3 proofs that debunk flat-Earth theory

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MICHELLE THALLER: So, Oscar, you asked the question, "What are some of the easiest ways that you can prove that the Earth is round?" Because apparently, this is something that we're debating—I have no idea why.

That's a hard thing for me to even start talking about because there are so many proofs that the Earth is round, it's difficult to know where to start. And it's not okay to think that the Earth is flat. This is not a viable argument.

I have friends who have been on the International Space Station, they have orbited the Earth once every 90 minutes; I've had personal experience with people who have been up in space and can see with their own eyes that the Earth is round. And of course, we've taken all of these amazing pictures from space; they're so beautiful, all those pictures of the Earth.

So I don't really know what's going on right now with this 'Earth is flat' thing, but I will tell you that this is one of the things I really enjoyed teaching my own astronomy class about because there are proofs all around you. It is not difficult to know that the Earth is round. In fact, people have known of this for way more than 2,000 years. The ancient Greeks actually had a number of really elegant, wonderful proofs that the earth was a sphere.

So let's start from the simple to the slightly more complicated. One of the things you can see yourself, with a pair of binoculars, is if you actually go out to a lake and there are boats on that lake, the farther away a boat is the more the bottom of the boat will disappear, and you'll basically just see the mast of the boat. And as a boat goes farther and farther away the last thing you will see is the very top of the mast of that boat, and that's because the boat is actually going over the horizon that's curved—and that means that as it goes farther and farther away you see less and less of the bottom of it, and more of the top of that. You can see that with binoculars by an ocean, by a lake, it's really easy. That wouldn't happen if the Earth were flat—you would simply see the boat getting smaller and smaller and smaller as it went farther away, but you'd be able to see the whole thing with the same proportions.

Now, another way that you can tell that we're on a sphere is to think about how there's something called the tropics on the Earth, and the tropics are places near the equator of the earth were sometimes the sun is overhead in the sky. This was actually something that the Greeks used, not only to prove that the Earth was round about 2000 years ago, but they actually measured the circumference of the Earth, accurate to within just a couple percent. 2,000 years ago we've known that the Earth was round.

There was a really brilliant Greek scientist called Eratosthenes, and Eratosthenes noticed that there was a town called Syene, and on a certain date the sun would actually shine straight down to the bottom of a well. That meant the sun was directly overhead; you could look down a well and see the sun shining back at you.

And on the very same date, farther away in the city of Alexandria, that didn't happen. The sun was not directly overhead, it was a slight angle, and all that Eratosthenes did was he measured the difference in the angle of the sun. It was straight overhead in Syene; in Alexandria it was a little bit less than overhead, and he rationed that that change in angle from one city to another was probably indicative of us being on a curved surface, and you could make all kinds of measurements even between those two cities and see that the angles were different—the sun was at a different place in the sky. Using this, he actually measured the circumference of the Earth, and he got it right 2,000 years ago.

So another really simple proof is that on any given date, at different cities and different places around the world, the sun is at different angles in the sky. That wouldn't happen if the Earth wasn't round.

Then there are some other proofs that are a little more obscure, but they're actually really lovely. One is to observe what happens during a lunar eclipse. Now, a lunar eclipse happens when the Earth casts a shadow on the moon. The moon actually goes dark, in fact, if you've seen one you can actually see the Earth's shadow go across the moon, and when the moon is entirely in the Earth's shadow the moon looks kind of dark and even kind of red-colored; it's really, really beautiful.

What's happening, in that case, is that the sun is on one side of the Earth—the Earth is in the middle—and the Earth is casting a shadow on the moon, and as the shadow moves across the moon you'll notice that the shadow is curved, it's round.

And so something like the sun that's bigger than the Earth and is able to cast a shadow of the Earth on the moon can actually show you the shape of the Earth. "Ah-ha!" you might say, "but could the Earth to be a disk? Could it be flat but it's actually still shaped like a disk, not like a sphere?"

There was a Greek scientist called Aristarchus and what he noticed was that you can get a lunar eclipse at many different angles where the sun is; sometimes the shadow goes straight across the moon, sometimes it just kind of glances the moon—just a little bit is in shadow just on the top or on the bottom. From every different vantage point, every different angle the sun is casting a shadow, you always get a perfectly curved shadow. The only shape that can cast a shadow that's curved from any direction you put the light is a sphere.

So people have known that the Earth is spherical for thousands of years. It's not okay to say that the Earth is flat. This is some sort of strange denial, I don't know where it comes from, and it's something where I keep getting this question. We really need to put this question to bed because we've known the Earth is a sphere for a long time.

