Tag Archives: facts

The crowd can do as good a job spotting fake news as professional fact-checkers — if you group up enough people

New research suggests that relatively small, politically balanced groups of laymen could do a reliable job of fact-checking news for a fraction of today’s cost.

Image credits Gerd Altmann.

A study from MIT researchers reports that crowdsourced fact-checking may not actually be a bad idea. Groups of normal, everyday readers can be virtually as effective as professional fact-checkers, it explains, at assessing the veracity of news from the headline and lead sentences of an article. This approach, the team explains, could help address our current misinformation problem by increasing the number of fact-checkers available to curate content at lower prices than currently possible.

Power to the people

“One problem with fact-checking is that there is just way too much content for professional fact-checkers to be able to cover, especially within a reasonable time frame,” says Jennifer Allen, a Ph.D. student at the MIT Sloan School of Management and co-author of a newly published paper detailing the study.

Let’s face it — we’re all on social media, and we’ve all seen some blatant disinformation out there. That people were throwing likes or retweets at, just to add insult to injury. Calls to have platforms better moderate content have been raised again and again. Steering clear of the question of where exactly moderation ends and manipulation or censoring begins, one practical issue blocking such efforts is sheer work volume. There is a lot of content out in the online world, and more is published every day. By contrast, professional fact-checkers are few and far between, and they don’t enjoy particularly high praise or high pay, so not many people are planning on becoming one.

With that in mind, the authors wanted to determine whether unprofessional fact-checkers could help stymie the flow of bad news. It turns out they can if you lump enough of them together. According to the findings, the accuracy of crowdsourced judgments — from relatively small, politically balanced groups of normal readers — can be virtually as accurate as those from professional fact-checkers.

The study examined over 200 news pieces that Facebook’s algorithms flagged as requiring further scrutiny. They were flagged either due to their content, due to the speed and scale they were being shared at, or for covering topics such as health. The participants, 1,128 U.S. residents, were recruited through Amazon’s Mechanical Turk platform.

“We found it to be encouraging,” says Allen. “The average rating of a crowd of 10 to 15 people correlated as well with the fact-checkers’ judgments as the fact-checkers correlated with each other. This helps with the scalability problem because these raters were regular people without fact-checking training, and they just read the headlines and lead sentences without spending the time to do any research.”

Participants were shown the headline and lead sentence of 20 news stories and were asked to rate them over seven dimensions: how “accurate,” “true,” “reliable,” “trustworthy,” “objective,” and “unbiased” they were, and how much they “describ[ed] an event that actually happened”. These were pooled together to generate an overall score for each category.

These scores were then compared to the verdicts of three professional fact-checkers, who evaluated all 207 stories involved in the study after researching each. Although the ratings these three produced were highly correlated with each other, they didn’t see eye to eye on everything — which, according to the team, is par for the course when studying fact-checking. More to the point, these fact-checkers agreed on the verdict about individual stories 49% of the stories. Two of the three agreed on a verdict with the third disagreeing on 42%, and all three disagreed on a verdict on 9% of the stories.

When the regular reader participants were sorted into groups with equal numbers of Democrats and Republicans, the average ratings were highly correlated with those of the professional fact-checkers. When these balanced groups were expanded to include between 12 and 20 participants, their ratings were as strongly correlated with those of the fact-checkers as the fact-checkers’ were with each other. In essence, these groups matched the performance of the fact-checkers, the authors explain. Participants were asked to undertake a political knowledge test and a test of their tendency to think analytically

Overall, the ratings of people who were better informed about civic issues and engaged in more analytical thinking were more closely aligned with the fact-checkers.

Judging from these findings, the authors explain, crowdsourcing could allow for fact-checking to be deployed on a wide scale for cheap. They estimate that the cost of having news verified in this way rounds up to roughly $0.90 per story. This doesn’t mean that the system is ready to implement, or that it could fix the issue completely by itself. Mechanisms have to be set in place to ensure that such a system can’t be tampered with by partisans, for example.

“We haven’t yet tested this in an environment where anyone can opt in,” Allen notes. “Platforms shouldn’t necessarily expect that other crowdsourcing strategies would produce equally positive results.”

