Universe

Both bows are shaped the same way, but instead of being a beautiful arc made up of different colors, a moonbow has only one shade. It is a silvery white, the color of moonlight. There are only two places on earth where you can see a moonbow. One is the Zambezi River in South Africa, … Read more

Many people have described the sound of a tornado high in the air as similar to the “Buzzing of a Million Bees”. Still others describe it as a screaming, hissing sound. When a tornado is approaching, however, the sound changes, and many describe it as a giant blow torch or 1,000 trains rushing through a … Read more

Most people who get caught in a tornado aren’t so lucky. Some strange “miracles” do occur, however. On April 9, 1947, a man living near Higgins, Texas, opened his front door and was lifted out of his house by a tornado’s wind. He went sailing over treetops for 200 feet, then, very gently, landed on … Read more

It isn’t very big, and few people know about it, but there is a real desert in Maine. It is called the Desert of Maine and is located south of the town of Freeport. In 1779, the Tuttle family had a 300-acre potato farm on the site. The farm was also home to a small … Read more

In the rain forests of Sumatra, an Indonesian island, grows a very strange plant called the rafflesia. This plant has no stem and no leaves, but consists of just a single flower. And that flower is the biggest in the world, often measuring over three feet across. A full-grown rafflesia weighs 15 pounds, and can … Read more

Rhubarb is a vegetable that is often baked in a pie and used as a dessert. The plant consists of large leaves, up to two feet across in some cases, on long, thick stalks. The stalks may be an inch in diameter and up to two feet long. But the stalk is really part of … Read more

You may have seen the small, moss-like plants called lichens covering rocks or the branches of old trees. Though you’d never guess it from looking at these plants, lichens are really two plants in one: a fungus and an alga. The fungus and alga in a lichen live so closely together that you’d need a … Read more

The green, brown, and red seaweed you find washed up on the beach or floating in the water are kinds of plants called algae. These plants have green chlorophyll, just as ordinary green leaves do, and can make their own food from sunlight and nutrients in the soil or water. But algae are as different … Read more

Can you imagine a cactus taller than a five-story building? The saguaro, a slow-growing cactus found in the American Southwest and in Mexico, can grow higher than some oak trees. One saguaro in Arizona stands 52 feet tall, while another in Mexico is over 58 feet tall, and weighs about 20,000 pounds!

In general, cactus plants are the slowest growing plants on earth. One kind of cactus, the saguaro, grows just one inch in the first ten years of its life. The saguaro cactus doesn’t grow a branch until it’s 16 years old, and after that, it grows just an inch a year. But some pine trees … Read more

A slime mold may sound like a disease or an infection, but it’s actually a very odd plant. It’s so odd, in fact, that scientists once thought the slime mold was an animal. Because, like an animal, a slime mold can crawl! A slime mold begins its life as a group of small cells that … Read more

Can you imagine a tree as tall as a seven-story building? Sure, some trees in your neighborhood may be that tall. But can you imagine a single leaf that big? The raffia palm is a tree that grows in the tropics of South America and Indian Ocean islands. While the average size of most palm … Read more

A tiny fungus that scientists call Zoophagus insidians has a most unusual way of catching the microscopic animals that form its diet. This fungus, which lives in the water, has short branches, called hyphae, along its main stem. When tiny water animals, called rotifers, bite into these hyphae, the rotifers swell up inside the fungus’s … Read more

The term “carrot-topped” is often used for a person with reddish hair, but not all carrots are orange-red. There are white carrots, yellow carrots, and pale green carrots. And if you were to look at some Dutch paintings from the 16th century, you’d find purple carrots too, because that’s what carrots looked like at the … Read more

The Seychelles coconut, found only in the Seychelles Islands near Africa, produces the largest seeds in the plant kingdom. The fruit of this palm tree looks like two coconuts joined together, the reason for its other name, the “double coconut.” Because the coconut contains just one seed, scientists consider the entire fruit to be the … Read more

Birthworts are a family of shrubs and vines with about 600 members. One kind of European birthwort has the habit of “kidnapping” insects that visit its flowers in search of nectar. The “ransom” that the plant seeks is bits of birthwort pollen on the insect’s body. The birthwort’s flower forms a long curved tube, in … Read more

Almost all plants move their leaves and stems in some way, but usually this movement is so slow that we can’t see it. However, this is not true for a common plant called the mimosa. Normally, the long, thin leaves of this plant extend straight out from the stem, and the stem is erect. But … Read more

