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Why Do Elephants Have Big Ears?

When humans are hot, we sweat. Elephants, however, cannot sweat like we do. So how do they regulate their body temperature?

Elephants are huge, which means they produce a lot of body heat. Since elephants also typically live in very hot climates, it's essential that they have a very efficient way to get rid of their extra body heat. Luckily, elephants come with a built-in solution: big, floppy ears.

On the inside of an elephant's ears, you will find a web of tiny blood vessels. The skin of the ear is very thin, and the blood vessels are very close to the surface. When the temperature of the elephant's blood is greater than the temperature of his surroundings, heat is released from the ears.

The same thing happens when you hold an ice cube in the palm of your hand. Heat flows from an area of high heat to an area of low heat. While you may be tempted to say, “This ice cube is making my hand cold," in reality, the heat from your hand is actually making the ice cube warmer.

Heat-releasing blood vessels aren't the only useful function of an elephant's ears. They also act like giant fans. As elephants flap their ears back and forth, they create a light breeze that can speed up the cooling process. It is a bit like stepping out of a cool shower and standing in front of a fan. An elephant's ears can cool its body by up to 5° Celcius (that's 9° Farenheit)!

An African elephant's ears can grow to be six feet long and four feet wide. Asian elephants tend to live in shady forests and don't have to endure the same extreme temperatures as their African cousins. As a result, Asian elephants have smaller ears than African elephants.

On hot days, you may even see elephants rolling around in mud, taking a dip in a pond, or using their trunks like hoses to spray down their bodies. The heat then leaves their bodies by flowing into the cooler mud or water.

Who Invented the High Five?

Have you ever scored a hat trick on the soccer field? Have you done well on a big test at school? If so, you might have celebrated by raising your hand high in the air toward a friend or teammate. As they do the same and you slap hands together, you both join in the celebration.

That’s right! We’re talking about the high five. It may seem like the high five has been around forever. But the Oxford English Dictionary has only included the term as a noun since 1980. It was added as a verb in 1981.

The name “high five” comes from the fact that you’re raising five fingers (your hand) up in the air (high). But exactly how did this time-honored way of celebrating get started? As it turns out, there are several different versions of how the high five started. The two most likely sources of the high five come from the sports of baseball and basketball.

For years, many people have believed that the first high five took place on October 2, 1977. That day, it happened in Dodger Stadium between Glenn Burke and Dusty Baker of the Los Angeles Dodgers. Dusty Baker hit an important home run. He made the Dodgers the first team in baseball history to have four players with at least 30 home runs each.

It was a magical sports moment. It boded well for the Dodgers, who were heading into the playoffs. The next batter was Glenn Burke. He headed to home plate to congratulate Baker. Burke raised his hand in the air toward Baker, who returned the gesture. They smacked hands. According to Baker, “[h]is hand was up in the air, and he was arching way back. So I reached up and hit his hand. It seemed like the thing to do.” And the rest, as they say, was history . . .

Or was it? There’s another version of high five history. It credits the invention of the hand gesture to Louisville Cardinals basketball players Wiley Brown and Derek Smith during the 1978-79 season. According to the players, Brown went to give a regular low five to teammate Smith during a practice session.

The low five had been a hand gesture popular among Black Americans since at least World War II. Instead of returning the low five, Smith looked Brown in the eye and said, “No. Up high.” Brown understood what Smith was getting at.

That year’s Louisville Cardinals players were known as the Doctors of Dunk. They liked to play above the rim and slam dunk the ball. Brown thought, why stay low when we play so high? So they raised their hands and the high five was supposedly born.

Both stories are well-documented. But there are many other claims of high fives occurring in other sports even earlier. More than likely, the gesture developed simultaneously in different sports in different areas until it gained popularity.

One thing’s for certain, though. The high five is a part of popular culture that is not likely to go away anytime soon. So the next time you want to celebrate an achievement with a friend, just yell “High five!” and stick your hand in the air!

How Do Fireflies Glow?

In the summer, have you seen lights in the night sky? We’re not talking about stars, or even the Northern Lights. Instead, we’re talking about fireflies.

Fireflies are sometimes called lightning bugs. They are known for their glow power, but they’re not alone. There are also deep-water fish and even bacteria that produce their own light. The fancy word for this is “bioluminescence.”

Fireflies never need to worry about changing a light bulb or paying the electric bill. Their light source comes from inside! A chemical change makes each blip of light. The reaction occurs between a protein called luciferase, a pigment called luciferin, and oxygen. When they combine, the firefly glows!

Most bioluminescent creatures glow all the time, like a light bulb with no off switch. What makes fireflies unique is how they turn their lights on and off. Researchers believe fireflies turn on their lights by sending signals from their brains to special light organs in their abdomens. Their abdomen is where the light-producing chemical reaction takes place.

