The size of Moon compared to Earth

If you are making models of the Earth and Moon to show their relative size and mass: the Earth would be a ball of clay 6 inches in diameter (about the size of a large bagel) and the Moon would be a golf ball. The dimples on the golf ball would match the size of the largest lunar craters. (Internet Sources)

Arabic Alphabet

The Arabic alphabet is an offshoot of the early Semitic one, probably originated about the 4th century AD. It has 28 letters and is based on 18 distinct shapes plus dots written above or below those shapes. Arabic is written from right to left, and the letters are joined in writing. It spread to such languages as Persian, Pashto, and Urdu and is generally used by the Islamic world in parts of Asia and Africa, and in southern Europe. Arabic is written in either of two forms: Kufic, a heavy, bold, formal script, was devised at the end of the 7th century; or Naskhi, a cursive form and the parent of modern Arabic writing. (Encarta Encyclopedia)

Number of cells in a human body vs. stars in Milky Way galaxy

The Milky Way is a barred spiral galaxy 100,000–120,000 light-years in diameter containing 200–400 billion stars. The human body … consists of an estimated 20 to 30 trillion cells. This means there are approximately 75 times more cells in a human body than stars in the Milky Way galaxy. Amazing! (Adapted from Wikipedia Encyclopedia and Encarta Encyclopedia)

Our Milky Way Galaxy

The Milky Way is the galaxy that contains the Earth. This name derives from its appearance as a dim "milky" glowing band arching across the night sky, in which the naked eye cannot distinguish individual stars. The Milky Way appears like a band because it is a disk-shaped structure being viewed from inside. The fact that this faint band of light is made up of stars was proven in 1610 when Galileo Galilei used his telescope to resolve it into individual stars. In the 1920s, observations by astronomer Edwin Hubble showed that the Milky Way is just one of many galaxies.

The Milky Way is a barred spiral galaxy 100,000–120,000 light-years in diameter containing 200–400 billion stars. It may contain at least as many planets, with an estimated 10 billion of those orbiting in the habitable zone of their parent stars. The Solar System is located within the disk, around two thirds of the way out from the Galactic Center, on the inner edge of a spiral-shaped concentration of gas and dust called the Orion–Cygnus Arm. The Galaxy rotates differentially, faster towards the center and slower towards the outer edge. The rotational period is about 200 million years at the position of the Sun. The Galaxy as a whole is moving at a velocity of 552 to 630 km per second, depending on the relative frame of reference. It is estimated to be about 13.2 billion years old, nearly as old as the Universe. Surrounded by several smaller satellite galaxies, the Milky Way is part of the Local Group of galaxies, which forms a subcomponent of the Virgo Supercluster. (Adapted from Wikipedia Encyclopedia)

Sources of Vitamin C in the Diet

Sources of Vitamin C in the Diet
Food	mg Vitamin C	% of RDA
raw orange	45	75
raw grapefruit	37	62
raw apple	5.7	10
raw plum	9.8	16
potato, baked	12.8	21
carrot, raw	9.3	16
peas, boiled	47.9	80
tomato, raw	19.1	32
squash, acorn, baked	10.8	18
all data for 100 grams of food % RDA is the percent of the Recommended Daily Allowance suggested by the United States Department of Agriculture

Baboon

Also called dog-faced monkeys, they live in brush, grassland, or rocky country, foraging on the ground for roots, seeds, fruits, insects, and small animals, including other monkeys. Depending on the species, they may gather in troops of 350 individuals or more for protection at sleep sites on rock outcroppings. Baboons are powerful fighters and show little fear of larger animals, including humans. They can successfully take on leopards, their worst enemies. Most species travel in groups of 40 to 80, which are socially based on a core of females and may include several transient males. (Internet Sources)

Cells

Cells are the smallest structures capable of basic life processes, such as taking in nutrients, expelling waste, and reproducing. All living things are composed of cells. Some microscopic organisms, such as bacteria and protozoa, are unicellular, meaning they consist of a single cell. Plants, animals, and fungi are multicellular; that is, they are composed of a great many cells working in concert. But whether it makes up an entire bacterium or is just one of trillions in a human being, the cell is a marvel of design and efficiency. Cells carry out thousands of biochemical reactions each minute and reproduce new cells that perpetuate life.

Cells vary considerably in size. The smallest cell, a type of bacterium known as a mycoplasma, measures 0.0001 mm (0.000004 in) in diameter; 10,000 mycoplasmas in a row are only as wide as the diameter of a human hair. Among the largest cells are the nerve cells that run down a giraffe’s neck; these cells can exceed 3 m (9.7 ft) in length. Human cells also display a variety of sizes, from small red blood cells that measure 0.00076 mm (0.00003 in) to liver cells that may be ten times larger. About 10,000 average-sized human cells can fit on the head of a pin.

