Fact When were false teeth first made? The Etruscans in Italy were the first people known to build and
use false teeth. As early as 700 BC they were constructing ivory or bone
teeth, secured with bridgework made out of gold, good enough to eat with.
Such sophisticated work was not seen again until the 1800s. In the 1700s
false teeth were secured to any remaining original teeth or held in place
by spring-loaded mechanisms. The latter sometimes resulted in embarrassing
accidents, as sets of teeth might suddenly pop out, springing into the
air. Such cumbersome dentures had to be removed during eating, since they
were not designed for chewing. Today crowns (false teeth cemented to existing
teeth) and dentures are far more comfortable and practical. It is even
possible to implant artificial teeth directly into the jaw. More about
the history of dentistry: http://www.smiledoc.com/smiledoc/dentist/denhis.html How does Africa make Florida dusty? Because of the strong, persistent trade winds that blow across the
equatorial Atlantic Ocean, each year millions of tons of reddish-brown
dust from Africa settle over Florida, sometimes forming a thin coating
on cars and other surfaces. These fine dust particles make it hard for
some Florida cities to meet federal clean air standards. The dust is swept
up from the Sahara Desert during storms. It can rise as high as 15,000
feet (4,600 meters) before it gets carried out to sea. While the clouds
of dust cross the Atlantic Ocean, most of the large particles fall out
and sink into the water. But the smallest remain aloft, sometimes causing
hazy skies and health problems for Floridians. Dust from Africa also affects
the Caribbean region: http://www.usatoday.com/weather/walm3.htm Dust can
be swept up from China and dropped in California: http://daac.gsfc.nasa.gov/CAMPAIGN_DOCS/OCDST/asian_dust.html What organism has the smallest number of genes? A bacterium of the genus Mycoplasma has the smallest number of genes
of any known self-reproducing organism. (Some viruses have fewer genes,
but they need to use another cell's DNA machinery to reproduce.) Mycoplasma's
DNA was recently sequenced (spelled out in detail). It contains only about
470 genes, meaning that Mycoplasma can make at most only 470 different
kinds of proteins within its cells. Most bacteria can make thousands of
kinds of proteins, and human cells can make hundreds of thousands. Because
Mycoplasma is a parasite, it can steal many important substances from its
host, so it doesn't need to make the proteins that the host uses to make
those substances. Over millions of years, the genes that code for those
proteins have disappeared from its DNA. More about Mycoplasma: http://www.ncgr.org/gsdb/mycoplas.html
http://www.whitman.edu/Departments/Biology/classes/B206/BacterialGenome/MgDisease.html
A complete color map of the genome: http://www.tigr.org/tdb/mdb/mgdb/mgdb_genome_pic/mgdb_pic.html What's the most remote island on Earth? The volcanic island group of Tristan da Cunha is 1,180 miles (1,900
km) from the nearest neighbor, the island of St. Helena. It is in the South
Atlantic Ocean between the southern tips of Africa and South America. There
are five islands in the Tristan da Cunha archipelago, but only the main
island of Tristan is inhabited. The islands are surrounded by deep waters
on all sides. Tristan's highest point is a volcano that erupted in 1961.