If you were to see a banana plantation, you’d probably say “yes,” bananas do grow on trees. But although banana plants certainly look like trees, growing up to 30 feet tall, they’re really giant shoots, the banana plant is an herb, not a tree! In fact, the banana is the largest plant on earth without … Read more

Seeds aren’t really alive, but they do have the power to become living things. No one knows for sure how long a seed can exist without being planted before it loses its power to grow into a plant. But it could be almost forever. A seed found in China and proven to be 1,400 years … Read more

The krubi, a plant found in the jungles of Indonesia, is remarkable for two reasons. First, it’s the fastest-growing plant on earth; and second, it forms the biggest group of flowers in the plant kingdom. The krubi looks something like an overgrown tulip, with a long spike growing upward out of its center. But the … Read more

If you think a tree can have only one trunk, and that all trees grow from the ground up, then you’ve never seen a banyan tree. The seeds of this tree, also known as the Indian fig tree, are dropped by birds into the branches of other trees, where they take root. Soon the new … Read more

It’s hard for a plant to grow inside a cave, where there is little fresh air and no direct sunlight. But some plants do thrive inside caves, and one even makes its own light! This plant is a moss that grows on the walls of some caves in Europe. The small, thin branches that make … Read more

The elephant tree of Mexico borrows a page from the defensive system of the skunk. Just as the skunk discharges a scented spray when danger threatens, the elephant tree sends out a spray of foul-smelling oil when it’s attacked by an animal. The elephant tree got its name because its trunk and branches look like … Read more

One of the major differences between an animal and a plant is that an animal can move from place to place, while a plant is rooted to the spot where it grows. But there are some plants that can actually move from place to place in search of water! The resurrection plant, a desert plant … Read more

That depends on what you call “pretty.” Certainly, flowers don’t smell pretty to themselves; their aroma is intended only to attract insects that can help pollinate the plant. Insects, too, probably don’t find that a flower smells “pretty”; they simply visit the flower for its nectar. One flower whose aroma is definitely not pretty is … Read more

The biggest living thing on earth isn’t the whale, it’s a tree! The California Big Trees are a kind of sequoia tree growing in Sequoia National Park in California. Some of these giants grow to a height of 270 feet. The redwood trees are taller, sometimes reaching heights over 350 feet, but the Big Trees … Read more

During storms at sea, sailors have often seen balls of glowing light hovering over the tip of their ship’s masts. Other people have seen the same glow at the end of church spires, at the tops of trees, or at the tips of airplane wings. Sailors believed the glow was a sign that St. Elmo, … Read more

Heat, light, radio waves, and x-rays are all forms of energy. The difference between the various forms of energy depends on the wavelength of the energy waves. Radio waves, for instance, have a very long wavelength, while x-rays have a very short wavelength. We can see only a very small portion of the energy waves … Read more

A light-year may appear to be a measure of time, but it’s actually a measure of distance. A light-year is the distance that light would travel during the course of one earth year. Light travels at the speed of about 186,282 miles per second! And there are a little more than 31.5 million seconds in … Read more

The word fiord, sometimes spelled fjord, comes from Norway, where fiords are common. A fiord is a narrow inlet or arm of the sea that runs far inland, and is bordered by high, steep cliffs that reach far below the surface of the water. Most fiords are more than a half-mile deep. The world’s longest … Read more

A shoreline seems to mark the point where a land mass ends and the ocean floor begins. But that isn’t exactly so. Every land mass includes a shelf of land that extends out into the ocean, sloping downward. This shelf of submerged land is called the continental shelf. Along the East Coast of the United … Read more

The lines that divide the world’s time zones meet at the North and South Poles, so the zones get narrower as they near’ the poles. An Alaskan airline offers a flight over the Arctic regions that includes a circular flight around the North Pole. If you were to circle the North Pole, you’d pass through … Read more

Since ancient times, though the day has been divided into 24 hours, each hour has not always had 60 minutes, as we measure them. The ancient Greeks divided the daytime into 12 hours, but they measured a day from sunrise to sunset. So, the longer a day was, the longer was each hour in it. … Read more

The Greek Eratosthenes, who lived around 250 B.C., was the first man we know of to figure out the size of the earth. Yet he never traveled around the earth, nor did he have any of today’s measuring equipment. How, then, did he do it? Eratosthenes used Euclid’s principles of geometry to solve the problem. … Read more

E = mc2 is a formula that shows, in mathematical terms, the relationship between energy and mass. In this formula, E is energy, m is mass, and c is the speed of light. The number 2 to the upper right of the c means that c is squared, or multiplied by itself. This formula, first … Read more