Greece

The mountainous country of Greece includes more than 2,000 scattered islands and has one of the largest merchant fleets in the world. (National Geographic)

Atom

Atom is the tiny basic building block of matter. All the material on Earth is composed of various combinations of atoms. Atoms are the smallest particles of a chemical element that still exhibit all the chemical properties unique to that element. A row of 100 million atoms would be only about a centimeter long. Understanding atoms is key to understanding the physical world. More than 100 different elements exist in nature, each with its own unique atomic makeup. The atoms of these elements react with one another and combine in different ways to form a virtually unlimited number of chemical compounds. When two or more atoms combine, they form a molecule. For example, two atoms of the element hydrogen (abbreviated H) combine with one atom of the element oxygen (O) to form a molecule of water (H20). (Encarta Encyclopedia)

Mountains

Mountains make up about one-fifth of the world's landscape, and provide homes to at least one-tenth of the world's people. (Internet sources)

Kinds of Sleep and Types of Dreams

By studying sleeping volunteers, researchers have learned that there are different kinds of sleep. Every night, you go through a number of sleep cycles. Each cycle lasts about 90 minutes and is made up of a period of deep sleep and a period of light sleep. Near the end of the cycle comes a period of what scientists call rapid eye movement , or REM, sleep. During REM sleep, a person's eyes move back and forth as if he or she were watching something. Brain waves show patterns that resemble those seen in a person who is awake. The sleeper's heart and breathing rates may increase. And by waking volunteers during REM sleep, researchers have learned that this is when most dreams occur.

Over eight hours of sleep, most people have three to five dreams, each lasting five to fifty minutes. Usually, most of the dreams are forgotten by morning. But by waking volunteers in the middle of a dream and asking them about it, researchers have learned a lot about dreams. For example, while many people think that they dream in black and white, dreams are almost always in color. Apparently the memory of the colors in our dreams fades even more quickly than the memory of the dreams themselves.

People usually hear as well as see in their dreams. Dreams may even involve the senses of smell and touch. Blind people dream as much as sighted people, but their dreams are made up of sounds, smells, and sensations. During REM sleep, their eyes don't move.

In many dreams, the dreamer simply watches the action. In others the dreamer plays a part. While sleeping, people seldom move or act out their dreams. That's because messages from the brain to the muscles are blocked during REM sleep. (Grolier Book of Knowledge Encyclopedia)

Blood vessels in human body

There are 62,000 miles of blood vessels in the human body – laid end to end they would circle the earth 2.5 times. (Internet Sources)

An apple a day keeps the doctors away!

The apple is one of the world's most popular fruits. Apple trees don't bear their first fruit until they are four or five years old. Apples are known for their wonderful taste as well as high nutritional value. They are a popular low-calorie snack. As apples provides a number of health benefits, it is recommended to eat an apple everyday for good health.

Apples originated in the Middle East about 4000 years ago. They are members of the rose family. They are available year round. More than 7,500 varieties of apples are grown all over the world.  The United States grows about 2,500 varieties of apples. Apples come in different varieties of color such as red, yellow, green, etc.  Apples range in size, from a bit bigger than a cherry to as large as a grapefruit. Some of the most popular varieties of apples are Red Delicious, Golden Delicious, Gala, Fuji, Granny Smith, Rome, Empire, etc. Red Delicious is the most popular and most-produced apple in the United States. Golden Delicious is the second most popular. The only apple native to North America is the crabapple. Half the United States apple crop is turned into apple products like applesauce and apple juice. China produces more apples than any other country. Washington, New York, Michigan, Pennsylvania, and California are the top 5 apple-producing states in the U.S. In all, 36 states produce apples commercially. The apple is the official state fruit of Washington, New York, Rhode Island, and West Virginia.

World’s first postage stamps

The world's first postage stamps were issued in Great Britain in May, 1840. The stamps, known as the Penny Black and the Two-Penny Blue, featured an identical design, a profile of young Queen Victoria. They were made possible by some ideas that we take for granted but were revolutionary back in the 1800's: that postage rates should be uniform and based on weight rather than distance, and that postage should be paid by the sender (rather than the receiver). (The New Book of Knowledge by Grolier)

Blood Types

The four blood types are known as A, B, AB, and O. Blood type A contains red blood cells that have a substance A on their surface. This type of blood also contains an antibody directed against substance B, found on the red cells of persons with blood type B. Type B blood contains the reverse combination. Serum of blood type AB contains neither antibody, but red cells in this type of blood contain both A and B substances. In type O blood, neither substance is present on the red cells, but the individual is capable of forming antibodies directed against red cells containing substance A or B. If blood type A is transfused into a person with B type blood, anti-A antibodies in the recipient will destroy the transfused A red cells. Because O type blood has neither substance on its red cells, it can be given successfully to almost any person. Persons with blood type AB have no antibodies and can receive any of the four types of blood; thus blood types O and AB are called universal donors and universal recipients, respectively. (Encarta Encyclopedia)

Emerald Isle

Ireland is called the Emerald Isle because of its lush green landscape. (National Geographic)

Who made the first kites?

No one knows for sure who made the first kites, but it's believed that they were invented in China more than 2,000 years ago. According to one legend, a farmer got the idea when a gust of wind blew off his hat. The hat had a string that tied under the farmer's chin, so he didn't lose it. But the ability of the wind to carry his hat gave him an idea for a toy with which to amuse himself and his friends. (The New Book of Knowledge by Grolier)

Waves

Waves are the forward movement of the ocean's water due to the oscillation of water particles by the frictional drag of wind over the water's surface. (Internet Sources)

Second largest planet in the solar system

Saturn is the second largest planet in our solar system. It is so big that earth could fit into it 764 times. Although Saturn is much bigger compared to Earth it’s density is so low that makes it the least-dense planet in our solar system. Earth is the densest planet – 8 times as dense as Saturn. (Internet Sources)