“Most people don’t care about politics and care enough to try to influence things,” says David Rand, a professor at MIT Sloan and senior co-author of the study. “But the concern is that if you let people rate any content they want, then the only people doing it will be the ones who want to game the system. Still, to me, a bigger concern than being swamped by zealots is the problem that no one would do it. It is a classic public goods problem: Society at large benefits from people identifying misinformation, but why should users bother to invest the time and effort to give ratings?”

The paper “Scaling up fact-checking using the wisdom of crowds” has been published in the journal Science Advances.

We create ‘fake news’ when facts don’t match our biases

If you also dislike fake news, you should probably find a mirror and put on a stern look. A new study found that people unconsciously twist information on controversial topics to better fit wide-held beliefs.

Image credits Roland Schwerdhöfer.

In one study, people were shown figures that the number of Mexican immigrants has been declining for a few years now — which is true, but runs contrary to what the general public believes — and tended to remember the exact opposite when asked later on. Furthermore, such denaturations of facts tended to get progressively worse as people passed the (wrong) information along.

Don’t believe everything you think

“People can self-generate their own misinformation. It doesn’t all come from external sources,” said Jason Coronel, lead author of the study and assistant professor of communication at Ohio State University.

“They may not be doing it purposely, but their own biases can lead them astray. And the problem becomes larger when they share their self-generated misinformation with others.”

The team conducted two studies for their research. In the first one, they had 110 participants read short descriptions of four societal issues that could be quantified numerically. General consensus on these issues were established with pre-tests. Data for two of them fit in with the broad societal view on these issues: for example, many people generally expect more Americans to be in support of same-sex marriage than against it, and public opinion polls seem to indicate that this is true.

However, the team also used two topics where the facts don’t match up to the public’s perception. For example, the number of Mexican immigrants to the U.S. fell from 12.8 million to 11.7 between 2007 and 2014, but most people in the U.S. believe the number kept growing.

Image credits Pew Research Center.

After reading the descriptions, the participants were asked to write down the numbers given (they weren’t informed of this step at the beginning of the test). For the first two issues (those consistent with public perception), the participants kept the relationship true, even if they didn’t remember the exact numbers. For example, they wrote a larger number for the percentage of people supporting same-sex marriage than for those that oppose it.

For the other two topics, however, they flipped the relationship around to make the facts align to their “probable biases” (i.e. popular perception on the issue). The team used eye-tracking technology to track participants’ attention when reading the descriptions.

“We had instances where participants got the numbers exactly correct—11.7 and 12.8—but they would flip them around,” Coronel said. “They weren’t guessing—they got the numbers right. But their biases were leading them to misremember the direction they were going.”

“We could tell when participants got to numbers that didn’t fit their expectations. Their eyes went back and forth between the numbers, as if they were asking ‘what’s going on.’ They generally didn’t do that when the numbers confirmed their expectations,” Coronel said.

For the second study, participants were asked to take part in a telephone (the game) process. The first person in a telephone chain would see the accurate statistics about the number of Mexican immigrants living in the United States. They then had to write those numbers down from memory and pass them along to the second person in the chain, and so on. The team reports that the first person tended to flip the numbers, stating that Mexican immigrants increased by 900,000 from 2007 to 2014 (they actually decreased by about 1.1 million). By the end of the chain, the average participant had said the number of Mexican immigrants increased in those 7 years by about 4.6 million.

“These memory errors tended to get bigger and bigger as they were transmitted between people,” said Matthew Sweitzer, a doctoral student in communication at Ohio State and co-author of the study.

Coronel said the study did have limitations. It’s possible that the participants would have better remembered the numbers if the team explained why they didn’t match their expectations. Furthermore, they didn’t measure each participant’s biases going into the tests. Finally, the telephone game study did not capture important features of real-life conversations that may have limited the spread of misinformation. However, it does showcase the mechanisms in our own minds that can spread misinformation.

