Unit 1.

1. The Earth.
1.1. The Earth in the Solar System.
1.2. The Earth: a sphere called GEOID.
1.3. The Earth: a habitable planet
1.4. The elements of the Earth.
2. The movements of the Earth
2.1. Rotation
2.2. Revolution
3. Orientation and location
4. The representation of the Earth.
4.1. Cartographic resources
4.2. cartographic projections

1. THE EARTH
1.1. THE EARTH IN THE SOLAR SYSTEM.
The Earth is a planet that is part of the SOLAR
SYSTEM, which was formed about 4600
million years ago and it is located in one of the
arms of the Milky Way.
The SOLAR SYSTEM is a group of Planets,
dwarf planets, satellites and other celestial
bodies that revolve around the Sun.
 Planets: any of the large bodies that revolve
around the Sun (Mercury, Venus, Earth, Mars, Jupiter,
Saturn, Uranus and Neptune).
 Dwarf planets: bodies that share their orbits
around the Sun with other celestial bodies, such
as comets or asteroids (Pluto).
 Satellites: celestial bodies that revolve around
some planet.

The Earth is the fifth largest planet of the Solar System
and the third-closest to the Sun.

1.2. THE EARTH: A SPHERE CALLED GEOID.
The Earth is a sphere, but not a perfect one. Why?
It is flattened at the poles and widened at the Equator.
This shape is called GEOID.

The widest part of the planet is the
equator: an imaginary line that
divides the Earth in two halves called
hemispheres.
a. In Northern Hemisphere (where Spain is located), we can locate the North
Pole, the Arctic Pole and Tropic of Cancer.
b. In Southern Hemisphere, we can locate the South Pole or Tropic of Capricorn.

1.3. THE EARTH: A HABITABLE PLANET.
Earth is the only planet (we know) that can support life.
WHY?
Because of three physical conditions:
o TEMPERATURES: not extremely cold, not extremely hot.
o ATMOSPHERE: a gaseous layer which provides oxygen and
protects us from solar radiation.
o LARGE AMOUNTS OF WATER: three quarters of the planet
is covered by water.

1.4. THE ELEMENTS OF THE EARTH.
Our planet is formed of solid, liquid and gas elements.
They are grouped into three categories:
1. The Atmosphere.
2. The Hydrosphere.
3. The Geosphere.
VIDEO: https://www.youtube.com/watch?v=bXdFBAk6MBM

1. ATMOSPHERE
 The layer that surrounds the Earth. It is formed by a group
of gases, water vapour and tiny (very small) particles in the air.
 Earth´s atmosphere contains: 78.08 % nitrogen, 20.95 % oxygen, 0.93
% argon, 0.038 % carbon dioxide and traces of hydrogen, helium and other
"noble" gases.

 It is divided into five layers:
1. Troposphere
2. Stratosphere
3. Mesosphere
4. Ionosphere
5. Exosphere

2. GEOSPHERE
It is formed by solid elements. It is divided into THREE LAYERS:
o The mantle (manto):
o Is the middle layer.
o We can find melted rock in it
called Magma.
o The core (núcleo):
o Is the deepest layer.
o The Crust (corteza):
o The thinnest layer of the Earth.
o It is made out of solid rock.
o We can see the Sea floors and
the continents that emerge
from the oceans.

3. HYDROSPHERE
o It is total amount of water existent on Earth.
o Most of the water is salty (like oceans and seas).
o The rest is fresh water (like rivers, lakes, glaciers and
in groundwater). Most of this fresh water is found in
the ice caps.

2. THE MOVEMENTS OF THE EARTH
 Is the movement of the Earth
Planet on its own axis, once
every 24 hours (one day).
 The Earth rotates on an
imaginary line called the Earth´s
axis, that is tilted (inclined) 23,5º.
 One effect of the Earth´s
rotation: the sequences of days
and nights.
2.1. Rotation

Consequences rotation: times zones
TIMES ZONES: as the Earth takes 24 hours to
rotate 360°, the Planet has been divided into 24
times zones. Consequently, 15° represents a
difference of one hour .
You have to take into account that the imaginary lines
that divide the Earth into times zones are not always
straight (there can be territorial, political or commercial
reasons).

How can you calculate the times zones?
 In order to know the time somewhere in the world is
taken as reference the Meridian 0 (or Prime Meridian
or Greenwich Meridian).
 From it, is added one hour for each time zone if we are
moving to the east and subtract one hour for each
time zone if we are moving to the west.
 Let´s practice!!!!! Activity 7, page 11.

2.2. Revolution
• Is the movement of the Planet around the Sun.
• It takes 365 days and 6 hours to complete one revolution (solar year).
• A calendar year is 365 days, so we accumulate the 6 hours and every 4
years we add one day to the month of February = 29 days = LEAP YEAR.
• The consequence: the changing of the seasons:
• Spring: begins with the spring equinox (21-22 March).
• Summer: begins with the summer solstice (21-22 June).
• Autumn: begins with the autumn equinox (22-23 September).
• Winter: begins with the winter solstice (21-22 December).
You have to take into
account that the
seasons are the result,
not only of the
revolution of the Earth,
but also because the
Earth´s axis is tilted.

3. ORIENTATION AND LOCATION
3.1. Orientation (to set an address or direction)
We can locate places on the Earth using the four cardinal
points: NORTH, SOUTH, EAST AND WEST.
 The east is the geographical place where the sun rises
 The west is the place where the sun sets.
 North and south signal the direction of the Earth´s axis.

3.2. Location (To locate a specific point on the Earth's surface).
We use a grid of imaginary lines, called:
 PARALLES: lines of latitude (Equator is the parallel at 0º
latitude. Other important parallels are Tropic of Cancer or Tropic
or Capricorn).
 MERIDIANS: lines of longitude (The meridians of reference is
Greenwich Meridian or Prime Meridian).

3.3. Geographic coordinates. Using parallels and meridians,
we can locate with so much precision a specific point on the
Earth.
Parallels and meridians form an imaginary geographical
network, in the form of a grid, which allows us to locate the
exact position of any place in the world.

 Latitude (N-S): is the angular distance between any point
on the Earth’s surface and the Equator.
 Longitude (E-W): is the angular distance between any
point on the Earth´s surface and the Prime Meridian.
 How to locate an specific point on Earth:
 Firstly, you have to indicate if a place is on the north or south part
of Earth (lines of latitude).
 Secondly, you have to indicate if a place is on the east or west part
of Earth (lines longitude).

4. THE REPRESENTATION OF THE EARTH
 We use maps to represent geographical space. A map
is the graphical representation of an Earth's place on a
flat surface.

 Cartographic projections: we need to use projection systems to
represent the Earth on maps as accurately as possible.
 Main projection system:
 Conic projection – mainly used to represent temperate and
polar regions.
 Plane projection – mainly used to represent the polar regions.
 Cylindrical projection - mainly used to represent the whole
planet, although it may be deficient in the equatorial and
polar areas (Mercator, s. XVI, and Peters, s.XIX).
Peters Mercator

Types of maps
Physical maps: they show geographical
coordinates (parallels and meridians) and
landforms. Different colours are used to
represent altitude.
Thematic maps, such
as political maps,
weather maps and
demographic maps.

Unit 1.

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Unit 1.