Below the volcano is a small but fertile shelf of land, where potatoes
and other crops can be grown. Around the rest of the island, high cliffs
face the sea. Tristan was discovered in 1506 by a Portuguese explorer named
Tristao d'Acunha, but he was not able to land there. Permanent settlement
began in 1810. Fewer than three hundred people live there today, farming
potatoes and catching "crawdads" (rock lobsters) in the waters around the
island. Some people enjoy living on the world's most remote island: http://geowww.gcn.ou.edu/~bweaver/Ascension/tdc.htm
http://www.wndrland.demon.co.uk/tristan_da_cunha/tristan_history.html When did the first flies evolve? The first true flies were Tanyderid crane flies that flew 225 million
years ago. They looked something like today's mosquitoes, and their larvae
lived in swamp mud or wet sand. Crane flies appeared during the Triassic
Period, when the first large dinosaurs were alive. Since then, the true
flies (members of the order Diptera) have evolved into over 100,000 different
species, on every continent except Antarctica. Flies are the most widespread
insects on the planet. Today, the most primitive crane flies are quite
rare, but other kinds of crane flies that evolved more recently are more
common. Maybe you have seen them attracted to lights at night, like huge
mosquitoes with extremely long legs. More about the very first flies: http://www2.sel.barc.usda.gov/Diptera/tanyder.htm
Crane flies make good fishing bait, according to these fishermen: http://www.troutunlimited.org/cranfly.htm
http://fly-fish.com/cranefly.html Previous Cool Facts about flies: http://www.cool-fact.com/archive/1998/09/01.html
http://www.cool-fact.com/archive/1999/01/20.html http://www.cool-fact.com/archive/1998/07/21.html How long are your blood vessels? If you could stretch out all of a human's blood vessels, they would
be more than long enough to go around the world twice. There are over 62,000
miles (99,800 kilometers) of veins, arteries, and capillaries inside of
each of us. The thickest are as thick as a forefinger, while the thinnest,
which are called capillaries, are as thin as a hair. By far the largest
part of the total length is the length of the capillaries. Arteries (which
carry blood away from the heart) and veins (which carry blood back to the
heart) are not just simple tubes. Their walls are lined with muscles that
squeeze the blood inside, providing part of the blood pressure (the rest
is provided by the heart). Interactive diagram of an artery and a vein:
http://www.innerbody.com/image/c1.html The physics of blood pressure: http://www.physics.uq.edu.au/ph128/3a.html
Some previous Cool Facts about blood: http://www.cool-fact.com/archive/1997/02/28.html
http://www.cool-fact.com/archive/1998/04/28.html How many stars are there in most star systems? Most stars belong to double (binary) or multiple systems, in which
two, three, or even more stars orbit around each other. Orbital periods
range from hours to centuries, depending on the masses of the stars and
distances between them. The closest-orbiting binaries are called contact
binaries. In these very fast-orbiting pairs, the two stars actually touch.
Each member of a contact binary system is shaped like a pear, with the
small end touching the other star. They may actually exchange mass at the
point of contact. There are many multiple star systems with four, five,
or even more members. Clusters of stars exist, numbering in the tens or
hundreds, and there are also much larger "globular clusters," which can
contain hundreds of thousands of stars. More about binary and multiple
stars: http://www.oma.be/KSB-ORB/D2/index.html http://www.phy.mtu.edu/apod/ap970219.html
http://astrosun.tn.cornell.edu/courses/astro201/binstar.htm A giant globular
cluster containing 300,000 stars: http://antwrp.gsfc.nasa.gov/apod/ap981017.html Which ancient king benefited from "modern" plumbing? The palace of King Minos of Knossos in Crete featured a number of
early plumbing innovations. The palace, built around 1700 BC, had tightly
sealed terra cotta drain pipes, and a large underground sewer system that
discharged into the river Kairatos. Also at the palace were some of the
earliest known bathtubs, made of painted terra cotta. Unlike today's tubs,
these had no drains, and were filled and emptied by hand. The palace was
also home to the first known flushing toilet. It was a private chamber,
walled off by gypsum panels. It was flushed by rainwater, or by cisterns
poured by hand. More about ancient Minoan plumbing: http://www.theplumber.com/crete.html How can matter particles travel faster than light? Very radioactive elements are surrounded by a deep, blue glow when
they are submerged in water. The glow, which is called Cerenkov radiation,
is produced by high-energy, electrically charged particles moving faster
than light. Isn't faster than light travel impossible? The speed of light
in a vacuum is an ultimate limit, but when light travels through a dense
medium like water, it slows down. If a matter particle travels fast enough
in such a medium, it can leave light photons behind. Such a particle leaves
a "wake" of light as it penetrates the medium. The wake is similar to the
shock wave that follows an airplane moving faster than sound. The faster
the particle travels, the sharper (brighter) the wake becomes, and the
