Britannica Student Encyclopedia - 2010

Aeronautics and Space Administration

(NASA) as a test pilot. Seven years later

Armstrong became an astronaut.

On July 16, 1969, Armstrong, Edwin E.

(Buzz) Aldrin, Jr., and Michael Collins

left for the Moon in the Apollo 11

spacecraft. Four days later, Aldrin and

Armstrong landed on the Moon in the

Eagle, a landing vehicle that separated

from the Apollo spacecraft. Armstrong

was the first to step out onto the Moon’s

surface. For more than two hours he and

Aldrin collected samples of Moon soil,

made measurements, and took photographs

before they began their return

trip to Earth.

Armstrong retired from NASA in 1971.

He continued to teach and to work on

committees about the space program.

#More to explore

Moon • Space Exploration

Army

An army is a large, organized group of

soldiers trained to fight other armies or

groups. An army’s main job is usually to

defend its country in times of war. An

army protects the country against

attacks or invasion by enemies. It may

also fight in other parts of the world.

An army is usually one of several major

branches of a country’s armed forces. In

the United States the other major

branches are the Air Force and the Navy

(which includes the Marine Corps).

Armies Today

Modern armies have ranks, or levels of

power. The soldiers who command soldiers

in lower ranks are called officers.

The officers in the highest ranks are the

generals. The generals are in charge of

the army as a whole. Beneath the generals

are the commissioned officers. They

are graduates of special military training

schools. Beneath them are the noncommissioned

officers. These are men and

women who started out as ordinary soldiers

and moved up through the ranks.

The ordinary soldiers, or privates, make

up the lowest ranks of an army.

Neil Armstrong

Soldiers stand in formation at a U.S. Army

post in Hawaii.

BRITANNICA STUDENT ENCYCLOPEDIA Army 189

 

Sometimes people are drafted, or

ordered by their government to join the

army. Drafts are common in times of

war when too few people volunteer. For

example, the United States, Canada, and

the United Kingdom had drafts during

WorldWar II. Today, however, volunteers

make up these countries’ armies.

Some countries, such as China and

Israel, still require most of their citizens

to serve time in the army.

History

The first army was probably organized

in Sumer, a civilization that began more

than 6,000 years ago in the Middle East.

The earliest soldiers fought with swords,

shields, and bows and arrows. They protected

themselves with armor.

Over the centuries, new developments

in warfare changed the way armies

fought. Arabs and Europeans invented

weapons that used gunpowder in the

1300s. Armies began using machine

guns in the 1800s and bombs in the

1900s. Armies continue to develop new

weapons. New technology also has

helped improve communications and

protect soldiers on the battlefield.

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Air Force • Armor • Bomb • Marines

• Navy •War

Artemis

In ancient Greek mythology Artemis

was the goddess of wild animals and

hunting. She was one of the 12 main

gods believed to live on Mount Olympus.

Artemis was associated with the

Roman goddess Diana because they

shared many of the same characteristics.

The cypress tree and wild animals were

sacred to Artemis.

Artemis was the daughter of Zeus, the

chief Greek god, and Leto. Leto was a

China has the

world’s largest

army.

190 Artemis BRITANNICA STUDENT ENCYCLOPEDIA

 

Titan, or one of the giants who once

ruled the world. Artemis was the twin

sister of Apollo, the god of music and

light. Apollo was associated with the

sun, while Artemis was associated with

the moon. Some people believed that

Artemis helped women during childbirth.

Artemis was a protector of animals,

but she also hunted them. Artists

showed Artemis with a deer or with her

hunting dog and silver bow, a weapon

used to shoot arrows.

According to one story, Artemis loved

the giant huntsman Orion and lived

with him in the forest. Eventually, Artemis

became jealous. She thought that

Orion loved another woman. In

revenge, Artemis shot Orion with an

arrow. Orion was placed in the sky after

his death. There he became a constellation

(a group of stars).

#More to explore

Apollo • Greece, Ancient • Mythology

• Zeus

Arthritis

Arthritis is a common medical problem

for older people. Sufferers of arthritis

experience swelling, pain, and redness in

the joints—the places where the bones

meet. Arthritis commonly affects the

spine, hips, knees, and hands. It may

also attack many other parts of the body.

In severe cases, people may find it difficult

or even impossible to move the

joints at all.

Arthritis seems to run in families. People

whose parents or grandparents had

arthritis often get it themselves. Infections

and injuries can cause rarer types

of arthritis.

In most cases, arthritis is a lifelong condition

without a cure. However, aspirin,

ibuprofen, or other drugs may help to

relieve the pain and swelling. Exercise

may help to increase movement. In

some cases doctors may perform surgery.

They can remove unhealthy tissue or

replace severely damaged joints with

ones made of plastic or metal.

#More to explore

Bone • Medicine