of planting a bomb on a U.S.-
owned passenger plane. The bomb killed
270 people over Lockerbie, Scotland, in
1988. The men finally went on trial in
1999. One was found guilty. In 2003
the United Nations lifted a ban it had
placed on trade with Libya.
..More to explore
Arabs • Sahara • Tripoli
The ancient Romans ruled Libya for hundreds
of years. They built theaters and other
structures in Libya more than 1,800 years
ago.
Facts About
LIBYA
Population
(2008 estimate)
5,871,000
Area
679,362 sq mi
(1,759,540 sq
km)
Capital
Tripoli
Form of
government
Socialist state
Major cities
Tripoli, Banghazi,
Misratah, Surt
BRITANNICA STUDENT ENCYCLOPEDIA Libya 145
Lichen
Lichens are made up of two tiny living
things: a fungus and an alga. The
fungus and the alga benefit from living
together. The alga produces food, and
the fungus gathers water. In this way a
lichen can survive harsh weather that
would kill a fungus or an alga growing
alone. This type of relationship is called
symbiosis.
Lichens grow in most parts of the world.
There about 15,000 different species, or
types. Lichens can live where few plants
can survive. They are found in deserts,
near mountain peaks, and in the frozen
Arctic. They grow on stones, tree trunks,
dead wood, and on the ground.
Most lichens are barely 0.25 inch (6
millimeters) high, but some can spread
out to cover several feet. Many lichens
look like flat, crusty blotches. Some look
leafy. Some hang down in strands. Others
have stalks and resemble miniature
forests. Lichens range in color from
brown to bright orange or yellow.
Some kinds of lichen are eaten by reindeer
and even by humans. Other kinds
are used to make dyes, medicines, and
other products.
#More to explore
Algae • Fungus • Symbiosis
Orange lichen covers a boulder
in a mountainous area.
A type of lichen called old-man’s beard grows on a tree trunk in Scotland.
146 Lichen BRITANNICA STUDENT ENCYCLOPEDIA
Liechtenstein
The country of Liechtenstein is one of
the smallest in Europe. Liechtenstein is a
principality, meaning that a prince is the
ruler. Vaduz is the capital.
Geography
The Rhine River separates Liechtenstein
from Switzerland to the west. Austria lies
to the east. Near the Rhine are lowlands.
Mountains cover the eastern part of the
country.
Plants and Animals
Copper beeches, maples, elms, limes,
sycamores, and ashes are common trees
in Liechtenstein. Animal life includes
deer, foxes, badgers, and weasels.
People
Most of the people of Liechtenstein are
related to an old Germanic tribe called
the Alemanni. There are smaller groups
of Swiss, Austrians, and Germans. The
main language is German. Most of the
population is Roman Catholic.
Economy
Banking, tourism, and other services are
important to Liechtenstein’s economy.
Industry is also very important. Factories
produce electronics, ceramics, lenses,
machinery, and metals.
Agriculture is a small part of the
economy. Farmers raise cattle for dairy
products and meat. Crops include
grains, potatoes, and grapes.
History
The Alemanni tribe came into the
region in about AD 500. In 1719 the
Holy Roman Empire combined two
small states into the principality of
Liechtenstein. The country became
independent in 1866. Today the prince
of Liechtenstein plays an active role in
the government.
..More to explore
Holy Roman Empire • Vaduz
The castle of the prince of Liechtenstein
overlooks the town of Vaduz.
Facts About
LIECHTENSTEIN
Population
(2008 estimate)
35,500
Area
62 sq mi (160 sq
km)
Capital
Vaduz
Form of
government
Constitutional
monarchy
Major cities
Schaan, Vaduz
BRITANNICA STUDENT ENCYCLOPEDIA Liechtenstein 147
Light
People and other animals can see
because there is light. Light is a form of
energy. The sun is a very important
source of light energy.Without the
energy from the sun, there would be no
plants or animals on Earth’s surface.
Sources of Light
Besides the sun, other sources provide
light. Burning objects give off light. So
do some animals, such as fireflies and
certain fish. Lightning and electric lightbulbs
also produce light.
Properties of Light
Light exists in two very different forms
at the same time. One form is tiny particles
called photons. The other form is
waves. The easiest way to think about
light is as waves. Light waves travel
through space at a speed of about
186,282 miles per second (299,792 kilometers
per second).
Scientists use an idea called wavelength
to describe light waves. Like waves moving
across a pool of water, light waves
have peaks and valleys. The distance
between two of these peaks is called a
wavelength. Sunlight contains light
waves with long, medium, and short
wavelengths.
The color of light depends on its wavelength.
Red light has the longest wavelength.
Violet light has the shortest
wavelength. Orange, yellow, green, blue,
and indigo have wavelengths in between
those of red and violet. When light
waves of all the colors travel together,
the light looks white.
Certain objects, such as triangular pieces
of glass called prisms, can separate white
light into the individual colors. When
light travels through a prism, waves of
different wavelengths bend by different
amounts. The color of each wavelength
