The Remains of Tiny Shells

The material we call 'chalk' was formed during the time when dinosaurs lived on Earth. At that time the oceans were rising higher and higher until finally they covered most of the land.

Billions of tiny animals live in those oceans. They were so small you could not have seen them - they were even smaller than the full stop at the end of this sentence. These tiny creatures had shells made from the element calcium. When they died, their shells fell to the bottom of the sea. After thousands of years, there were many layers of shells on the ocean floor.

As more and more of the tiny shells pressed down from the top, those on the bottom became harder and began to stick together. Eventually the shells changed into a mineral called 'calcite', the main ingredient of the rock known as 'limestone'.

Many millions of years passed after the first chalk was made. The Earth's surface changed its shape, and the land and sea developed new coastlines. This left many chalk layers on dry land, both in the middle of continents and by the sea. In the south of England there are chalk cliffs 244 metres high. These are the famous White Cliffs of Dover, and they are almost solid chalk!

If you had a piece of chalk from of those cliffs, you could use it to write on a chalkboard. But the chalk that is used in classrooms is not dug from the cliffs or the ground. It is made in factories by mixing several different materials. Read more! >>>

Astronomy Amazing Facts

>The planet Pluto is so far away from Earth that the beam of torch, travelling at the speed of light, would take about five hours to get there

>Scientist believe that much of the universe may be made of something call 'dark matter'. This hidden mass may be a substance that people have never before encountered.

>Unlike galaxies, constellations are group of stars. People used to imagine connecting the stars to make pictures in the night sky. Most constellations are named after animals ang mythological figures. They still help astronomers and navigators locate certain stars.

>After our own Sun, the nearest star to Earth is Alpha Centauri. It is 4.3 light-years away, or almost 1.3 billion kilometres from Earth

>Scientist have found three planets orbiting the star Upsilon Andromedae, a star much like our Sun. Some think this means there could be life on one of the planets.

>Here's a surprise: not all asteroids are in outer space! Starfish are also called asteroids. The name that these two very different things share means 'starlike'.

>American author Mark Twain, who wrote Tom Sawyer, was born in 1835 on a day when Halley's Comet could be seen in the sky. Just as he predicted, he died when Halley's Comet was again seen in the sky. 1910.

> The Sun's temperature on the surface is about 5,537 to 6,093 degree celcious. That's 100 time hotther that a really hot day on Earth!

>It's not surprising that Mercury was named after the speedy messenger of the fods. The planet travels at an incredible 48 kilometres per second.

>Some scientish think that an unusual positioning of the planets Venus and Jupiter may have been the bright Star of Betlehem reported at the same time of Jesus Christ's birth.

>Since there's no wind or water on the Moon, the astronauts' footprints could still be there in 10 million years.

>The reason Mars appears red is that the planet's soil contains a lot of rusted iron.

>Jupiter has more than 50 known moons and Earth has only 1. But that seems fair because Jupiter is 1,500 times bigger than Earth.

>Saturn is more than ten times the size of Earth. But the planet is so light that it could float on an ocean of water.

>Between Uranus and Saturn lies Chiron, an objects first considered to be an asteroid, then reclassified as a comet. It's name reflects its confused identity: Chiron was a centaur - a half man, half horse iin Greek mythology.

>Neptune has a shorter day than Earth. So why is Neptune's year so much longer than ours?
{Hint: Neptune is the eighth planet from the Sun, and Earth is only the third.}

>It's more than just a little chilly on Neptune. The average temperature is -225 degree celcius. By comparison, Antartice - the coldest place on Earth - has recorded a mere -90 degree celcius at it's coldest.

>Some scientists think it might be possible to travel through black holes to other parts of the universe, assuming you could somehow survive the crushing gravity.

>Other 'female first' in space include Valentina Tereshkova of Russia (formerly the Soviet Union), the very first woman in space (1963), and Mae Jemison, the first African American woman astronaut, aboard the space shuttle Endeavor (1992)

>In order to leave the Earth's gravity and visit a space station, you hace to travel at a speed of 11 kilometres per second.

