What are the most abundant components of seawater?
Other than the hydrogen and oxygen that make up the water molecules, the most plentiful element in seawater is chlorine, mostly in the form of the chloride ions (charged atoms) that make up one half of the salt (mostly sodium chloride) dissolved in the water. The other half of the dissolved salt is mostly composed of sodium ions, but there are also ions of potassium and other metals that combine with the chloride ions to form various kinds of salt. In general, for every hundred molecules of water there is about one ion of chloride and one ion of sodium. Seawater also contains hundreds of other kinds of atoms and ions, including magnesium, calcium, bromide, carbonate, sulfur, iron, silicate, and dissolved gases such as oxygen, nitrogen, and carbon dioxide. In trace amounts, there are even small amounts of gold, silver, uranium, copper, tin, and many other rare metals. University pages about seawater, what's in it, and how it got there
Saltwater aquarium enthusiasts know that water composition is critical
More Cool Facts about seawater
What kind of eyes does a starfish have?
From the look of it, you might think that a starfish has no eyes. But in fact, it has an eye on the end of each arm. Most starfish have five arms, so they also have five eyes, but some starfish have as many as twenty arms (or more), and as many eyes. The very simple eyes of a starfish are unable to form images. Each eye is a tiny spot of red pigment that is sensitive to light. Nerves run from the pigment spots to the starfish's central nerve ring. The signals from the eyespots affect the animal's behavior, enabling it to avoid light that is too bright and change its light preferences according to the time of day, water chemistry, and other factors. Since a starfish has no brain, it would not be able to make much use of images, even if its eyes were able to form them. More about starfish
Another Cool Fact about starfish
What's the closest spacecraft fly-by so far?
On July 28, 1999 the spacecraft Deep Space 1 (DS1) passed within ten kilometers (six miles) of a tiny Asteroid called 9969 Braille, in the closest non-impact fly-by to date of a spacecraft past any celestial object. Moving at a relative speed of 15.5 kilometers per second (nearly 35,000 miles/hour), DS1 zoomed past Braille more than 50 times faster than the speed of a commercial jet, and twice as fast as the Space Shuttle. Deep Space 1 is part of NASA's New Millennium Program, a group of missions designed to test and refine new space technologies. DS1 tests twelve new inventions, including a revolutionary ion propulsion system and a sophisticated software navigation system. The official DS1 web site
The New Millennium Program
More Cool Facts about Deep Space 1
Who made the first marbles?
Marbles have been used for games since the times of the Egyptian Pharaohs, when they were made out of fired clay. Clay marbles were also made by Native Americans, who also used round stones and nuts for their games. The first glass marbles were made in Venice, Italy around 900 AD. Italian marbles were also made out of polished marble and other kinds of stone around the same time. These stone and glass marbles were used throughout Europe for hundreds of years. Modern glass marbles did not appear until about 1860, when they were made in Germany. Around 1905, machine-made marbles were first sold in the United States, and their higher quality seriously impacted the European handmade marble marketplace. Today, though, the very best marbles are still made by hand, using secret methods. More about marble history and collecting
Another Cool Fact about marbles
Marble is a Cool Word
Where is the largest temperate rain forest?
The largest unbroken temperate rain forest in the world is the Tongass in southeast Alaska. It is 17 million acres of magnificent wilderness with abundant birds, bears, and other life. How wild is it? Surrounded by the Tongass, the city of Juneau (Alaska's capital) is accessible by ferries or by air, but not by roads. The Tongass was extensively logged until the early 1990s, when the lumber mills began to shut down. Today, almost the entire region is protected from further development or exploitation, and many groups act to further that protection. Temperate rain forests (those outside the tropics) look different than tropical rain forests. Dominated by coniferous trees, they grow more slowly but have a larger biomass (total mass of living matter) than tropical rain forests. More about the Tongass
Resource pages for protection of the Tongass
More Cool Facts about forests
Where is the coldest place on Earth?
The coldest natural outdoor temperature ever recorded (as of January, 2000) was at Russia's Vostock Station in Antarctica. In 1997 the temperature there fell to -91 degrees Celsius (-132 degrees F). At this temperature, steel becomes so brittle it shatters easily. Vostok Station is located in the middle of a vast expanse of uninterrupted ice, on a high plateau about 780 miles (1260 km) from the South Pole. The ice at Vostok is about 3700 meters thick (12,100 feet) and the surface elevation is 3488 meters (11,444 feet). Vostok Station is not only the coldest place on Earth, it is also one of the driest. Because the air is so cold, it can hold very little moisture. The air's absolute humidity at Vostok is lower than that of the Sahara Desert. More about Antarctica, by a scientist who spent a year at the South Pole
More Cool Facts about Antarctica
What's the slowest pulsar discovered so far?