“We need to realize that internal sources of misinformation can possibly be as significant as or more significant than external sources,” said Shannon Poulsen, also a doctoral student in communication at Ohio State and co-author of the study. “We live with our biases all day, but we only come into contact with false information occasionally.”

The paper “Investigating the generation and spread of numerical misinformation: A combined eye movement monitoring and social transmission approach” has been published in the journal Human Communication Research.

DNA length

17 Quick Science Facts that Will Blow Your Mind

Why don’t more people appreciate science? Personally, I believe it has something to do with science communication and the way we teach science in our schools.

With this in mind, here are a couple amazing scientific facts that I hope will inspire you to learn something new every day — they’ve certainly done so for me. However, this list is much too short; keep it growing by adding your own science facts in the comments section.

1. There is enough DNA in the average person’s body to stretch from the sun to Pluto and back — 17 times

DNA length

The human genome (the genetic code in each human cell) contains 23 DNA molecules (called chromosomes), each containing from 500,000 to 2.5 million nucleotide pairs. DNA molecules of this size are 1.7 to 8.5 cm long when uncoiled — about 5 cm on average. There are about 37 trillion cells in the human body, so if you were to uncoil all of the DNA encased in each cell and place the molecules end to end, it would sum to a total length of 2×1014 meters — enough for 17 Pluto round-trips (the distance from the sun to Pluto and then back again is 1.2×1013 meters). As an added bonus, you should know that we each share 99% of our DNA with every other human — just to show that we’re far more alike than different.

2. The average human body carries ten times more bacterial cells than human cells

bacteria human body

It’s funny how we compulsively wash our hands, spray our countertops, or make a grimace when someone sneezes near us, when, in fact, each and every one of us is a walking petri dish! All the bacteria living inside you could fill a half-gallon jug — there are 10 times more bacterial cells in your body than human cells, according to Carolyn Bohach, a microbiologist at the University of Idaho. Don’t worry, though: most of these bacteria are helpful. In fact, we couldn’t survive without them.

For example, bacteria produce chemicals that help us harness energy and nutrients from our food. Germ-free rodents have to consume nearly a third more calories than normal rodents to maintain their body weight, and when the same animals were later given a dose of bacteria, their body fat levels spiked despite the fact that they didn’t eat any more than they had before. Gut bacteria is also very important for maintaining immunity. (image source).

3. It takes a photon up to 40,000 years to travel from the core of the sun to its surface, but only 8 minutes to travel the rest of the way to Earth

A photon travels, on average, a particular distance before being briefly absorbed and released by an atom, which scatters it in a new random direction. To travel from the sun’s core to the sun’s surface (696,000 kilometers) so it can escape into space, a photon needs to make a huge number of drunken jumps.

The calculation is a little tricky, but the conclusion is that a photon takes many thousands and many millions of years to drunkenly wander to the surface of the Sun. In a way, some of the light that reaches us today is energy produced millions of years ago. Amazing!

4. At over 2,000 kilometers long, The Great Barrier Reef is the largest living structure on Earth

Coral reefs consist of huge numbers of individual coral polyps (soft-bodied, invertebrate animals) that are linked together by tissue. The Great Barrier Reef is an interlinked system of about 3,000 reefs and 900 coral islands divided by narrow passages, located just beneath the surface of the Coral Sea. Spanning more than 2,000 km and covering an area of some 350,000 sq km, it is the largest living structure on Earth and the only one visible from space. However, this fragile coral colony is beginning to crumble, battered by the effects of climate change, pollution, and manmade disasters.

5. There are 8 times as many atoms in a teaspoonful of water as there are teaspoonfuls of water in the Atlantic ocean

A teaspoon of water (about 5 mL) contains 2×1023 water molecules, but each water molecule is comprised of 3 atoms: two hydrogen atoms and one of oxygen. Moreover, if you’d laid down end to end each water molecule from a teaspoon down end to end, you’d end up with a length of 50 billion km — 10 times the width of our solar system.

6. In an entire lifetime, the average person walks the equivalent of five times around the world

The average moderately active person takes around 7,500 step/day.  If you maintain that daily average and live until 80 years of age, you’ll have walked about 216,262,500 steps in your lifetime. Doing the math;  the average person with the average stride living until 80 will walk a distance of around 110,000 miles — which is the equivalent of walking about 5 times around the Earth, right on the equator.

