by Bill McLain
My grandmother told me that when she visited Ireland she saw the sun turn green. Is that possible? (Green sun, blue moon, what next!)
It’s not only possible, it does happen. What your grandmother saw is known as a “green flash.”
If it’s very clear when the sun is setting or rising on the horizon, you can see a green flash of light on the horizon that lasts for a few seconds. In order to see it, you need a distant horizon with a distinct edge. That’s why a green flash is typically seen over the ocean. If conditions are just right, you will see a brief flash of green or a green flame that shoots up from the horizon.
When the sun rises or sets, the spectrum of light waves must pass through the greatest atmospheric thickness of the day. Because water vapor in the atmosphere absorbs the yellow and orange rays and scatters the violet rays, only the red and blue-green light travels toward you. The longer red waves are cut off by the horizon but the shorter blue-green rays are refracted, or bent, and linger for a second before disappearing.
Another way to understand the green flash is to imagine four suns, a yellow-orange sun, a violet sun, a red sun, and a blue-green sun. Imagine each one on top of the other like four stacked poker chips standing on edge.
The yellow-orange sun is absorbed by the atmosphere and disappears. The violet sun is scattered and disappears, leaving only the red and blue-green suns. The red sun is closer to the horizon than the blue-green sun and it sets first, followed almost immediately by the blue-green sun. In that instant, you can see the upper part of the blue-green sun which appears as a green flash.
One scientist always looks for a green flash whenever there is a clear horizon. After ten years of looking, he is still waiting to see it. It is indeed rare to observe a green flash.
FACTOIDS
The temperature of the sun can go as high as 15 million degrees Fahrenheit. The coolest parts of the sun are about 10,000 degrees Fahrenheit.
Like people, stars are born, mature, grow old, and die. Our sun (which is a star) is middle-aged.
The sun contains over 99.8 percent of the total mass in our solar system, while Jupiter contains most of the rest. The fractional percentage that is left is made up of our earth and moon and the remaining planets and asteroids.
When light rays are scattered because of atmospheric haze, results can be more than just beautiful sunsets. For instance, after the volcanic island of Krakatoa exploded, the moon actually looked blue. (There is no proof that this is the origin of the expression “a blue moon,” however. This phrase was used long before the explosion of Krakatoa.)
DID YOU KNOW?
Many ancient cultures have worshipped the sun, including the ancient Egyptians, Mayans, Incas, and Hindus. In our country, Native Americans such as the Hopi and Zuni revered the sun. In Japan, the royal family was believed to have descended from the sun goddess, Amaterasu.
Scientists believe that the mysterious stones at Stonehenge in England are actually a solar observatory built almost 5,000 years ago. Another ancient method of identifying important times in the sun’s orbit around the earth is a simple spiral rock carving in New Mexico’s Chaco Canyon. At noon on the day of the summer solstice, the center of the spiral is penetrated by a dagger of sunlight. At the winter solstice, a dagger of sunlight strikes each side of the spiral.
A controversial archeological site is the Bighorn medicine wheel in northern Wyoming (so named because Native Americans often use the name “medicine” for an object believed to give control over natural or magical forces). The wheel, made up of rocks carefully positioned on the ground, has 27 spokes and a circumference of 245 feet. Scientists believe it was constructed about 2,500 years ago.
It’s not just the wheel that is intriguing. All across Wyoming giant stone arrows point the way to the medicine wheel. Some of these arrows are 200 miles away. It appears that some ancient peoples wanted to make sure that anyone could find the wheel, but the wheel’s importance is unknown today.
Perhaps scientists will one day unlock the secrets of the Bighorn medicine wheel.
How are magnets made? (Are people attracted to you because of your magnetic personality?)
First you need an object that can be magnetized. Wood or glass, for example, cannot be magnetized. Any material that can be magnetized is called ferromagnetic. “Soft” ferromagnetic materials will lose their magnetism once they are removed from a magnetic field, while “hard” ferromagnetic materials such as iron retain their magnetism. The only three elements that can be permanently magnetized are iron, nickel, and cobalt. Some elements, such as chromium, exhibit paramagnetism, which means they can only be made into a very weak magnet.
To make a magnet out of a piece of ferromagnetic material, you must place the object in a magnetic field. As the field cuts through the object, most of the electrons within the material are aligned in the same direction, and the object becomes magnetized. An object can be placed in a magnetic field in one of two ways.
The first method is simply to stroke the object with another magnet. The second method is to pass an electric current through the object; an electric current creates a magnetic field. This method is used to create industrial electromagnets.
An electromagnet is a large coil of wire wound against a soft ferromagnetic core. It is usually hung from some type of crane. The core remains magnetized only while an electric current flows through the wire. One use of industrial electromagnets is in automobile wrecking yards. The crane is positioned so that the electromagnet touches the top of the automobile. When the electricity is turned on, the magnet lifts the automobile. The crane is then swung around to where the automobile is to be placed, the electricity is turned off, and the automobile drops into the desired spot.