A pulsar is a spinning neutron star that casts a tight beam of electromagnetic energy around the Galaxy like a searchlight. Until recently, it was thought that in order to create the beam of energy a pulsar had to spin at least several times each second. But a newly discovered pulsar, called PSR J2144-3933 spins only once every 8.51 seconds, making it the slowest pulsar known. Pulsars are thought to generate their energy beams through the reactions of electrons and positrons (anti-electrons) produced by the star's gigantic magnetic field. But PSR J2144-3933 is not spinning fast enough to make an energy beam by that process, according to the scientists. Its energy source remains unknown, and the scientists continue to watch it carefully, hoping for more clues. More about PSR J2144-3933
More Cool Facts about neutron stars
How were Popsicles invented?
Until 1905 the world had no Popsicles. It was in that year that 11-year old Frank Epperson of Oakland, California invented the popular treat by accident. He had mixed up some powdered soda pop, but he left the cup outside with the stirring stick still in it. That night there was a record frost. When Frank went outside the next morning, there was his cup with the soda pop frozen solid. He grabbed the stick and the frozen pop came out of the cup in one piece. Eighteen years later Epperson started selling "Eppsicles." The Eppsicle was eventually called the Popsicle, a trademarked name for what is also known as an ice pop. Today they are sold on thin hardwood sticks, and they have evolved into hundreds of varieties including chocolate dipped ice cream pops (Creamsicles), with or without sprinkles. More about the invention of the Popsicle http://more.abcnews.go.com/sections/tech/Geek/geek990624.html
More about popsicles and other frozen treats
More Cool Facts about food
Why do birds fly in a "V" formation?
Have you seen seagulls or migrating geese flying in a "V"? Through evolution, flocks of birds have spontaneously developed the best instinctive strategy for long-distance flight as a group. Freeway drivers may be familiar with the "wake effect" that reduces gas usage when one follows just behind and to one side of a large truck. The "V" flying flock takes advantage of exactly the same effect. By flying in a "V", birds minimize the energy used by the whole flock to get where it's going. Recent research shows that even the leader of the "V" benefits from the formation. A "V" flock of 25 birds can travel 70% farther than an unformed flock, and it also flies faster. More about formation flying by flocks
Even today, bird flight is still quite mysterious
More Cool Facts about flying birds
What's so special about laser beams?
Laser stands for "Light Amplification by Stimulated Emission of Radiation." A laser beam is produced when light bounces back and forth between two mirrors with a special medium (gas, liquid, or solid) between them. As it bounces, the light triggers energized atoms in the medium to release more light, some of which leaks out through one of the mirrors to produce the laser beam. A laser beam is special because all the photons (discrete "particles" of light energy) in the beam are vibrating in exactly the same lockstep way. The beam is tightly focused and perfectly aligned because all the photons are "marching in phase" like soldiers in a troop. In an ordinary beam of light, the photons vibrate every which way. Because laser photons are in phase, the beam can stay aligned for very long distances and it can be focused down to a very tiny spot without losing its alignment. How lasers work, from a company that does spectacular laser light shows
This site has lots of detailed technical information for experimenters
Person Of The Day is laser researcher Kumar Patel
More Cool Facts about lasers
What were the largest birds that ever lived?
When humans first came to the island of Madagascar around 600 AD, it was home to the largest birds that ever lived, the giant, flightless elephant birds (Aepyornis maximus). The last one probably died about 800 years ago. The liquid capacity of one elephant bird egg was about two gallons (7.5 liters), 180 times that of a chicken egg, possibly making it the largest single cell ever. An adult bird probably weighed about one thousand pounds (450 kilograms). Like their living cousins the ostriches, they were running birds with thick, muscular legs and vestigial wings. The elephant birds were among many species of large animals that disappeared from Madagascar after humans arrived. Today, the island's animal life is much reduced. Destruction of habitat has eliminated many species, and many more are threatened. More about the gigantic elephant bird
The elephant bird was a ratite
Cool Facts about ostriches, the largest surviving birds
What common affliction was almost unknown before 1800?
Many people experience sniffling, sneezing, and itchy eyes during certain times of year. This affliction, known as allergic rhinitis or "hay fever," was almost completely unknown until the last century or so. Today it affects one third of Americans and 40% of Australians. Hay fever results from the body's reaction to particles carried in the air, including especially pollen grains and mold spores. Pollen and mold spore levels have not changed much in the last century, so why has hay fever become so widespread and severe? No one knows for sure, but there are several theories. Fewer childhood infections may leave the body more sensitive to foreign particles, and increased pollution may make the situation worse. It may be that the body needs to be exposed to high levels of allergens in early life in order to learn how to "recognize" them so they don't cause problems later on. More about hay fever
Another Cool Fact about spores and pollen
How can a cricket be used as a thermometer?