There's even some well-meaning people who say, "I don't really believe the Earth is flat, but I'm not really sure what to think about it." And they've asked me some interesting questions, like they've heard that space is a very hot, that when you go up above the atmosphere the temperature of space is millions of degrees, which is true. The problem is there's basically no air at all. So the gas right around the Earth is actually millions of degrees hot. That's actually true, but there's almost none of it, there's almost nothing. Like one single proton whizzes by you at a temperature of a million degrees, it's not the same as temperature in the air, it's not the same thing at all. So that's one that I get sometimes.

And the other one is—I actually said this to somebody, and I couldn't believe they had never thought of it—that with binoculars you can see planets, you can see Saturn and Jupiter, you can see Mars with a telescope, the sun and the moon, everything else you see in the solar system is a sphere. So we're the one thing that is different? And that actually made somebody who was more interested in actually hearing information, that actually got them to think. They were like, "You're right… everything else we take a picture of is a sphere!"

  • Hey flat Earthers, it's time to put your theory to bed once and for all! "There are so many proofs that the Earth is round, it's difficult to know where to start. And it's not okay to think that the Earth is flat; this is not a viable argument," says NASA astronomer Michelle Thaller.
  • Thaller explains three observable proofs that instantly debunk flat-Earth theory with irrefutable evidence of the Earth's round, curvaceous, gloriously spherical shape.
  • The ancient Greeks figured out we were living on a sphere over 2,000 years ago, and there are things you can do to prove that the Earth is indeed round—just go to a body of water and look at ships or boats on the horizon with binoculars. Watch the video for the details!
  • You can follow Michelle Thaller on Twitter at @mlthaller.

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An organism found in dirt may lead to an anxiety vaccine, say scientists

Can dirt help us fight off stress? Groundbreaking new research shows how.

University of Colorado Boulder
Surprising Science
  • New research identifies a bacterium that helps block anxiety.
  • Scientists say this can lead to drugs for first responders and soldiers, preventing PTSD and other mental issues.
  • The finding builds on the hygiene hypothesis, first proposed in 1989.

Are modern societies trying too hard to be clean, at the detriment to public health? Scientists discovered that a microorganism living in dirt can actually be good for us, potentially helping the body to fight off stress. Harnessing its powers can lead to a "stress vaccine".

Researchers at the University of Colorado Boulder found that the fatty 10(Z)-hexadecenoic acid from the soil-residing bacterium Mycobacterium vaccae aids immune cells in blocking pathways that increase inflammation and the ability to combat stress.

The study's senior author and Integrative Physiology Professor Christopher Lowry described this fat as "one of the main ingredients" in the "special sauce" that causes the beneficial effects of the bacterium.

The finding goes hand in hand with the "hygiene hypothesis," initially proposed in 1989 by the British scientist David Strachan. He maintained that our generally sterile modern world prevents children from being exposed to certain microorganisms, resulting in compromised immune systems and greater incidences of asthma and allergies.

Contemporary research fine-tuned the hypothesis, finding that not interacting with so-called "old friends" or helpful microbes in the soil and the environment, rather than the ones that cause illnesses, is what's detrimental. In particular, our mental health could be at stake.

"The idea is that as humans have moved away from farms and an agricultural or hunter-gatherer existence into cities, we have lost contact with organisms that served to regulate our immune system and suppress inappropriate inflammation," explained Lowry. "That has put us at higher risk for inflammatory disease and stress-related psychiatric disorders."

University of Colorado Boulder

Christopher Lowry

This is not the first study on the subject from Lowry, who published previous work showing the connection between being exposed to healthy bacteria and mental health. He found that being raised with animals and dust in a rural environment helps children develop more stress-proof immune systems. Such kids were also likely to be less at risk for mental illnesses than people living in the city without pets.

Lowry's other work also pointed out that the soil-based bacterium Mycobacterium vaccae acts like an antidepressant when injected into rodents. It alters their behavior and has lasting anti-inflammatory effects on the brain, according to the press release from the University of Colorado Boulder. Prolonged inflammation can lead to such stress-related disorders as PTSD.

The new study from Lowry and his team identified why that worked by pinpointing the specific fatty acid responsible. They showed that when the 10(Z)-hexadecenoic acid gets into cells, it works like a lock, attaching itself to the peroxisome proliferator-activated receptor (PPAR). This allows it to block a number of key pathways responsible for inflammation. Pre-treating the cells with the acid (or lipid) made them withstand inflammation better.

Lowry thinks this understanding can lead to creating a "stress vaccine" that can be given to people in high-stress jobs, like first responders or soldiers. The vaccine can prevent the psychological effects of stress.

What's more, this friendly bacterium is not the only potentially helpful organism we can find in soil.

"This is just one strain of one species of one type of bacterium that is found in the soil but there are millions of other strains in soils," said Lowry. "We are just beginning to see the tip of the iceberg in terms of identifying the mechanisms through which they have evolved to keep us healthy. It should inspire awe in all of us."

Check out the study published in the journal Psychopharmacology.