|
|
|
EARTH, OCEANS & SEAS
Our Earth is one of nine
planets in the solar system. It is the only planet known as the “home”
of human beings. Scientists say that our planet Earth is
4.6 billion years
old.
About 71 % of Earth’s surface is covered by water, which is essential to
life. The rest 29% is land, mostly in the form of continents that rise
above the oceans. There are seven major land masses on the earth. Each
area is called a
continent.
The largest continent is
Asia.
The second largest
is
Africa.
North America
comes third and
South
America
fourth. The fifth largest
continent is
Antarctica;
it surrounds the South Pole at the bottom of the world.
Europe is the sixth largest continent and
Australia
is the smallest.
Oceans
and Seas
Why is
the ocean blue?
No one
knows for sure. There are several theories as to why the ocean is usually
blue. Some scientists believe that when sunlight hits seawater, part of
the white light is absorbed and part is reflected. White light is composed
of various shades (all the colours in the rainbow). Seawater does not
absorb blue light, so the blue light is reflected outwards. Some
scientists believe that suspended matter in the sea is responsible for its
blue colour.
|
 An
ocean is a large body of salt water that surrounds a continent.
The planet is
approximately 71% water and contains (5) five oceans, including
the Arctic, Atlantic, Indian, Pacific and Southern. Their
borders are indicated on the world image (above). For many years
only (4) four oceans were officially recognized, and then in the spring
of 2000, the International Hydrographic Organization established the
Southern Ocean, and determined its limits. Those limits include all
water below 60 degrees south, and some of it, like the Arctic Ocean, is
frozen.
(Oceans
by size
approximately)
#1 Pacific (156,000,000 sq km)
#2 Atlantic (76,800,000 sq km)
#3 Indian (68,600,000 sq km)
#4 Southern (20,300,000 sq km)
#5 Arctic (14,000,000 sq km)
|
|
The
world’s Oceans and Continents
 
Why is the ocean water
salty?
It is salty because it
has a lot of salt in it! Salt is a mineral that is found in soil and
rocks, too. Flowing water picks up some salt and carries it to rivers.
Rivers carry it to seas. Since this has been happening for millions of
years, the oceans now have a lot of salt—about one cup per gallon!
Where is the deepest part
of the oceans?
The
deepest place is near the Mariana Islands in the Pacific Ocean. The
water is over 36,000 feet deep in the Mariana Trench. That's over
7 miles deep. Mount Everest is only 6 miles high!
The Planet Earth
Surface Area of the Planet (510,066,000 sq km)
Land Area on the Planet (148,647,000 sq km) 29.1%
Ocean Area (335,258,000 sq km)
Total Water Area
(361,419,000 sq km) 70.9%
Type of Water (97% salt), (3% fresh)
|
|
What is a sea?
Around the edge of the
oceans there are places where the water is shallower, these are known as
seas. We can say
that a body of salt water that is surrounded by land on all or most
sides, or that is part of one of the oceans is called a sea.
For example, the Mediterranean Sea, the Red Sea, the North Sea and the
Arabian Sea.
What is seashore?
The land affected by the
action of the sea, such as cliffs, beaches and mudflats.
Is the Red Sea really
red?
Red Sea is not really
red. Parts of Red Sea look red. In summer millions of tiny red plants
called algae grow in the water, so the water looks red.
Deepest Oceans and Seas
Pacific Ocean
Atlantic Ocean
Indian Ocean
Southern Ocean
Arctic Ocean
Mediterranean Sea
Caribbean Sea
South China Sea
Bering Sea
|
F
How old is our planet Earth?
F
What is meant by a continent?
F
Name all continents according to size
F
Which continent is sixth in size?
F
What is an ocean?
F
Name all oceans according to size
F
Which ocean is third in size? |
F
Why is the ocean water salty?
F
Where is the deepest part of the ocean?
F
What is a sea?
F
What is seashore?
F
Why does
Red
Sea look red in summer?
F
What is the percentage of the land area on planet Earth?
F
Why is the ocean blue? |
|
|