If you hear a cricket chirping and you have a watch, you can estimate the temperature where the cricket is. If you can hear more than one, you can tell whether they are experiencing different temperatures. To calculate the "cricket temperature," count the number of chirps in a 14-second period. Add forty to the result, and you have a rough estimate of the Fahrenheit temperature of the cricket. This method works best with the snowy tree cricket, whose song sounds like gently ringing sleigh bells. Depending on the species of cricket, you might have to adjust the counting time by one or two seconds, up or down. Why does it work? Because crickets are cold-blooded creatures, the rate of their metabolism is strictly determined by temperature. The warmer it is, the faster they move and the faster they chirp. The same method would work equally well with other insects if they had the regular chirping habits of crickets. More cricket lore, and how to keep them as pets http://freeweb.pdq.net/headstrong/cricket.htm
Scroll down this page to read about crickets
Crickets and their relatives, grasshoppers and katydids
Another Cool Fact about crickets
What country has the most tornadoes?
The country with the most tornadoes is the United States, where about 800 twisters touch down every year. Most of them happen in the central plains states ("Tornado Alley"), where gigantic "supercell" thunderstorms sweep across the landscape, fed by moisture from the Gulf Of Mexico colliding with cooler, dryer air from the Rocky Mountains. The second place winner for most tornadoes is Australia, where a few hundred form every year. They also happen sometimes in the plains of Asia. Tornadoes can happen in any country that gets thunderstorms, but they require very special conditions. A heavy layer of cool, dry air must flow above a layer of warm, moist air, and there must be a certain twist to the air currents to start the vortex spinning. The National Weather Service's page on tornadoes
More Cool Facts about thunderstorms
How was Play-Doh invented?
For more than 40 years kids have been making monsters, dogs, people, and shapeless blobs out of Play-Doh, a curiously aromatic stuff that comes in different colors. Today it's a multi-million dollar product made by Hasbro, but how did it get started? It happened in Cincinnati, Ohio in the 1950s, and involved a young man named Joe McVicker. McVicker's sister-in-law was a schoolteacher who wanted softer clay for her young students, who were having trouble molding the hard, water-based mineral clay that was used in schools at that time. McVicker took the request to a biochemist named Tin Liu at his father's soap and chemical company. Starting with a soft, gooey substance used to clean wallpaper, Tin Liu came up with Play-Doh. McVicker marketed the result, and became a millionaire by the time he was 27. No one seems to know what happened to Tin Liu, who seldom gets credit as Play-Doh's actual inventor. Two slightly different versions of the Play-Doh story http://www.yolk.com/magazine/iss1/doh.html
Recipes for home-made clay, play-doh, and more
More Cool Facts about toys and games
What human bone serves no known purpose?
Everyone has a bone that serves no purpose we know of. It's the coccyx [KOK-siks], a small triangular bone at the very end of the spine. Millions of years ago, our distant ancestors had tails that helped them balance while they moved around in the trees, much like today's tailed monkeys. When they moved from the trees out onto the grasslands of Africa, our prehuman ape ancestors began to stand upright, and the tail diminished to a tiny stump, and then to nothing at all. But the bone that was in the tail is still with us, even though there are no muscles attached to it. Such a left-over of a once-useful organ is called a vestigial [ves-TIJ-yul] organ. Another organ that may be vestigial is the appendix, a small extension of the intestine that may have once helped filter toxins from our food. Diagram of the spine, showing the coccyx at the end http://reality.sgi.com/sambo/Oobe/CyberAnatomy/HTML/coccyx.html
More about the spinal bones, including the coccyx http://homepages.which.net/~ks.burrell/f2/spine.htm
More Cool Facts about bones
What's the world's largest herb?
An herb is a vascular plant (a plant with water-carrying vessels) that does not have woody tissue (stem tissue in which the cells have died but still carry water). The largest herb in the world is the banana plant (Musa sapientum), a crop grown in tropical countries around the world. Banana plants have leaves up to four meters long (12 feet) that emerge from an underground corm. The bananas are formed in a large bunch called a hand that forms on the end of a sturdy stem. The fruits of domestic bananas do not contain viable seeds; the plants are reproduced by dividing the corm or by growing tiny plantlets in laboratory tissue cultures. The average American eats 28 pounds (13 kg) of bananas in a year, more than any other fruit. Worldwide, about 60 million tons of bananas are produced each year. An acre of banana plants can produce as much as seven tons of fruit in a year.
