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• Earth LOOKS flat. It FEELS flat. The logical explanation is: the earth is flat! Right?

• #facepalm. But like, once you get past the crazytalkHow do we know the Earth IS round?

• Welcome back my woke friends, Trace here for DNews. If you follow the pervasive yellow

• journalism online and elsewhere, you've probably heard of Rapper B.o.B.'s beef with NASA, science

• and specifically Dr. Neil deGrasse Tyson, astrophysicist and science celeb. In short,

• some pop culture peeps think the Earth is Flat. Proving them wrong is simple, though

• it took hundreds of years for science to figure it out in the first place.

• how do we know otherwise? We know the Earth is round by observing it

• closely. If you watch a ship as it disappears over the horizon, the bottom vanishes first

• and then the top disappears later. It looks like it's sinking. That's because the Earth

• is curved. Using a stopwatch you can do your own experiment to prove it. Watch the sun

• set over the ocean or a open plain with a friend. If you stand, while they lay down,

• each will see the sun cross the horizon at a slightly different time!

• how did we first realize the earth was round? The Greeks first realized this 2500 years

• ago, and spent hundreds of years attempting to explain it. First, mathematician Pythagoras

• looked at the moon and discovered a curve in the line dividing light from shadow on

• its surface -- called the terminator. A flat moon would have a straight line! The only

• explanation? The moon must be a sphere! Sometime later, Anaxagoras, while watching the moon

• during an eclipse, realized the shadow covering the moon must be from the Earth! As that shadow

• is definitely curved, the Earth must be round! And still later in about 350 BC, Aristotle

• noted that star constellations, visible in Greece were hidden beyond the horizon in Egypt.

• His conclusion, yet again, was the Earth must be a sphere, just like the moon! Sidebar:

• Notice, humanity knew the Earth was round 1800 years before 1492 when Columbus Sailed

• the Ocean Blue. Just debunking some grade school crap.

• how curved is the earth? Once these great thinkers realized the Earth

• was curved, they wanted to PROVE IT. A Greek astronomer named Eratosthenes figured it out.

• On the summer solstice, the sun reaches a peak at the top of the sky. Eratosthenes went

• to two distant locations in Egypt on the Solstice and measured the angles cast by the shadows

• in each place. Then, using some geometry he could calculate the curvature of the Earth

• between those places! From there, he could extrapolate how many degrees around the circle

• of the Earth he had moved -- ultimately, revealing the circumference and diameter of the EARTH!!

• Dang.

• Thanks to all these ancient humans we know Earth is just a bit over 40 thousand km around

• the poles (about 24,860 miles) (which is supported by modern observations), and knowing that

• we can determine how far the horizon is from you -- which changes depending on how high

• above sea level you are. The Earth is curved, and we know it.

• Why do these people think this? In the end, the problem is Flat Earthers just

• don't trust science. When the Flat Earth Society was founded in the mid-1920s, the idea was

• observation trumps all. This is called the Zetetic philosophy. Many skeptics believe

• the same. If the Earth looks flat it must be flat. Often they cry "Prove me wrong!"

• "Only trust your own observations!" The funny thing about that argument is that it was observation

• that showed us the Earth’s curvature in the first place! Pythagoras observed that

• shadow line across the moon. Countless people have observed ships sailing underneath the

• horizon. NOT TO MENTION the fact that weve gone to space and observed a very spherical

• Earth from above.

• And if you don’t believe all those people for some reason, make your own observation.

• Climb a mountain, watch a ship sail away, or watch the sun set with a friend. And behold

• an inarguably spherical Earth.

• Conspiracy theories are just, the best, aren't they? Have you ever wondered why people love

• 9/11 conspiracies? Why are we so obsessed with the Illuminati or which conspiracy theories

• might be actually true? TestTube Plus is the podcast/show for you! We cover

• Do y'all know anyone that we should make a video debunking? Comments. Do it.

Earth LOOKS flat. It FEELS flat. The logical explanation is: the earth is flat! Right?

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B1 earth flat moon curved horizon shadow

# How We Know The Earth Isn’t Flat

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陳美妤 posted on 2016/01/30
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