So why do fireflies spend so much time flipping the lights on and off? Fireflies are born knowing how to glow as larvae. Some people call them “glow worms.”

Science believes bioluminescence serves a different purpose for larvae than it does for adult fireflies. The larvae contain chemicals that are yucky or even toxic to other creatures. As little worms, the light is more of a warning that alerts anything on the hunt for a snack that they should stay away.

For adult fireflies, science believes bioluminescence serves two purposes: to find a mate and to lure prey. Lightning bug blips happen in the blink of an eye. While we can’t tell the difference, female lightning bugs know what they’re looking for.

Research has found that female lightning bugs prefer “flashy” males. Some females prefer to mate with males that have the longest flash, while others prefer males that flash the fastest.

Scientists study the lightning bug’s glow-power. They have found ways to use luciferase. By putting this light-making gene into the cells of other animals, they can watch what happens.

This is an exciting discovery for the world of medicine. With more research, we might be able to make cancer cells glow so researchers can easily track and kill them.

Forensic science also uses luciferase. Investigators sometimes use a weak solution that has this firefly enzyme. When used at a crime scene, it can reveal tiny bits of blood the human eye might not see. That means fireflies can help solve a mystery!

Why Are They Called Deadlines?

When it comes to homework assignments or work projects, there's one thing that many people dread: deadlines. Why do we have them? And why are they called deadlines? That sounds so ominous, doesn't it?

Deadlines are time limits that are set so that a particular task or goal is completed or achieved no later than a certain point in time. They have many purposes and, even if we don't like them sometimes, they are important.

Try to imagine what school would be like if there were no deadlines associated with homework. Homework is often given to help you master things you've learned about in class. If you didn't do your homework on a timely basis, it would be nearly impossible for your teacher to move your entire class forward to build upon what you've already learned.

The same holds true at work. If you have a job to do, it's usually because someone is depending upon you to complete a task. If your job is to change the oil in a car, the people who own the cars need that job done in a reasonable time frame, so that their car will run smoothly and they can get where they need to be.

The term “deadline" has uncertain origins. The earliest uses of the word appear to have referred simply to lines that did not move. This usage may have developed into “deadline" being used around the time of the Civil War as a term related to prisons, meaning a line that could not be crossed by prisoners.

Eventually, the term began to be used by journalists in the sense we know today. This was most likely the result of the design of early printing presses that featured a guideline on the printing plate. Any text inside the line would be printed. Any text outside the line — the “deadline" — would not be printed and would “die."

So, today, if you miss your deadline for homework, it's not accepted or graded. Homework submitted on time will be accepted and graded. Your ultimate grade may depend upon whether you do your homework and keep it “alive" or miss the deadline and let it “die"!

How Long Can Your Fingernails Grow?

Ever had an itch in the middle of your back that you couldn't quite reach? If only your fingernails were a little longer, you might think. So just how long could they grow?

Believe it or not, you can grow your fingernails to be really, really long. How long? According to the Guinness World Records website, the current world record holder for longest fingernails is Christine “The Dutchess" Walton from Las Vegas, Nevada.

The nails on her left hand measure a whopping 10 feet 2 inches, and the nails on her right-hand measure 9 feet 7 inches. That's a total of 19 feet 9 inches worth of fingernails. Wow!

How did she grow them that long? Would you believe that she hasn't cut her nails since 1990? It's true!

Of course, you might not want nails that long. Although holding a world record would be cool, fingernails that long might make it a bit difficult to do some of the things you enjoy doing every day.

Plus, it would take a lot of time and patience to grow them that long. Fingernails grow very slowly. On average, fingernails only grow about one-tenth of an inch every month. For example, if you lost most of a fingernail, it could take six months or more for it to grow back completely.

Fingernails do come in handy, though. Not only do they protect the soft tips of your fingers, but they also help you do many things, such as scratch your itchy back and open aluminum cans.

Nails are made of keratin. Keratin is the same protein that makes up your hair and the upper layer of your skin. Nails start at the nail root, which is just underneath the cuticle (the spot where your nail meets the skin). The cuticle helps protect new nails as they grow.

As your body makes nail cells, they push out from the nail root and move along the nail bed. That's the flat part under your nails. Under the nail bed are lots of tiny blood vessels that feed your nails and give them their pink color.

How Hot Is the Center of the Earth?

Have you ever dug a hole in the ground? Maybe you’ve planted a flower, buried secret treasure, or dug sand on a beach. People dig into Earth's surface every day for many reasons. But have you ever WONDERed just how far down the ground goes?

It’s nearly four thousand miles from the Earth’s surface to its true center. To get there, you’d have to dig through the planet’s four layers. These include the crust, mantle, outer core, and inner core.