More about bananas
Did you know bananas can ease muscle cramps?
Why does a candle flame have different zones?
Take a close look at a candle flame. How many different zones does it have? From the wick outward and upward, first there is a transparent zone, then usually a blue zone, then a yellow zone, and possibly a short red one. Sometimes there is even a black zone after that one. The transparent zone nearest the wick is where wax vapor steadily streams off the wick. There isn't enough oxygen in that zone for it to burn, because the steady stream of vapor keeps it out. But something else important happens here: the heat from the burning part of the flame starts breaking up the chains of carbon atoms in the wax. The long chains of carbon atoms immediately condense into extremely tiny particles of soot, which are carried into the main flame. The blue zone is colored by the burning of a particular kind of molecular fragment called diatomic carbon (C2). The yellow zone is colored by the burning of the soot particles. If not all the soot burns, then the red zone forms from cooling soot particles, and you might even see the black zone which is smoke (large soot particles) in the process of condensing. A more detailed explanation
More about soot and candle flames
More Cool Facts about fire
What kind of laser makes the cleanest cut?
The kind of laser cutter that causes the smallest amount of damage to the material surrounding the target is the femtosecond laser, developed in 1997 by a team at the Lawrence Livermore Laboratory. The secret to the clean cuts of the femtosecond laser is the extremely short duration of its light pulses -- 50 to 100 femtoseconds (a femtosecond is one quadrillionth of a second). Because the pulse of light is so short, it only removes one layer of atoms with each pulse. These atoms are almost instantly vaporized and blown free of the target zone. By the time they are gone, the laser pulse is over and no further heat is added. The femtosecond laser has applications ranging from cutting steel to performing delicate microsurgery operations. It was originally developed for use in disassembling nuclear weapon components, which must be done very carefully and precisely. More about the femtosecond laser
A research group in Germany is developing new applications:
More Cool Facts about lasers
Where's the largest pipe organ in the world?
Built between 1929 and 1932, the largest pipe organ in the world is the Atlantic City Convention Hall Organ, in Atlantic City, New Jersey, USA. According to the Guinness Book of World Records, it is also the largest and loudest musical instrument ever constructed. The monster music maker has 336 stops (tuned sets of pipes that form musical voice settings), and is powered by blowers totaling more than 600 horsepower. The exact number of pipes is not known; the quoted figure is 33,112 but some experts estimate the number at more than 32,000. The main playing console, which is surrounded by art-deco columns with stylized flames on top, boasts seven keyboards and rank upon rank of stop controls. There are six large foot pedals and dozens of small ones. The pipes are located in chambers that fully surround the auditorium, so the audience is completely immersed in the musical experience. The Atlantic City Convention Hall Organ Society
Much more about pipe organs
Another Cool Fact about an extreme musical instrument http://www.cool-fact.com/archive/1998/06/22.html
How do the two poles of Mars differ?
Recent discoveries made by the Mars Global Surveyor spacecraft show that the two poles of Mars are very different, indicating that the climate may have been different at the two poles for quite a long time. The south pole has a permanent cap of frozen carbon dioxide mixed with layers of other material. Since the carbon dioxide ice evaporates directly into the thin Martian air, rather than melting the way water ice does on Earth, the landscape shows features unlike anything on Earth. There are flat-bottomed circular depressions and round-walled plateaus, and complex fingerprint-like whorls of grooves. The north pole's ice cap, while about the same size, is simply a layer on top of the ground, with small pits probably caused by evaporation of the ice. Its structure seems simpler, and it may be composed mainly of water ice rather than frozen carbon dioxide. Why are the two poles of Mars so different? Scientists hope to discover the answer as exploration of the red planet continues. More about the poles of Mars
More Cool Facts about Mars
How are coins designed and produced?
Modern US coins go through a complicated design process, from the first idea to the final product. It starts with an act of Congress to authorize the new coin. An artist draws a detailed picture of the new design, then a sculptor makes an enlarged, 3-dimensional clay model of the coin. A plaster cast is made of the clay model, and then a rubber mold of the plaster cast. An epoxy coin is cast in the rubber mold, and then a machine engraves a life-size metal proof called a die from the large epoxy cast. Many of these dies are used in a machine called a coin press, which takes circular pieces of metal called blanks and stamps them with the dies, turning them into actual coins. The coins are checked for flaws, and then released to the banks in counted bags. More about how coins are made (for kids...)