Every gallon of sea water contains an average of four ounces of salt. And there’s enough salt in the world’s oceans to cover the entire surface of the earth with a layer of salt more than 147 feet thick! But scientists aren’t quite sure how all that salt got into the oceans. Rocks that contain … Read more

Millions of years ago, when much of the earth was a swampy forest, billions of plants and animals died and fell into the shallow water. The oxygen, hydrogen, nitrogen, and carbon in these living things were acted upon by bacteria and pressure over thousands of years, freeing gases from the decayed matter and leaving behind … Read more

In cold weather, low temperatures cause the body to lose heat. But the wind also takes heat from the body, so a temperature reading doesn’t always tell us how cold it really feels. The wind chill factor was devised by weathermen to show how the temperature and the wind combine to produce the feeling of … Read more

You’ve seen quicksilver many times without knowing it. The thermometer you use to take your temperature contains a drop of quicksilver, for quicksilver is just another name for mercury! The quick in quicksilver came from an old word that meant “living.” In earlier times, mercury was called “living silver,” because of the odd way it … Read more

The moon gives off no light of its own, but merely reflects the sunlight that reaches it. So only half of the moon can be lit up by the sun at any one time. We on earth can see only that portion of the moon that is lit by the sun. Sometimes the moon, sun, … Read more

The word “archipelago” comes from two Greek words: archos, meaning “chief,” and pelagos, meaning “sea.” The Greeks originally used the word archipelagos for the Aegean Sea, which washes against the shores of Greece and was their “chief sea.” Since the Aegean Sea is studded with many islands, the word “archipelago” came to mean any sea … Read more

The famous Cliffs of Dover, which lie along the shore of England beside the English Channel, are as white as chalk, as they’re made out of basically the same material as a piece of blackboard chalk! Chalk consists of the remains of tiny sea organisms and fragments of sea shells. These fragments are continually washed … Read more

Greenland, the largest island in the world, is just about the most ungreen place on earth! Most of this island, which is more than three times as large as Texas, is continually covered with ice and snow. This ice sheet is two miles thick in some places. There are no forests in Greenland, but there … Read more

About 70 percent of our planet is covered with water. Including all seas and oceans, water covers about 140 million square miles of earth, with an average depth of 11,600 feet. That means that the total amount of water on earth is 315 million cubic miles! If all the water on earth were spread over … Read more

Sometimes an island appears out of nowhere, when a volcano under the ocean erupts or when the ocean bed buckles and pushes land to the surface of the water. But islands can disappear too, when the ocean bed buckles and pulls land under the water. Falcon Island, which is really the peak of a volcano, … Read more

Earthquakes with a Richter scale reading of more than 5.5 have caused great loss of life and property, and quakes with a 7.0 reading almost always cause massive destruction. A number of quakes that took place during this century have measured over 8.0 on the Richter scale. The two most powerful measured 8.9 on the … Read more

Scientists measure the strength of an earthquake with a machine called a seismograph, which takes its name from seismos, the Greek word for an earthquake. The seismograph basically consists of a very delicate metal arm with a needle or pen at the end, which rests on a moving drum of paper. When the earth is … Read more

You won’t find a place called Gondwanaland on any map of the world. Gondwanaland, or simply Gondwana, is the name scientists use for one of the huge land masses, that existed before the continents began to drift apart. According to some scientists, all the continents once formed a single land mass, called Pangaea. This land … Read more

If you wanted to get away from it all, the best place on earth to go would probably be a small island in the South Atlantic Ocean called Bouvet Island. This island was discovered in 1739, but not a single person lives there today. Bouvet lies about 1,050 miles away from the nearest piece of … Read more

The expression, “it’s a wide, wide world,” is certainly true, for the surface area of our planet is about 200 million square miles! But a more important question is: How much of the earth’s surface is usable by man? About three-quarters of the earth’s surface is covered by water. Of the 57 million or so … Read more

Water cannot burn. If you see a fire burning on top of a body of water, you can be sure that there must be something floating on top of the water. For instance, oil can float on top of water, and this layer of oil can indeed burn.