In recent years scientists have come up with a number of alloys to produce small but extremely powerful magnets. An alnico magnet, for example, is an alloy of aluminum, nickel, and iron. Some powdered materials are also made into magnets. Barium ferrite magnets, for example, are used as the focusing magnets for television tubes.
FACTOIDS
The earth can be thought of as a giant magnet. A compass helps us find directions because it can point to the earth’s magnetic pole. Earth’s magnetic field is also the cause of the spectacular aurora borealis, or northern lights.
Natural magnets have been used for over 3,000 years.
Today’s computers would not be possible if not for magnets. The computer’s memory and all storage devices such as disks and tapes are made of tiny magnets.
More than half of the permanent magnets in the world are produced by Japan.
A typical home contains at least 150 magnets, found in electric motors, loudspeakers, microwave ovens, CD players, VCRs, and computers.
Experimental high-speed trains in Japan use magnetic levitation to allow the trains to float above the track, thereby eliminating the friction that would slow them down.
DID YOU KNOW?
The ancient Chinese and Greeks knew about rare and mystical stones with the power to attract iron. These were natural magnets of iron-rich ore called “lodestones.” This was the only form of magnetism known until 1821.
The first Greeks to discover the lodestone lived near the city of Magnesia. This is where the word “magnet” comes from, meaning “the stone of Magnesia.” Milk of magnesia was also named after this city but it doesn’t contain any magnets.
Around a thousand years ago, the Chinese found that stroking a steel needle with a lodestone caused it to become magnetic. They also found that if the needle was freely suspended, it would always point north-south. Thus the compass was invented.
The magnetic compass was soon introduced to Europe and Columbus used it when he crossed the Atlantic.
It’s difficult to tell where Columbus might have landed without a compass. He could have landed anywhere. And if that had happened, the Spanish and later the British might have colonized some other land and where would the United States be today? Magnets can be extremely important.
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nbsp; What makes the sound when you snap your fingers? (Shame, shame on you.)
When you rub two fingers together, the loudest sound occurs when the air is forced out between the middle finger and the palm and the air strikes the palm. You can test this theory by first snapping your fingers and listening to the sound. Next, place a soft tissue or piece of cloth on your palm and try snapping your fingers. The sound will be very muffled.
Our fingers have many uses outside of the obvious ones. We rub two fingers together when we say “shame on you.” Some authorities believe that this gesture evolved from the practice of crossing two fingers to make the sign of the cross in order to ward off evil. The finger strokes in the “shame on you” gesture symbolize pushing away or repelling the evil one.
Our decimal numbering system, which has 10 numbers, is based on our fingers. Ancient people kept track of things by counting on their fingers. Because we have 10 fingers, we devised a numerical system based on 10 digits. In fact, the word “digit” can mean either a finger or a number. Some cultures, however, used a different numerical system. The ancient Mayans, for example, used a system with 20 digits rather than 10.
Some cultures use their fingers to do complex arithmetic. Koreans have a “finger math” that is also taught in some places in the United States. Teachers who work with visually impaired students teach this Korean “finger-calculator method,” called “chisanbop,” that lets students do multiplication problems such as 18 times 26 using nothing but their fingers.
One of the most fascinating features of our fingers is our fingerprints. Every person in the world has a unique set of fingerprints, unlike any other. However, most experts believe that identical twins have identical fingerprints 95 percent of the time. The use of fingerprint identification has become a major tool in apprehending criminals.
FACTOIDS
Latent fingerprints (the prints left at a crime scene as opposed to those on a fingerprint card) can be left on any surface, including paper and human skin. Some techniques used to make latent fingerprints visible include lasers, powders, alternate light sources, and subjecting them to glue fumes.
In ancient Babylon, fingerprints on clay tablets were used for business transactions; in fourteenth-century Persia, many government papers had fingerprints on them; and in Nova Scotia, a prehistoric picture shows a hand with ridge patterns.
Wearing latex gloves does not necessarily keep a criminal from being apprehended if the criminal leaves the gloves at the crime scene. When tight-fitting, nonporous gloves are removed, fingerprints remain on the insides of the gloves and can be detected by a number of different methods.
The first mention of fingerprints occurred in 1686 when a professor of anatomy, Marcello Malpighi, described the ridges, loops, and spirals of fingerprints. In 1823, another professor of anatomy, John Evangelist Purkinji, described 9 basic fingerprint patterns. However, neither man considered using fingerprints to identify individuals.
DID YOU KNOW?
Prior to using fingerprints to identify individuals, a system of measuring bony parts of the body was used. This system was devised in the late 1800s by Alphonse Bertillon, a French anthropologist. Bertillon measured certain bony body parts and then used a formula to come up with a value that would apply to only one person in the world and would not change during that person’s lifetime. This technique, named the Bertillon system after its inventor, was accepted as valid for 30 years.