7. There are actually over two dozen states of matter (that we know of)

Everybody knows that there at least three states of matter: solid, liquid, and gas. If you’re a little bit more versed in physics, you also know about the fourth fundamental state of matter called plasma —  a hot ionized gas, with prime examples including lightning or neon signs. But beyond these common states of matter, scientists have discovered a myriad of exotic states of matter that occur under special conditions. One of them is the Bose-Einstein condensate, where atoms chilled to only 0.000001 degrees above absolute zero start behaving like waves, rather than particles as they ought to on the macroscopic scale. Essentially, the atoms behave like one super atom, acting in unison.

Another interesting exotic state of matter is represented by time crystals — regular, boringly ordered crystals with a twist: A fourth dimension, time, is added so that the material exhibits different periodic structures over time. What makes these crystals particularly remarkable has less to do with the fact that they repeat in time but rather more with the fact that they’re intrinsically out of equilibrium. Because time crystals are never able to settle down, say into a diamond or ruby, there’s a lot we can learn from them.

8. Killer whales are actually dolphins

Despite their name, killer whales or orcas are the largest members of the dolphin family. Technically, orcas are also whales because delphinids belong to the Cetacean order within the toothed whale (Odontoceti) suborder. However, the term whale is typically reserved for baleen whales of the Mysticeti suborder.

The major physical feature that ensures orcas are dolphins is the presence of a melon — a fatty deposit that assists the animals in echolocation and only exists in dolphins.

Orcas are highly intelligent, highly adaptable and able to communicate and coordinate hunting tactics. They are extremely fast swimmers and have been recorded at speeds of up to 54kph! A wild orca pod can cover over 160 kilometers a day, foraging, and socializing.

9. Grasshoppers have ears in their bellies

Unlike humans, grasshoppers do not have ears on the side of their heads. Like the ears of people, the grasshopper sound detector is a thin membrane called a tympanum, or “eardrum”. In adults, the tympanum is covered and protected by the wings, and allows the grasshopper to hear the songs of its fellow grasshoppers.

The grasshopper tympanum is adapted to vibrate in response to signals that are important to the grasshopper. Male grasshoppers use sounds to call for mates and to claim territory. Females can hear the sound that males make and judge the relative size of the male from the pitch of the call (large males make deeper sounds). Other males can hear the sounds and judge the size of a potential rival. Males use this information to avoid fights with larger male grasshoppers or to chase smaller rivals from their territory.

10. You can’t taste food without saliva

In order for food to have taste, chemicals from the food must first dissolve in saliva. It’s only once they’ve been dissolved in a liquid that the chemicals can be detected by receptors on taste buds. During this process, some salivary constituents chemically interact with taste substances. For example, salivary buffers (e.g., bicarbonate ions) decrease the concentration of free hydrogen ions (sour taste), and there are some salivary proteins that may bind with bitter taste substances.

Here’s a quick science experiment to test this out — get out a clean towel, and rub your tongue dry; then place some dry foods on your tongue, one by one, such as a cookie, pretzel, or some other dry food. After this session, drink a glass of water and repeat. Did you feel a difference?

11. When Helium is cooled to almost absolute zero (-460°F or -273°C, the lowest temperature possible), it becomes a liquid with surprising properties: it flows against gravity and will start running up and over the lip of a glass container!

superfluid helium

We all know helium as a gas for blowing up balloons and making people talk like chipmunks, but what most people don’t know is that it comes in two distinct liquid states — one of which is borderline creepy. When helium is just a few degrees below its boiling point of –452°F (–269°C), it can suddenly do things that other fluids can’t, like dribble through molecule-thin cracks, climb up and over the sides of a dish, and remain motionless when its container is spun. No longer a mere liquid, the helium has become a superfluid — a liquid that flows without friction.

“If you set [down] a cup with a liquid circulating around and you come back 10 minutes later, of course, it’s stopped moving,” says John Beamish, an experimental physicist at the University of Alberta in Edmonton.