Travelers in swampy areas have often seen a strange bluish flame that appears suddenly, moves along the ground, and disappears as suddenly as it appeared. Sometimes, this light is seen in graveyards too. In earlier times, people thought that the flame was a spirit, or a light carried by a spirit, and many superstitions grew … Read more

Each time you take a breath, you breathe in about one pint of air. A standing or sitting adult takes from 16 to 20 breaths a minute, but an adult lying down may take only 13. And a child may take 35 breaths per minute. On the average, a person takes about 22,000 breaths each … Read more

The answer to both questions is yes, if you calculate the date according to calendars other than the one we use! We number our years from the supposed date of Christ’s birth. But Jews count their years from the date of creation, which ancient scholars claimed took place in the year 3761 B.C. So, the … Read more

In 46 B.C., Roman ruler Julius Caesar put a new calendar into effect, which came to be known as the Julian Calendar. The Romans thought that the year was 365.5 days long, so they made an ordinary year 365 days and added an extra day every fourth year, or leap year. But by the year … Read more

We’ve all looked at the globe and studied the shape and position of the land masses called continents. But the size and the shape of the continents have not been the same during all of the earth’s history. Parts of the continents were once covered with water, while parts of the sea were once dry … Read more

No, the earth is not a perfect sphere. It’s actually squashed in a bit at the poles, and widest at the equator. The diameter of the earth, an imaginary line drawn through the center of the earth from one side to the other, is about 7,926 miles at the equator, but only about 7,900 miles … Read more

Nothing can burn on earth without the presence of oxygen. As what we call “fire” or “burning” is a chemical reaction in which atoms of oxygen combine with atoms of carbon from the fuel, the substance being burned, to produce carbon dioxide, light, and heat. Since fire needs oxygen, and there is almost no oxygen … Read more

The earth’s atmosphere is the envelope of gases that surrounds our planet and revolves with it. Most of the gases are within about 300 miles of the earth’s surface, but a thin atmosphere extends some 22,000 miles! Up to a height of 60 miles above the earth, the atmosphere is mostly nitrogen and oxygen. About … Read more

No, it’s not really very cold, and it’s not really very hot, either. It all depends on where in the atmosphere you are! The earth’s atmosphere consists of layers of gases. The lowest layer, called the troposphere, extends to a height of seven miles, and this is the layer in which all our weather takes … Read more

The tundra isn’t really a particular place on earth. It is a type of climatic region, just as a desert is. In fact, tundras are sort of “cold deserts”, vast, flat tracts of land near the Arctic region, the northernmost parts of Siberia, Scandinavia, Alaska, and Canada. A tundra is a cold, barren place, where … Read more

Sailors in the Mediterranean have long marveled at the image of distant castles hovering over the sea near the city of Messina, Sicily. But as the sailors neared the image, it moved away from them or completely disappeared. They thought this illusion was a trick played by an evil fairy named Morgan Le Fay. So … Read more

Sometimes a person wandering in a desert may be so thirsty and sun- parched that he begins to see things that aren’t there. This is a hallucination, and not a mirage, for mirages really exist, and can be seen by anyone in the area at the time they appear! A mirage is a trick of … Read more

Each year, thousands of people journey to New Mexico to see Carlsbad Caverns, the largest caverns on earth. These huge underground caves were formed by water dripping from the ground through layers of rock salt and limestone, dissolving the rock and hollowing out the caves. The caverns may be close to five million years old! … Read more

You probably would guess that the Himalayas, which contain 96 of the 109 tallest mountains, is the greatest mountain range on our planet. Actually, the earth’s greatest mountain range is the Atlantic Ridge, which runs north and south under the Atlantic Ocean, from Iceland almost to the Antarctic Circle. This range is 10,000 miles long, … Read more

Lake Huron is one of the Great Lakes, on the border between the United States and Canada. In the Canadian part of the lake, there’s an island called Manitoulin, the largest island in the world that lies within a lake. And on this island is a lake, called Lake Manitou, that might be called a … Read more

Any solid can change to a liquid if it becomes hot enough, and the temperature at which a solid becomes a liquid is called the melting point of that substance. The temperature at which a liquid turns into a gas is called the boiling point. The freezing point of water is 32 degrees F., that’s … Read more

The word “laser” is an acronym, a word formed from the first letters of a series of words. “Laser” actually stands for “light amplification by stimulated emission of radiation.” Invented in the 1950s, the laser is the most powerful source of energy man has discovered. To create a laser beam, light is focused on a … Read more

When it’s 20 degrees centigrade, of course. Twenty degrees centigrade is the same as 68 degrees Fahrenheit, or just about room temperature. Most of the world uses the Centigrade system today, but the Fahrenheit system is much older. This temperature measurement system was named after Gabriel Fahrenheit, a German scientist who was born in 1686. … Read more

Tornadoes have been reported in every state in America, and have occurred in every season! But most tornadoes occur from April to June, and especially strike in the southern states. In recent years, Oklahoma has had the most tornadoes in terms of area: about eight tornadoes for every 10,000 square miles. Mississippi has had the … Read more