(...and for grownups)
More Cool Facts about coins
What kind of train does not touch the track?
A traditional train has metal wheels that ride on steel tracks, but a train that uses magnetic levitation (a maglev train) moves without touching the track. In some maglev designs, the train "lands" when it stops at a station. In other designs, the train levitates (floats in the air) even when it is not moving. Magnetic levitation train designs come in two flavors. In one, magnets on the underside of the train attract magnets or coils in the trackway, suspending the train from a T-shaped support that runs the length of the track. In another design, magnets on the train repel coils in the track, holding the train up in the air over the trackway. Because they do not touch the tracks, maglev trains are faster, quieter, and safer than traditional trains. In most maglev designs, the trains are expected to run at about 500 kilometers per hour (310 mph), two to three times faster than the fastest old-fashioned trains. More about maglev trains
The Japanese project at Railway Technical Institute http://www.rtri.or.jp/rd/maglev/html/english/maglev_frame_E.html
Germany's Transrapid system
More Cool Facts about trains
Why does Australia have such unusual life forms?
The continent of Australia has one of the most unusual collections of native life forms on the planet. Why are there so many strange forms there? 50 million years ago, Australia was part of a land mass near the South Pole. It was connected with what are now Antarctica and South America. As the continents slowly shifted, Australia split off and began a long journey northwards. During that time it was isolated by wide stretches of ocean. In Australia, evolution continued for about twenty million years without interference from new forms emerging on other continents. The climate changed radically several times, and whole families of life forms became extinct while new ones evolved. As a result, Australia developed ecosystems quite different from those on other continents. More about the prehistory of Australia
A detailed research report about Australia's biology
Another long-isolated land with unique life forms is Madagascar
Who first used concrete for large constructions?
Although concrete was known as early as 2,000 years ago, its first use in major construction projects was in ancient Rome. A good example is Hadrian's Villa near Tivoli, Italy, which was built around 120 AD. There, the Roman Emperor Hadrian experimented with various forms and styles of architecture, making use of concrete in conjunction with bricks, tufa, and other materials. The Villa at Tivoli is especially noteworthy because of the interesting use of curves, domes, underground passages, ponds, and other elements. New materials made new forms possible, and Hadrian's Villa shows some of this experimentation in its many interesting vistas. Many Roman buildings made of concrete have lasted through history because of their unique chemistry. The Romans mixed their lime with pozzolan, a kind of ash produced by a certain volcano. The peculiar chemistry of the resulting concrete was one of the reasons for its durability. More about durable ancient Roman concrete
More about Hadrian's Villa http://www.woodberry.org/acad/hist/CLASSICS/sites/purcell/gen.htm
Person Of The Day is Hadrian http://www.LearningKingdom.com/person/archive/2000/04/14.html
When are atoms of an element not identical?
In 1913 a British chemist named Frederick Soddy discovered that not all atoms of each element are exactly the same. Although their chemical properties may be almost identical, atoms of most elements come in several varieties with different masses. These varieties are called isotopes. Different isotopes of an element hold different numbers of neutrons in the nuclei of their atoms. The numbers of protons and electrons are the same. Hydrogen, for example, has three isotopes. Normal hydrogen has one proton in its nucleus. Deuterium has a neutron and a proton, while tritium has two neutrons and a proton. Different isotopes of an element can be separated by mass-sensitive processes like evaporation, condensation, and incorporation into living tissue. As a result, scientists can learn much about the Earth's past by studying the ratios of isotopes in sediments or ice cores. A simple introduction to isotopes
Explore the table of isotopes, courtesy of Lawrence Berkeley Labs
Radioactive isotopes are used to save lives http://www.inel.gov/resources/newsletters/inside/november98/isotopes.htm
Person Of The Day is Frederick Soddy
What's the hottest kind of flame?
The hottest flames known to science are made by burning a mixture of oxygen and acetylene (C2H2). The flame of an oxyacetylene torch can reach a temperature of more than 3300 degrees Celsius (5972 F), hot enough to melt metal even underwater or in the extreme cold of Antarctica. Why does acetylene produce such a hot flame? The secret is in the molecule's structure: It contains two carbon atoms joined by a high- energy triple bond, with a hydrogen atom capping each end of the molecule. When the triple bond is attacked and broken by oxygen atoms, a very large amount of energy is released. Because of its extremely high energy content, acetylene is also one of the most explosive gasses. Even a small amount, if it explodes, can create a shock wave intense enough to kill a person and flames hot enough to inflict severe burns.
A prize-winning essay about acetylene
How dangerous is it?
More Cool Facts about fire
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