At that point, all that remained for Eratosthenes was to do some calculations to discover the circumference of the Earth.

Since the difference of the shadow is 7 degrees in Alexandria and Syene,
this meant that 7 degrees separated the two cities on the surface
compared to the Earth's 360 degrees.

Legend has it that Eratosthenes hired a man to travel the distance between the two cities, and
discovered that they were separated by 5000 stadia (800 km),
but it is likely that he was already aware of the distance thanks to the caravan journeys.

He then used simple proportions to find the circumference of the Earth:
7.2 degrees is 1\50 of 360 degrees, so 800 times 50 equals 40,000 km.

And so, he found the circumference of the Earth using a stick and his brain

 

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At what altitude can you see the curvature of the Earth?

Posted byM. Özgür NevresOctober 9, 2020
At what altitude can you start seeing the curvature of the Earth? Can you see it, for example, on top of a skyscraper? Or atop a mountain? Or from a passenger plane? From a high-altitude balloon? From space only?

Most people don’t realize how large the earth is compared to the height of a mountain or the altitude of a passenger aircraft. It’s easy to think we’re really high up when we are atop a high mountain or in a passenger plane, but comparatively, even in the case of the plane (planes fly higher even the highest mountain on Earth – Mount Everest, commercial aircraft typically fly between 31,000 and 38,000 feet – about 5.9 to 7.2 miles – high), we’re just skimming the surface of our planet. So, how high do you have to be to see the curvature of the Earth?


What do you mean by the “curvature of Earth”?

Technically, you can see the curvature of Earth even at sea level. Even the ancient Greeks knew that the Earth is round: a ship on the horizon moving toward the viewer will gradually appear with the masts first, followed by the superstructure, then the hull.

The top of the Boston skyline is just barely visible from Cape Cod, because of the curvature of the Earth.

This image of Thorntonbank Wind Farm (near the Belgian coast) with the lower parts of the more distant towers increasingly hidden by the horizon, demonstrates the curvature of the Earth. By Lieven – Own work, CC BY-SA 4.0, Link
From just 3 meters (10 feet) above the surface, you can see the horizon 6.2 km (3.85 mi) apart. If you’re 30 meters (100 feet) high, you’ll be able to see up to 20 km (12.5 mi) away. This is one of the reasons ancient civilizations understood that the Earth was curved, not flat, at least from the sixth century BC.
So, the real question here is: “at what altitude can you start seeing the curvature of your horizon“.
Spoiler: you have to be a lot higher than that flat-earther ‘Mad’ Mike Hughes who died while trying to reach an altitude of 5,000 feet (1,525 meters) while riding his steam-powered rocket to “prove” the Earth is flat. He could climb a mountain to reach a higher altitude than launching himself onboard his homemade stupid “rocket”. He still wouldn’t see the curvature of Earth (actually curvature of the horizon), though, but that would prove nothing. Earth is big.

How high do you have to be to see the curvature of the Earth?

Related: How did Eratosthenes calculate the Earth’s circumference more than 2,000 years ago?
The curvature of the Earth: at what altitude can you start seeing it?

There’s actually a study answering this question titled “Visually discerning the curvature of the Earth” and here’s the abstract of the study:
“Reports and photographs claiming that visual observers can detect the curvature of the Earth from high mountains or high-flying commercial aircraft are investigated. Visual daytime observations show that the minimum altitude at which curvature of the horizon can be detected is at or slightly below 35,000 feet (10,600 meters – about the cruising altitude of a passenger aircraft), providing that the field of view is wide (60 degrees) and nearly cloud-free.”
Scott Manley also created a video about this.

How high do you have to be to see the curvature of the Earth? Video by Scott Manley.
Manley says: “It’s well understood that from the surface of the Earth the curvature of the planet is not readily visible, but, as you travel higher the shape of the world becomes apparent to a casual glance.”
“So I wanted to actually quantify this in a visual form using YouTube’s 360° Video feature, it’s obviously best experienced through a VR headset or a ‘Cardboard’ style viewer, but you can also use the web browser if you just want to appreciate the visuals.”
Sources and further readings

• “How high must one be for the curvature of the earth to be visible to the eye?” on Stack Exchange
• At what altitude do you see the curvature of the Earth? on Quora
• Study: “Visually discerning the curvature of the Earth” on Research Gate