Tornadoes, those powerful funnel-shaped windstorms, move along at about 30 miles per hour, carrying winds that may gust up to 200 miles per hour. Most tornadoes follow a path about a quarter- mile wide and 15 miles long, and last less than 20 minutes. But some especially powerful tornadoes move along at more than 40 … Read more

Lightning is caused by electrical charges that build up in the clouds during a thunderstorm, then erupt in a bolt of electricity that reaches between two clouds, or between the clouds and the earth. When a lightning bolt streaks between clouds and the earth, it usually reaches the ground by first striking a tall object, … Read more

The bright flashes of lightning you see streaking across the sky are usually about 300 feet long, but some very powerful bolts may be over five miles long. And lightning bolts can streak to the ground from eight miles in the air, or leap between two clouds 20 miles apart. A lightning bolt may look … Read more

The center of the earth is thought to contain a core of solid iron with a radius of about 850 miles. Surrounding this central core is an outer core of liquid iron, about 1,200 miles thick. And surrounding this outer core is the earth’s mantle, which is about 1,800 miles thick. The crust of the … Read more

Anyone who has been to the Grand Canyon in Arizona would have trouble believing that the awesome gorge isn’t the deepest on earth. True, the Grand Canyon is the largest canyon in the world, over 215 miles long and more than 12 miles across at some points, but the Grand Canyon is “only” about 7,000 … Read more

Icebergs are pieces of ice that break off glaciers or polar ice sheets and drift in the water with ocean currents. Icebergs are being formed continually, and are not rare at all. In fact, they’re so numerous that each year more than a thousand icebergs drift all the way down to the temperate zones. Large … Read more

Antarctica is the continent that surrounds the South Pole. This cold, barren land covers about five million square miles, that’s about 11/2 times as big as the United States. Yet except for only a few hundred square miles along the coast, the entire continent is continually covered with ice. No, we can’t really call a … Read more

If you hear someone describing a bad winter hailstorm, you can be pretty sure he’s either lying or mistaken, for it almost never hails in winter. Hailstones rarely form unless a thunderstorm is brewing. Hail is caused by the same cloud conditions that usually cause rain in a thunderstorm, except that with hail, the raindrops … Read more

A blizzard is not just a heavy snowstorm. The word “blizzard,” which is used only in the United States, refers to a snowstorm with very strong, cold winds that whip the snow into a fine white dust. Some blizzards may bring less snow than an average snowfall.

Weather records that include the size of a snowfall have been kept for only about 100 years, so we don’t know the size of the heaviest snow of all time. But in 1921, the heaviest daily snow on record struck Silver Lake, Colorado, dumping 76 inches of snow on that town in 24 hours! The … Read more

When you hear of a “petrified forest,” you might think of trees shaking in the wind, the way a person shakes when he’s frightened, or “petrified.” Actually, this word comes from a term that means “stone.” A petrified tree is really a tree that has been turned into stone! The largest collection of petrified trees … Read more

Niagara Falls, on the border between New York State and Canada, pours about 620,000 tons of water over its edge each minute. But in March, 1847, the waterfall almost came to a standstill. The water of the Niagara River froze over until only a trickle of water was pouring over the falls. People rode nearly … Read more

In some places in the United States, the tap water doesn’t allow soap to form lather, and cannot be used for washing without the addition of chemicals called “water softeners.” This kind of water is called “hard” water, and it’s caused by certain minerals in the water. Sometimes water contains molecules of carbon dioxide gas, … Read more

Weather experts have a tough time finding out exactly how much rain has fallen in some distant parts of the world, so no one is really sure what is the heaviest single rainfall of all time. But we know that an island in the Indian Ocean once received more than six feet of rain in … Read more

Meteorologists, or weather experts, measure rainfall and snowfall in inches. They let falling rain collect in a cylinder, and can tell how many inches have fallen by seeing how far the rain fills up the cylinder. If your weatherman says that an inch of rain fell on your town, it means that if the ground … Read more

It might sound strange to say that rain keeps the earth dry, but that’s exactly what it does. The process that results in rain gathers moisture from the air and concentrates it in clouds, which later deposit the water in the form of rain. If this moisture didn’t condense to form rain, then the atmosphere … Read more

Waves in the deep parts of the sea move like ripples on the surface of the water. When they near land and enter shallow water, they slow down, because deep water always moves faster than shallow water. Waves also grow higher as they near a shore, for in effect the sea bottom is “rising” as … Read more

Tidal waves have nothing to do with the tides, which are caused by the gravity of the moon and the sun. A better term for a tidal wave is a seismic sea wave, or a tsunami, a word which comes from Japan, where tidal waves are common. Tsunamis are caused by earthquakes under or near … Read more