This happens because atoms in the liquid will collide with one another and slow down.

“But if you did that with helium at low temperature and came back a million years later,” he says, “it would still be moving”.

12. If Betelgeuse exploded, transitioning from the red supergiant stage to supernova, it would light our sky continuously for two months. It could happen anytime — within a couple of thousand years, tomorrow or even now

supernova explosion

Betelgeuse lies some 430 light-years from Earth, yet it’s already one of the brightest stars in Earth’s sky. The reason is that Betelgeuse is a supergiant star — the largest type of star in the Universe. Betelgeuse has a luminosity about 10,000 times greater than that of the Sun and its radius is calculated to be about 370 times that of the sun. If it were positioned at the center of our sun, its radius would extend out past the orbit of Mars. Because it’s near the end of its lifetime, Betelgeuse is likely to explode into a supernova.

13. Octopuses have three hearts, nine brains, and blue blood

Two of the hearts work exclusively to move blood beyond the animal’s gills, while the third keeps circulation flowing for the organs. When the octopus swims, the organ heart stops beating, which explains why these creatures prefer to crawl rather than swim (it exhausts them).

An octopus also has nine brains — well, sort of. There’s one ‘main’ brain where all the analysis and decision making takes place and eight ancillary brains — one at the base of each arm — that function as preprocessors for all the information obtained by that arm. Two-thirds of an octopus’ neurons reside in its arms, which can independently figure out how to open a shellfish, for instance, while the main brain is busy doing something else.

Our blood is red due to the fact that it contains iron-based hemoglobin to transport oxygen to cells. Octopuses, on the other hand, use the copper-based cyanoglobin, which performs the same function, albeit less efficiently — this makes octopuses have less stamina than you might expect.

14. An individual blood cell takes about 60 seconds to make a complete circuit of the body

You have about 5 liters of blood in your body (at least, most people do) and the average heart pumps about 70 mL of blood out with each beat. A healthy heart also beats around 70 times a minute. So, if you multiply the amount of blood that the heart can pump by the number of beats in a minute, you actually get about 4.9 liters of blood pumped per minute, which is almost your whole body’s worth of blood. In just a minute, the heart pumps the entire blood volume around your body.

15. The known universe is made up of 50,000,000,000 galaxies.

There are between 100,000,000,000 and 1,000,000,000,000 stars in a normal galaxy. In the Milky Way alone there might be as many 100 billion Earth-like planets. Still think we’re alone?


16. Hot water freezes faster than cold water

In certain conditions, hot water can freezes faster than cold water — a counter-intuitive phenomenon known as the Mpemba effect. There is a number of proposed explanations for the Mpemba effect, including faster evaporation of hot water that reduces the volume left to freeze, the formation of a frost layer on cold water that insulates it, or different concentrations of solutes such as CO2. The phenomenon is named after schoolboy Erasto Mpemba from Tanzania, who in the 1960s claimed in his science class that ice cream would freeze faster if it was heated first before being put in the freezer.

17. About 1% of our genes come from plants, fungi, and other germs

According to research from the University of Cambridge, humans have evolved with genes acquired from plants and fungi. But how did they get there? Rather than a straightforward single branching tree where genes are inherited from parents, scientists argue that sometimes foreign genes may spread by a process known as horizontal gene transfer. For instance, different species of bacteria often exchange genes via viruses.


3 facts about water that prove it doesn’t play by the rules

Image via pexels.

Should you ever have to put out a fire, would you risk dousing it with a chemical formed from two of the most vehemently combustible elements in the periodic table, or just go with plain tap water?

That was a trick question — water is exactly one such substance. Oxygen and hydrogen, by themselves, are some of the most reactive elements we know of and thank goodness for that — because of its huge energy potential, hydrogen is our best bet for future fuels, and oxygen is so despairingly fire-prone that even our cells use it for energy. Air is about 21% oxygen, but increase that concentration by a few percent and even flame-retardant foam will burn like a grease fire. This ability to combine with any fuel has allowed it to power complex organisms for as long as there have been complex organisms.