In 1903, a bizarre event triggered the end of the Bertillon system. A man by the name of Will West was sent to the federal penitentiary in Leavenworth, Kansas. The problem was that the penitentiary already had an inmate named William West. When photographs of the two men were compared, they were identical. When the authorities used Bertillon measurements, they indicated that both men were the same person. Finally, their fingerprints were compared, proving they were indeed two different individuals. When authorities reviewed prison records and correspondence from the men’s families, they discovered that Will West and William West were identical twins.
In that same year, the New York state prison system began using fingerprints to identify criminals, and a year later fingerprint identification was started at the Leavenworth penitentiary.
Thanks to the West brothers, today we only have to put an inked thumbprint on a piece of paper rather than have all of our bony body parts measured.
Does hot water freeze faster than cold water? (Should you heat the water to cool it faster?)
This is a frequently asked question. If both the cold and hot water are identical in composition, then the cold water will freeze faster. However, 50 percent of people asked this question believe just the opposite. Why?
People tend to think that hot water will freeze faster because they are basing their opinion on real-life experience. When water is boiled until all the trapped air bubbles are released, it will freeze faster than cold water. But hot water doesn’t freeze faster because it’s hot but because it has a different composition from the cold water that still has the trapped air bubbles.
When you heat water you promote evaporation that causes two cooling effects. First, some of the mass is carried off so there is actually less water to be cooled. Second, during evaporation the hottest molecules are released into the air first, thus lowering the temperature of the remaining water. This is why you can cool your soup by blowing on it. When you blow on the soup, it removes the water vapor hovering above it and helps evaporation.
The folklore about hot water freezing faster probably started more than a century ago when water was carried in wooden buckets, which help retain the heat and increase evaporation. Nowadays, when water is kept in a metal bucket, a large amount of heat is transferred through the metal sides and cooling is not dependent on evaporation. In a modern experiment using wooden buckets a bucket of hot water froze 10 percent faster than a bucket of water at room temperature.
FACTOIDS
It takes about 1,500 gallons of water to produce a typical fast-food lunch of a hamburger, french fries, and a soft drink. This includes the water required to raise the potatoes and the grain used to make the bun and feed the cattle.
Your body requires about 9 glasses of water a day. You can be dehydrated by 5 percent before you even feel thirsty.
The volume of water on earth today is the same as it was 3 billion years ago.
Two thirds of your body and three fourths of your brain are water.
Of all the water on the earth, only 1 percent is available for human consumption.
On average, you use about 2 gallons of water just to brush your teeth and from 4 to 6 gallons every time you flush the toilet.
About 39,000 gallons of water are needed to manufacture a domestic automobile.
DID YOU KNOW?
When we think of water, we usually think of a liquid. However, when water is solid, it’s ice. The largest and most impressive ice is in the form of gigantic icebergs that float in the North Atlantic Ocean.
The tallest known iceberg was sighted in 1967 near Greenland. It was 550 feet tall, or taller than a 50-story skyscraper. Another ice berg was approximately the size of the entire state of Rhode Island.
Most icebergs come from glaciers on the western side of Greenland. Between 10,000 and 15,000 icebergs shear off from these glaciers every year.
Icebergs have always been dangerous to ships because about 90 percent of the iceberg is hidden below the waterline, making it difficult to see how large it is. However, modern devices such as radar and satellites minimize the danger.
Nevertheless, to be safe, if you decide to take an ocean cruise in the near future, you should do so in the summer, and go south rather than north. A cruise in the South Pacific Ocean would be even better.
Why do some paints, stickers, and toys glow in the dark? (Have you ever seen a real frog glow?)
A material that glows in the dark after being exposed to light contains molecules that absorb energy for long periods of time, then later release that energy as light. The phenom
enon is called “phosphorescence” and the materials are said to be “phosphorescent.”
Electrons in a molecule are normally arranged in a state of the least possible energy. However, when a molecule is exposed to light it may absorb a particle of light, called a “photon.” The photon rearranges the electrons to a highly energetic state. If the material is phosphorescent, the extra energy from the photon becomes trapped in the molecule. Eventually, the electrons shift to a lower energy state and the extra energy that had been trapped is released as a photon of light.
Electrons escape randomly rather than all at the same time. As these higher-energy electrons release light to return to their original states, fewer and fewer are left to escape. That is why the glow continually diminishes until it fades into nothing.
Three types of substances can glow in the dark. The first is the phosphorescent material that absorbs light and then gradually releases it, like the phosphorescent material we just described.
The second type can emit light without any outside help. For example, the firefly has the rare chemical luciferin and the enzyme luciferase in its abdomen. These interact with oxygen to produce the glow.
Radioactive materials are the third type. These emit high-energy rays that react with surrounding materials to produce light. Radium is a good example of a radioactive material that gives off light.
Around 1852 the term “fluorescence” was coined. Phosphorescence refers to a material that absorbs light and releases it over a period of time. Fluorescence refers to a material that absorbs light in one spectral color and immediately emits light in a different spectral color. If you’ve ever seen a mineral glow under an ultraviolet light (black light) then you’ve seen fluorescence.
