00:03So cool science!
00:11Is it true at noon the equator casts no shadows?
00:15Well, that's a wicked cool question. I got a wicked cool answer that's gonna have you saying,
00:19Whoa, that's so cool. You know, well, unless you're a fart knocker. I mean, a flat earther.
00:25Hi, I'm gonna show you a wicked cool demonstration that's over 2,000 years old,
00:31but it still packs a punch. You know, kind of like a Russian grandmother.
00:39And of course, all you're gonna need is an everyday common index card,
00:43and you can prove the earth is round. You know, stupid people.
00:47People so stupid, they go fishing in the frozen food section.
00:52Get yourself an index card and tape two bent paper clips, one to each side.
00:57And of course, now you're ready to prove that the earth is round.
01:00Check this out.
01:01Okay, so when I move the light over the card when it's flat on the table,
01:04the shadows stay exactly the same.
01:06Okay, so that's not how shadows work here on earth, okay?
01:08So check this out. We're gonna bend the card and place the light directly over one of the paper clips.
01:19Whoa, now check that out. You had a shadow on one side and no shadow on the other.
01:23That's pretty wicked cool. That right there proves that the earth is round right there.
01:27See, 2,000 years ago, they did this exact same thing, and they believed that the earth was round,
01:31and then 2,000 years later, you got people here, they got satellites and all sorts of technology,
01:35and people are like, oh my god, I don't believe it.
01:38So, how does the bent index card prove the earth is round?
01:42And what does this have to do with, well, the equinoxes?
01:46Well, don't look at me. Take a closer look at this.
01:51Since the earth is tilted and goes around the sun,
01:54different amounts of light will reach the earth at different times a year.
01:58Around mid-March and September, the earth's axis is neither tilted towards or away from the sun.
02:03This puts the earth's equator at a 90-degree angle to the sunlight.
02:07So, we call these the equinoxes, or equal night.
02:11This is also why there are no shadows during noon at the equator during the equinoxes.
02:16Eratophenes, an ancient Greek philosopher, noticed that where he lived sticks cast shadows.
02:21While 800 kilometers away, near the equator, there were no shadows at the same time.
02:26He realized that the earth has to be curved.
02:29The shadow he measured was a 50th of a circle.
02:32So, he multiplied 50 by 800 kilometers and got 40,000 kilometers, or the circumference of the earth.
02:38Ships sailing over the horizon didn't fall off the edge.
02:41They gradually disappear, and then they came back.
02:43The earth sometimes casts a shadow on the moon.
02:46That shadow is always round, no matter what.
02:49So, now you know more about No Shadow Day.
02:51You know, being able to prove the earth is round right at home with an index card is why science
02:57doesn't throw you a curveball.
03:00Dr Amenescaz
03:00Dr Lemong
03:01Dr Lemong
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