Why Don’t We Fall Off the Earth?

Chloe Effron
Chloe Effron

WHY? is our attempt to answer all the questions every little kid asksHave a question? Send it to why@mentalfloss.com.

Do you know the saying “what goes up, must come down”? There’s a lot of truth to that. No matter how hard you hit that baseball or how high you get on the swings, you’re not going to make it into space (without a spaceship, of course). This is because of something called gravity (GRAV-it-ee). Gravity is the force that keeps you (and all your toys) from floating into space. 

The Earth’s gravity is a force that works kind of like a magnet. When you jump in the air, you come back down because gravity is pulling you towards the center of the Earth. Gravity does a lot more than just keep your feet on the ground. The strong pull of planets has created whole solar systems and galaxies. The Earth's gravity pulls in the Moon, which orbits (or circles) around it. Objects that orbit planets are called satellites (SAT-uh-lights). Some other planets have one or more moons of their own. The largest planet in our solar system, Jupiter, has 63 known moons! The Sun also has a gravitational (grav-uh-TAY-shun-ull) pull. It pulls all the planets in our solar system around it. Just like the Moon circles the Earth, the Earth circles the Sun.   

This force is something that all objects have—even you! The reason you don’t have tiny objects stuck to you is because you’re not big enough to have a strong enough pull. Even really big things like whales aren’t large enough to have a gravitational pull. Only really, really big things like stars, planets, and moons have it. 

The Moon is big enough to have its own pull. Its gravity tugs on the Earth's oceans. That's why we have ocean tides. But the Moon's gravity isn't as strong as the Earth’s. That’s why the astronauts who visited the Moon were able to jump really high. If those same astronauts went to a bigger planet, like Jupiter, the gravity would be a lot stronger. There, they would feel much heavier, and they wouldn't be able to jump much at all. People in spaceships are not near anything with a big gravitational force, so they can float in the air inside the spaceship. 

Alcohol-Producing Gut Bacteria May Harm Livers—Even if You Don't Drink

itakdalee/iStock via Getty Images
itakdalee/iStock via Getty Images

Teetotalers might think their liver is safe from the damaging effects of alcohol consumption, but new research is hinting that even non-drinkers and light drinkers might have cause for concern. It turns out a type of gut bacteria is capable of producing alcohol—and enough of it to potentially cause some pretty serious health consequences, including liver disease.

A study led by Jing Yuan at the Capital Institute of Pediatrics in Beijing, China and published in the journal Cell Metabolism offers details. After evaluating a patient with auto-brewery syndrome (ABS), a rare condition brought on by consumption and fermentation of sugary foods that leaves a person with high blood alcohol levels, researchers made an intriguing discovery. Rather than finding fermenting yeast that may have led to the condition, the patient’s stool contained Klebsiella pneumonia, a common gut bacteria capable of producing alcohol. In this subject, K. pneumonia was producing significantly more alcohol than in healthy patients.

The patient also had nonalcoholic fatty liver disease (NAFLD), characterized by fatty deposits in the liver. While many cases of NAFLD are relatively benign, too much fat can become toxic. Examining 43 other subjects with NAFLD, scientists found that that K. pneumonia was both present and potent, pumping out more alcohol than normal in 60 percent of participants with NAFLD. In the control group, a surplus was found in only 6.25 percent.

To further observe a correlation, scientists fed the bacteria to healthy, germ-free mice, who began to see an increase in fat in their livers after only one month. While not conclusive proof that the bacteria prompts NAFLD, it will likely trigger additional research in humans.

It’s not yet known how K. pneumonia acts in concert with the bacterial profile of the gut or what might make someone carrying stronger strains of the bacteria. Luckily, K. pneumonia can be treated with antibiotics. That’s good news for people who might never touch a drink and still find themselves with a damaged liver.

[h/t Live Science]

5 Hilarious Discoveries from the 2019 Ig Nobel Prize Winners

andriano_cz/iStock via Getty Images
andriano_cz/iStock via Getty Images

Each September, the Ig Nobel Prizes (a play on the word ignoble) are given out to scientists who have wowed the world with their eccentric, imaginative achievements. Though the experiments are usually scientifically sound and the results are sometimes truly illuminating, that doesn’t make them any less hilarious. From postal workers’ scrotal temperatures to cube-shaped poop, here are our top five takeaways from this year’s award-winning studies.

1. Left and right scrota often differ in temperature, whether you’re naked or not.

Roger Mieusset and Bourras Bengoudifa were awarded the anatomy prize for testing the scrotum temperatures in clothed and naked men in various positions. They found that in some postal workers, bus drivers, and other clothed civilians, the left scrotum is warmer than the right, while in some naked civilians, the opposite is true. They suggest that this discrepancy may contribute to asymmetry in the shape and size of male external genitalia.

2. 5-year-old children produce about half a liter of saliva per day.

Shigeru Watanabe and his team nabbed the chemistry prize for tracking the eating and sleeping habits of 15 boys and 15 girls to discover that, regardless of gender, they each produce about 500 milliliters of spit per day. Children have lower salivary flow rates than adults, and they also sleep longer (we produce virtually no saliva when we sleep), so it seems like they may generate much less saliva than adults. However, since children also spend more time eating than adults (when the most saliva is produced), the average daily levels are about even—at least, according to one of Watanabe’s previous studies on adult saliva.

3. Scratching an ankle itch feels even better than scratching other itches.

Ghada A. bin Saif, A.D.P. Papoiu, and their colleagues used cowhage (a plant known to make people itchy) to induce itches on the forearms, ankles, and backs of 18 participants, whom they then asked to rate both the intensity of the itch and the pleasure derived from scratching it. Subjects felt ankle and back itches more intensely than those on their forearms, and they also rated ankle and back scratches higher on the pleasure scale. While pleasure levels dropped off for back and forearm itches as they were scratched, the same wasn’t true for ankle itches—participants still rated pleasurability higher even while the itchy feeling subsided. Perhaps because there’s no peace quite like that of scratching a good itch, the scientists won the Ig Nobel peace prize for their work.

4. Elastic intestines help wombats create their famous cubed poop.

In the final 8 percent of a wombat’s intestine, feces transform from a liquid-like state into a series of small, solid cubes. Patricia Yang, David Hu, and their team inflated the intestines of two dead wombats with long balloons to discover that this formation is caused by the elastic quality of the intestinal wall, which stretches at certain angles to form cubes. For solving the mystery, Yang and Hu took home the physics award for the second time—they also won in 2015 for testing the theory that all mammals can empty their bladders in about 21 seconds.

5. Romanian money grows bacteria better than other money.

Habip Gedik and father-and-son pair Timothy and Andreas Voss earned the economics prize by growing drug-resistant bacteria on the euro, U.S. dollar, Canadian dollar, Croatian luna, Romanian leu, Moroccan dirham, and Indian rupee. The Romanian leu was the only one to yield all three types of bacteria tested—Staphylococcus aureus, Escherichia coli, and Vancomycin-resistant Enterococci. The Croatian luna produced none, and the other banknotes each produced one. The results suggest that the Romanian leu was most susceptible to bacteria growth because it was the only banknote in the experiment made from polymers rather than textile-based fibers.

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