smaller the average wavelength of light in the wake. Nuclear reactor cores
show ultraviolet and blue Cerenkov light: http://nova.nuc.umr.edu/~ans/cerenkov.html What kind of crustacean has three eyes? The aquatic crustacean Triops (the name means "three eyes") in the
subclass Branchiopoda has three eyes. It has two ordinary compound eyes,
and between them a third simple eye. This is the nauplius eye, which is
retained from the larval stage. Triops are also known as phyllopods or
tadpole shrimp. Triops is a very ancient life form. Fossils have been found
from the Permian Period, more than 250 million years ago. In those days,
primitive reptiles and amphibians walked on land, but the dinosaurs had
not yet evolved. Triops can be a pest in rice paddies, where the finger-size
creatures dig in the mud. They have a shell-like cover over the front of
the body, as many as 71 pairs of legs, and a forked tail. Closely related
creatures live in vernal ponds near San Francisco: http://www.r1.fws.gov/sfbnwr/tadpole.html
Another Cool Fact about a creature with three eyes: http://www.cool-fact.com/archive/1997/07/21.html How big are most asteroids? Asteroids are rocky or metallic bodies that orbit the sun, mostly
between the orbits of Mars and Jupiter. There are probably more than a
million of them. Most asteroids are smaller than a medium-size city, and
the vast majority are just boulders or pebbles. The largest asteroid is
Ceres, which is at least 580 miles (930 kilometers) across. The mass of
Ceres is just a bit more than 1/100 of the mass of the moon, and probably
about one quarter of the mass of all the asteroids combined. The second
largest asteroid is Pallas, with less than half of the mass of Ceres. Vesta
is the third largest, but is much brighter than Ceres or Pallas. Are asteroids
the smashed debris of an ancient planet, or are they uncombined leftovers
of the time when the planets formed? Closer examination of more asteroids
by upcoming robot missions may help answer the question. More about asteroids:
http://www.ntv.it/nineplanets/asteroids.html http://www.iki.rssi.ru/solar/eng/asteroid.htm
http://nssdc.gsfc.nasa.gov/planetary/planets/asteroidpage.html When were punched cards first used for data storage? The first punched data cards were invented before there were any
computers in the world. They were used in the Jacquard Loom, a weaving
machine invented in 1801 by Joseph-Marie Jacquard. The cards were carried
in linked chains, and they controlled the weaving pattern by influencing
the position of the needles. Small sensing pins detected the presence or
absence of holes in the cards, and determined whether or not a needle would
pick up a thread. On seeing Jacquard's punched card system, the mathematician
Charles Babbage was inspired to use the same principles to design a mechanical
calculating machine, the forerunner of modern computers. More about Jacquard
looms and early mechanical computation: http://www.csc.liv.ac.uk/~ped/teachadmin/histsci/htmlform/lect4.html
A picture of the loom: http://www.ce.vt.edu/evd/Htmls/P415420.html What are the fastest matter particles in the universe? The fastest known matter particles are ultra-high energy cosmic
rays. These are mostly atomic nuclei of various elements, which come zipping
down into the Earth's atmosphere at nearly the speed of light. Cosmic ray
energies are measured in electron volts. One electron volt is the amount
of energy that an electron gains when it moves across an electric field
of one volt. The fastest cosmic rays can carry more than 100,000,000,000,000,000,000
(one hundred quintillion) electron volts of energy. How much energy is
that? Pick up a rock about the size of your fist, and throw it as hard
as you can. This gives the rock roughly the same energy as a single cosmic
ray particle When such a super-particle crashes into the atmosphere, it
explodes into an "air shower" of thousands of less energetic particles.
The air shower can be detected from the ground by the faint light it emits.
Introduction to cosmic rays: http://helios.gsfc.nasa.gov/cosmic.html More
about ultra-high energy cosmic rays: http://www.sciam.com/0197issue/0197swordy.html Why are elephants in Africa being born without tusks? Ivory poachers in Africa have provided a dramatic demonstration
of how evolution works. By killing only those elephants that bear large,
valuable tusks, they have allowed elephants with smaller tusks or none
at all to multiply. A survey conducted in Uganda's Queen Elizabeth National
Park found that up to 30 percent of the elephants had no tusks, up from
one percent in the 1930s, and many of the rest had greatly reduced tusks.
The same trend is happening all over Africa, as a result of selective culling
by poachers. Elephants use their tusks to help them tear apart vegetation,
dig in the ground for important dietary minerals, and to help them compete
for mates. Without tusks, they are forced to rely on other sources for
food and minerals, and their mating process must change. Researchers believe
that the elephant population is on the rise again after years of severe
poaching. The tuskless elephant population is on the rise across Africa:
http://www.gaiabooks.co.uk/environment/elephants_tuskless.html How does the emperor penguin keep its eggs warm? Emperor penguins brood their eggs by holding them on their feet.