Yet put the two together and they become a firefighter’s best friend. Which is surprising, to say the least. Like that one colleague who missed the department-wide memo, water goes about its day seemingly innocent of how the laws of physics and chemistry say it should behave. Chemists bundle these unexpected traits under the term “anomalous properties of water,” and today we’re going to go through a few of the peculiar things this liquid does.

First of all, it shouldn’t even be liquid at room temperature

Image credits Joe Pell/Flickr.

Water is the typical go-to example for what liquids are, yet chemically speaking, it should be a gas. Water has a molar mass of roughly 18 g/mol and is liquid at room temperature, but hydrogen sulfide (with a similar structure) and ammonia (with a similar molar mass,) are gases over the same thermal range even though they are just as heavy, if not heavier, than water. Even air, with a mass of roughly 29 g/mol is heavier than water but is decidedly gaseous.

This happens because water molecules really like hanging with other water molecules. The H-O-H structure of water means that they become highly polarized, the hydrogen atoms forming positive poles and the oxygen atom forming a negative pole. When left to their own devices, water molecules will line up poles of opposing charges and bunch into each other, forming what are known as hydrogen bonds. To get an idea of their effect, however, we have to look at both the molar mass and densities of these substances.

Molar mass basically tells us how much an identical number of molecules of each substance weighs. Density tells us how much a set volume of a substance weighs, so we can get an idea of how many molecules are in a given space. This way, we can see how powerful an effect the hydrogen bond has on keeping water molecules together — while ammonia has a density of 0.73 kg/m³ and hydrogen sulfide has a density of 1.36 kg/m³, water has a whopping density of 1,000 kg/m³. The molecules are just incredibly close packed, reducing free space between them and turning a should-be gas into the liquid we know and love.

The high cohesion of its molecules also gives water a high freezing and melting point, allowing it to form all the oceans and seas we know and love.

It’s less dense as a solid than as a liquid

Image via pixabay

As a substance goes from a gas to a liquid and then a solid its molecules progressively get smushed into each other — that’s why in solids, the same quantity of matter takes less space than in a liquid, which takes up even less space than a gas. But water won’t have any of that. If you’ve ever seen a picture of an iceberg you’ll know that ice, the solid form of water, is less dense than — and thus, floats on — its liquid state.

The same hydrogen molecules come into play here. Water’s freezing point is at 0 degrees Celsius (32 Fahrenheit.) But it reaches its highest density at 4 degrees Celsius (39.2 Fahrenheit,) after which the molecules start drifting apart as it freezes. While in a liquid state each molecule is tied to approximately 3.4 other molecules via hydrogen bonds, when water freezes it crystallizes into a rigid lattice tying each molecule with 4 others. This arrangement is more rigid but less space efficient, forming gaps (free space) that increase its volume and effectively lower the overall density of ice.

This property has ruined many a water pipe during winter but does wonders for life. Think of the ice cover on a lake frozen over. If water behaved according to the rule book and ice was denser than the liquid, lakes would freeze over from the bottom up. This would not only make ice-skating way less enjoyable but would kill off all the animals and plants that lived in it. The way it is now, water at 4 degrees Celsius sinks to the bottom and the coldest water rises up to the surface. So fish can live in a comfortable (for them) environment, and get a free layer of ice that insulates the lake from cold in the same bargain. Seeing as life on Earth most likely evolved in the oceans, we should all be very grateful for this.

It expands dramatically when turned into a gas

Image credits Wikimedia user BrockenInaglory

As we’ve seen, water has a low molar weight but forms a surprisingly dense liquid. This also means that it has a very high liquid-to-gas volume change, increasing its volume 1603.6 fold — the highest known, in fact, with the exception of metals and almost double that of typical gases (oxygen increases just 804 fold.)

When water is heated, thermal energy pushes its molecules apart, counteracting the effect of its hydrogen bonds. This is why power plants boil water for their turbines and not alcohol, for example, even if it has a higher boiling point. This very large increase in volume on vaporization allows fine water mists to be used in fighting fires by displacing the oxygen with water vapor.