>Because different planets have different gravities, an astronaut's weigh would change from planet to planet. For example, an astronaut weighing 75 kilos on Earth would weigh only 28 kilos on Mars but 177 kilos on Jupiter.


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Cat's Facts and Trivia

>Both humans and cats have identical regions in the brain responsible for emotion.

>A cat's brain is more similar to a man's brain than that of a dog.

>A cat has more bones than a human; humans have 206, but the cat has 230 (some cites list 245 bones, and state that bones may fuse together as the cat ages).

>Cats have 30 vertebrae (humans have 33 vertebrae during early development; 26 after the sacral and coccygeal regions fuse)

>The cat's clavicle, or collarbone, does not connect with other bones but is buried in the muscles of the shoulder region. This lack of a functioning collarbone allows them to fit through any opening the size of their head.

>The cat has 500 skeletal muscles (humans have 650).

>Cats have 32 muscles that control the outer ear (compared to human's 6 muscles each). A cat can rotate its ears independently 180 degrees, and can turn in the direction of sound 10 times faster than those of the best watchdog.

>Cats' hearing is much more sensitive than humans and dogs.

>Cats' hearing stops at 65 khz (kilohertz); humans' hearing stops at 20 khz.

>A cat sees about 6 times better than a human at night, and needs 1/6 the amount of of light that a human does - it has a layer of extra reflecting cells which absorb light.

>Recent studies have shown that cats can see blue and green. There is disagreement as to whether they can see red.

>A cat's field of vision is about 185 degrees.

>Blue-eyed, pure white cats are frequently deaf.

>It may take as long as 2 weeks for a kitten to be able to hear well. Their eyes usually open between 7 and 10 days, but sometimes it happens in as little as 2 days.

>A cat has approximately 60 to 80 million olfactory cells (a human has between 5 and 20 million).

>Cats have a special scent organ located in the roof of their mouth, called the Jacobson's organ. It analyzes smells - and is the reason why you will sometimes see your cat "sneer" (called the flehmen response or flehming) when they encounter a strong odor.

>A cat has a total of 24 whiskers, 4 rows of whiskers on each side. The upper two rows can move independently of the bottom two rows. A cat uses its whiskers for measuring distances.

>Cats have 30 teeth (12 incisors, 10 premolars, 4 canines, and 4 molars), while dogs have 42. Kittens have baby teeth, which are replaced by permanent teeth around the age of 7 months.

>A cat's jaw has only up and down motion; it does not have any lateral, side to side motion, like dogs and humans. For this reason, don't rely on feeding dry food as a dental care program - cats need to have their teeth cleaned by a vet.

>When a cat drinks, its tongue - which has tiny barbs on it - scoops the liquid up backwards.

>Cats purr at the same frequency as an idling diesel engine, about 26 cycles per second.

>Domestic cats purr both when inhaling and when exhaling.

>The cat's front paw has 5 toes, but the back paws have 4. Some cats are born with as many as 7 front toes and extra back toes (polydactl).

>Cats step with both left legs, then both right legs when they walk or run.

>Cats walk on their toes.

>A domestic cat can sprint at about 31 miles per hour.

>The heaviest cat on record weighed 46 lbs.

>A kitten will typically weigh about 3 ounces at birth. The typical male housecat will weigh between 7 and 9 pounds, slightly less for female housecats.

>Cats take between 20-40 breaths per minute.

>Normal body temperature for a cat is 102 degrees F.

>A cat's normal pulse is 140-240 beats per minute, with an average of 195.

>Cat's urine glows under a black light.

>Cats lose almost as much fluid in the saliva while grooming themselves as they do through urination.

>Almost 10% of a cat's bones are in its tail, and the tail is used to maintain balance.

>The domestic cat is the only species able to hold its tail vertically while walking. You can also learn about your cat's present state of mind by observing the posture of his tail.

>If a cat is frightened, the hair stands up fairly evenly all over the body; when the cat threatens or is ready to attack, the hair stands up only in a narrow band along the spine and tail

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