The single egg is protected from the Antarctic cold by a fold of loose
skin called the brood patch. Unlike other penguins, emperors brood their
young during the cold, dark winter months. The female lays one egg, passes
it to the male, then travels out to sea, where she feeds for about nine
weeks. Meanwhile, the male stands still and does not eat, weathering temperatures
as low as -65 degrees Fahrenheit (-54 degrees Centigrade). When the female
returns, she takes over, receiving the just-hatched chick from the hungry
male, who goes out to sea. While he is gone, the chick is fed and raised
by the mother penguin. By the time the sea-ice begins to break up, the
penguin chick is ready to fend for itself. Emperors are the largest, deepest-diving
penguins: http://www.nature.ca/notebooks/english/emperor.htm Penguins are
well-adapted for their life in the cold southern seas: http://www.terraquest.com/va/science/penguins/penguins.html
http://octopus.gma.org/surfing/antarctica/penguin.html More Cool Facts
about penguins: http://www.cool-fact.com/archive/1997/08/22.html http://www.cool-fact.com/archive/1997/11/14.html What's the largest uplifted land mass? The Tibetan Plateau of Asia includes over two million square kilometers
(780,000 square miles) of land, with an average elevation of over 5000
meters (16,400 feet), making it the largest uplifted area on Earth. It
is surrounded by some of the highest, most deeply eroded mountain ranges
on the planet. 14 million years ago, the plateau was even higher. It was
formed about 50 million years ago by the collision of what is now India
with the Eurasian continent. That slow, powerful collision pushed up the
Himalayas, and lifted the Tibetan Plateau. Even today, India still moves
north about five centimeters (two inches) each year. The elevation of the
plateau caused massive changes in the planetary climate, including the
annual monsoon pattern, which brings seasonal floods and droughts to southeast
Asia. The geology of the Tibetan Plateau: http://vishnu.glg.nau.edu/people/jhw/Tibet/Plateau.html
More about the diverse ecosystems of the Tibetan Plateau: http://www.igc.apc.org/ei/tpp/nfabout.htm
Another Cool Fact about the slow collision between India and China: http://www.cool-fact.com/archive/1997/11/06.html Why do body joints make popping sounds? Do a deep knee bend, and it's very likely you'll hear popping sounds
coming from your knee joints. There are also popping sounds when you "crack
your knuckles." What causes the popping sounds? Actually, there are two
kinds of sounds. The joints in your fingers are enclosed in capsules that
contain a lubricating fluid. When the joint is moved near the end of its
range, gas that is dissolved in the joint fluid suddenly comes out of solution,
forming a small bubble and making the popping noise. The joint can't be
"popped" again until the gas redissolves. The knee-bending sounds are most
likely made by tendons (fibers that connect muscles and bones) that snap
into new positions when the joint moves under stress. This kind of popping
noise can be repeated many times, because the tendons shift back and forth
as the joint moves. More about popping joints: http://www.sciam.com/askexpert/medicine/medicine11.html What kind of fish eats stony coral? The parrotfish is a reef dweller that takes bites out of rock-hard
corals, and pulverizes the stony material with its hard beak. It swallows
the resulting mixture of coral sand, algae, and living coral polyps. By
breaking off chunks of coral, the parrotfish plays an important role in
the coral reef ecosystem. It removes surface algae, which might otherwise
completely swallow up the reef. The chewed-up coral sand passes through
the fish and is released, to fall in drifts between the reefs. It slowly
dissolves, and becomes available for use by growing corals. Although the
parrotfish chews up living corals, it is no threat to the coral reefs.
However, overfishing of parrotfishes by humans is a threat. In some places,
parrotfish are now protected from fishing, to preserve the ecological balance
of the reefs. More about parrotfish: http://www.usdivers.com/fun_facts/pfish.htm
Another Cool Fact about parrotfish: http://www.cool-fact.com/archive/1997/12/04.html Who designed the first planned cities? The first system of planned public works was invented and described
by the Greek Hippodamus, who redesigned his own city, Miletus, after it
was destroyed by the Persians. Hippodamus divided his cities into three
sections, for religious, administrative, and commercial uses. He believed
that city design was an art, and that mathematical laws of balance and
proportion were important. Hippodamus invented the concept of "city blocks."
Streets were laid out in regular grids for efficiency. His cities had systems
to deliver water and dispose of sewage and garbage. New Greek cities took
on his distinctive look, and existing cities were redesigned and rebuilt.
Later, the Romans embraced and extended his ideas in their own ambitious
public works projects. More about Miletus, one of the first planned cities:
http://fhw.uni-muenster.de/projects/bouleuterion/en/katopsis/miletus_intro.html
Miletus, Priene, and Didyma all showed features of preplanned design: http://www.turkishodyssey.com/places/aegean/aegean4.htm
A Cool Fact about another inventive Greek from Miletus: http://www.cool-fact.com/archive/1999/01/26.html [FLASH] [Toolbox]
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