Under the surface

Water is nothing if not spectacular. There’s much more to be said about it, how it covers much of the planet, shapes continents, underlies all life on Earth and keeps the planet from getting too hot, among other things — this article barely touches the tip of the iceberg, so to speak. But for me, the fact that even a substance as commonplace and innocuous as water has so much going on under the surface, that we’d never expect just by looking at it, is nothing short of amazing.

Volcano facts and other pieces of hot science

Volcanoes are some of the most amazing geological features but quite often, they’re misunderstood or not understood at all. Here we’ll get to know them a bit better, starting with the basic facts and the moving onto cool and surprising facts, and of course, continuing with everyone’s favorite (from a distance): eruptions.

Basic Volcano Facts

1. Volcanoes are ruptures in the Earth’s crust. Our planet’s crust is split into 17 major tectonic plates, and almost all volcanoes occur at the edges between these plates.

2. There are three types of volcanoes: stratovolcano (conical volcano consisting of layers of solid lava), cinder cone volcano (steep hill of tephra that accumulates around the vent) and shield volcano (built entirely or almost entirely from fluid lava vents).

3. Volcanoes can be active (with eruptions in the past 10,000 years), dormant (no eruptions in the past 10,000 years, but could wake up) and extinct (unlikely to ever erupt again). However, active volcanoes can become dormant and extinct, and dormant volcanoes can wake up. Before 79 AD, Vesuvius was considered dormant and its eruption was catastrophic. Knowing whether a volcano is truly extinct is hard to determine.

4. We’re still not sure how many volcanoes there are in the world, but geologists identified about 1300 active volcanoes, not counting underwater volcanoes.

5. The biggest volcano on Earth is Hawaii’s Mauna Kea. At 33,500 feet (10,210 meters) it’s even taller than the Everest, but most of it is underwater, so its height relative to sea level is lower. However…

6. The tallest volcano in the solar system is on Mars. Olympus Mons on Mars is a shield volcano with a height of nearly 22 km (16 mi), almost three times higher than Mount Everest. It was able to grow this big because Mars doesn’t have active tectonic plates.

Volcanic eruption on Io. Image credits: NASA/JPL.

7. Earth isn’t the most active place in the solar system – Jupiter’s moon Io is the most volcanic body in the solar system. Astronomers recently witnessed two huge eruptions, possibly largest than any ever recorded on our planet.

8. The two most active volcanoes in the world are Etna in Italy and Hawaii’s Kilauea, depending on how you judge. Etna has been active in the past 3,500 years, but it’s still being used for agriculture because its slopes are so fertile. Kilauea has been in a state of constant eruption since 1993, and more than 90% of its surface is made from young lava.

Image via USGS.

9. Volcanoes can be scary, but supervolcanoes can be downright terrifying. St. Helens, one of the largest eruptions in history spewed up 0.25 cubic kilometers of volcanic material while the last known eruption from the Yellowstone caldera ejected 4000 times more – 1000 cubic kilometers.

Volcano Eruption Facts

10. There are three types of volcanic eruptions: magmatic eruptions (involving gas decompressions that propel the eruption forward), phreatic eruptions (superheating of steam via contact with magma, often with no ejected material) and phreatomagmatic eruptions (compression of gas within magma, the complete opposite of magmatic eruptions).

11. How dangerous are volcano eruptions? In 1815, the volcano Tambora exploded in Indonesia. All vegetation on the island was destroyed and projected into the sea. Uprooted trees mixed with pumice ash, washed into the sea and formed rafts up to 5 km (3.1 mi) across. The eruption sent material into the stratosphere, at an altitude of more than 43 km (27 mi). Over 10,000 people were killed directly by the eruption, but that was only the beginning.