Of these layers, only one has ever been seen with the naked eye: the crust. Like the crust on top of a pie or loaf of bread, this layer makes up the outermost part of the Earth. It contains solid rocks and minerals, including materials like coal and precious metals.

How thick is the planet’s crust? It varies. Beneath the oceans, this layer may be as thin as 3.1 miles (5 kilometers). Under land, though, it ranges from 18.6 to 43.5 miles (30-70 km) thick. Regardless, humans have never drilled deep enough into the Earth to break through its crust. The farthest people have ever drilled is 7.6 miles (12 km).

Below the crust lies the largest of Earth’s layers, called the mantle. This layer spans 1,865 miles (3,000 km) and is semi-solid. It is mostly made up of iron, magnesium, and silicon. The mantle is also where diamonds are made. Experts believe melted rock makes up the uppermost part of this layer. This allows Earth’s tectonic plates to move along it.

Finally, below the mantle lies the Earth’s core. It contains two sections: the outer and inner core. The outer core is about 1,398 miles (2,250 km) thick. It is liquid and made mostly of iron and nickel. This layer influences Earth’s magnetic field through electrical currents.

The inner core is solid and incredibly dense. Like the outer core, it contains iron and nickel. At the center of the Earth, the inner core is also extremely hot. It reaches temperatures of 9,800 °F (5,400 °C). Today, experts also believe there may be another layer—called the inner inner core. Scientists are still learning about this part of the Earth.

Are you WONDERing how experts learn about the Earth’s layers? They do so using seismic waves caused by earthquakes. By studying how these waves travel through the Earth, scientists can learn about each of the planet’s layers.

Today, experts also monitor the size and shape of the Earth’s inner core. Why? Because it’s growing! Of course, this happens at a slow rate. However, the core grows by a tiny amount each year.

By studying the inner core, scientists have also found that it’s not a perfect sphere—it’s lopsided. That’s because the inner core is growing faster on its eastern side than on its western end. Experts believe this pattern of growth has played a role in the formation of Earth’s magnetic field.

Have you ever dreamed of digging a tunnel to the other side of the Earth? If so, you now know that’s a much deeper hole than you may have imagined! The Earth's layers have formed over millions of years, and people are still learning about them today. What else would you like to learn about the ground beneath our feet?

What Caused the Tunguska Event?

Have you ever watched a meteor shower? How about a solar eclipse? Maybe you’ve seen a comet soar overhead. Stare up at the sky long enough, and you’ll certainly see some pretty cool stuff!

Sometimes, though, science has difficulty explaining things people see in the sky. If you’ve been WONDERing with us for a while, you may already know about UFOs. Today’s Wonder of the Day is about another mystery—the Tunguska Event.

On June 30, 1908, strange reports poured in from Siberia. People felt a sudden, intense heat and heard loud bangs coming from near the Tunguska River. One person described seeing “the sky split in two.” People saw flames streak through the air above the forest’s trees.

Even 40 miles away, people were knocked to the ground by wind and heat. Forests were flattened; over 80 million trees were knocked to the ground. As far away as eastern Asia, the night sky glowed with sunlight reflected from dense cloud cover. The event killed many animals, including reindeer, and up to three people are believed to have died.

Today, this incident is known as the Tunguska Event. It’s also known as the Tunguska Explosion or Tunguska Impact. What caused it? Experts have worked to answer that question for decades.

Just after the event, some people pointed to aliens. They thought the heat and flames could have been caused by a spaceship from another planet. Locals even wondered if it was the work of an angry god. Due to the harsh Siberian conditions, it was years before a team of scientists could investigate the area.

In 1927, Leonid Kulik led a team to the site. Kulik worked in the St. Petersburg Museum’s meteorite collection as a curator. When they arrived, they found that trees at the center of the event were standing upright. However, they were stripped of all limbs and bark. Nearly two decades later, trees in Hiroshima, Japan, were left in the same condition after the city was hit by an atomic bomb.

Kulik’s team believed that a rock from space—like an asteroid or a comet—caused the Tunguska Event. However, it left no crater behind. To explain this, the team concluded that the rock must have exploded in the Earth’s atmosphere.

This was the leading explanation for nearly a hundred years. In 2020, though, experts gave an update. Scientists at the Siberian Federal University now believe an asteroid passed through the atmosphere instead of exploding. To do so, the rock must have been around 650 feet wide.

If these experts are right, the Earth had a very close encounter. The asteroid would have looked like a fireball in the sky as it streaked above the Siberian forest. Had it reached the ground, it would have made a crater around two miles wide.

Imagine you witnessed the Tunguska Event. How would you have explained it? Would you have thought it was a UFO? A comet? Event scientists are still trying to solve the case today!