The epic explosion of Mount Tambora in 1815 left a massive crater behind, 3.7 miles wide and 3,600 feet deep. (NASA)

Over 40,000 people were killed by hunger and disease in neighboring islands, and the effects were felt globally. The following year, 1816 was called “the year without a summer”, as snow fell in the summer in Boston and New York. Crops were destroyed, widespread famine was reported in Asia, Europe and the Americas. It’s impossible to estimate the total damage, but up to 100,000 people lost their lives following this eruption. A Massachusetts historian summed up the disaster: “Severe frosts occurred every month; June 7th and 8th snow fell, and it was so cold that crops were cut down, even freezing the roots.” Which leads us to another question:

12. What if a supervolcano erupts? Geologically, it won’t mean much for the planet. At a geological scale, supervolcanoes erupt all the time… but for humans, the effects would be ghastly. The tens or hundreds of thousands of lives lost will pale in comparison to what will happen. The world will be thrown into a nuclear-type winter, where food availability could become a luxury (because volcanic eruptions can block sunlight, lowering global temperatures). Famine and widespread disease will emerge for at least a couple of years, as no country has the food reserves to last that long; it’s extremely difficult to gauge the full impact such an eruption might have. However, you shouldn’t waste much sleep on this – it’s extremely unlikely for such an eruption to take place in the next few thousand of years.

13. The last known supervolcano eruption was the Toba eruption 74,000 years ago, when more than 2,500 cubic kilometers of magma were erupted. The largest eruption in recent human history was the 1815 eruption described above.

Chichester Canal circa 1828 by J. M. W. Turner. Image via Wikipedia.

14. But it’s not all bad. Volcanic eruptions make sunsets more vibrant. The eruptions spew hundreds, thousands or even millions of tons of dust and gaseous sulfur dioxide into the stratosphere. The finer dust particles remain in the atmosphere, sometimes for years, producing vivid sunsets and twilight effects.

In fact, a team of German and Greek researchers are studying paintings of sunsets after historical eruptions to discover clues about our atmosphere, and even study global warming.

Image via Wikipedia.


15. Some volcanic eruptions can create massive thunderstorms and we still don’t know exactly why. A study published in Science found that this phenomenon, also called dirty thunderstorms, appear because electrical charges are generated when rock fragments, ash, and ice particles in a volcanic plume collide and produce static charges, just as ice particles collide in regular thunderstorms.

More Volcano Facts

16. You need at least 3.35 kg of lava to boil a liter of water. Quora user Nissim Raj Angdembay calculated that for a lava of an average temperature of 950 °C, you need to use 3.35 kg of lava to boil a liter of water. Of course, this is only a theoretical calculation, and in practice, you’d need a bit more as some of the heat will be lost to the ambient.

17. There is one unique volcano, Ol Doinyo Lengai, that produces black carbonatic lava. It also isn’t as hot as other types of lava and it’s much less viscous – comparable to water.

Black carbonatic lava. Image via SwissEduc

18. The volcanic rock pumice is the only rock that can float in water. Pumice is an extrusive volcanic rock with a very high content of water and gases extruded quickly out of a volcano. The unusual foamy configuration makes it very light.

19. Volcanic energy can be harvested to warm water and even generate electric energy. Geothermal energy generates about 3% of renewable energy-based electricity.

20. The Maleo bird in the Indonesian island of Sulawesi uses volcanic heating to incubate its eggs.

21. When Paricutin in Mexico erupted from 1943-1952 (more on that a bit later), not a single person was killed by lava, rocks or flows, but three people were killed by lightning.

Paricutin. Image via Wikipedia.


22. Lava temperature varies between 700 to 1,200 °C (1,292 to 2,192 °F). Geologists do sometimes use a thermometer called a “thermocouple” to take a volcano’s temperature.

23. Lava chemistry greatly influences both the temperature and the type of eruption. Lava with greater silica content (more basic) tends to be hotter, more fluid, and erupt more “gently” – think of the Hawaiian lava flows. Lava with less silica (acidic) tends to have more explosive eruptions. They also form different types of rocks.

24. In 1943, a Mexican farmer named Dionisio Pulido started to notice something strange in his cornfield. It started as a slight depression, and soon started to fissure, eliminating volcanic material. By 1952, the volcano was already 424 meters high and damaged a 233 square km area with the ejection of stone, ash and lava. Three people were killed by lightning as described above. Today, Paricutin the volcano is 2,800 m (9,200 ft) high and is considered dormant.