UNIT 1. PLANET EARTH

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

2. 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.
This system is form by a group of planets (Mercury, Venus, Earth, Mars, Jupiter,
Saturn, Uranus and Neptune), dwarf planets*, satellites and other celestial bodies
that REVOLVE around the SUN.
*Dwarf Planet: Category created by International Astronomical Union in 2006. A dwarf
planet is a celestial body that: a) orbits the Sun; b) has enough mass to assume a nearly
round shape; c) has not cleared the neighbourhood around its orbit; d) is not a moon.

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

5. 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.

6. 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.

7. 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.

8. 1. ATMOSPHERE
 The layer that surrounds the Earth. It is formed of 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.

9.  It is essential for life and the main meteorological
process happens there.
 It is divided into five layers:
1. Troposphere
2. Stratosphere
3. Mesosphere
4. Ionosphere
5. Exosphere

10.  Troposphere
 0-12 Km
 The main meteorological phenomena happen here.
 It is the closest layer to Earth's surface.
 It is the layer we live in.
 higher altitude=colder temps
 Stratosphere
 12-50 km.
 Ozone layer is here. It destroys part of the ultraviolet
radiation from the sun.
 Higher altitude=warmer temps.

11.  Mesosphere:
 50-100 km
 Where meteors and comets are destroyed
 higher altitude=colder temps
 Ionosphere or thermosphere:
 85-600 km
 It has practical importance because, among other functions,
it influences radio propagation to distant places on the
Earth.
 Borealis auroras are here.
 Higher altitude=warmer temps.
 Exosphere:
 600-10.000 km.
 Where satellites orbit Earth.

12. 2. GEOSPHERE
It is formed by solid elements. It includes most of the
planet. It is divided into THREE LAYERS:
- The CRUST
- The MANTLE
- The CORE

13.  The Crust (corteza):
 The largest and thinnest layer of the Earth.
 It is made out of solid rock.
What can we see in this layer?
 Sea floors and the continents that emerge from the
oceans.
 The mantle (manto):
 Is the middle layer.
 We can find melted rock in it called Magma.
 The core (núcleo):
 Is the deepest layer.
 It is though to be made of heavy minerals that appear in
a viscous state in its outer and a solid state in its inner
section.

14. 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.

15. 2. THE MOVEMENTS OF THE EARTH
The Earth moves through space in two different ways:
1. Rotation (rotación).
2. Revolution (traslación).
NOW, IT IS YOUR TIME TO LEARN ALONE.
IN ORDER TO LEARN THE MOVEMENTS OF THE EARTH,
YOU WILL HAVE TO DO A WEBQUETS CALLED:
“THE MOVEMENTS OF THE EARTH”.
http://webquest.carm.es/majwq/wq/ver/105558
COME ON!!! YOU CAN DO A GOOD JOB!!!!!

16. Rotation
 Is one of the movements of the Earth.
 The Earth rotates on its own axis.
 It takes 24 hours (23 hours, 56 minutes, 4 seconds) to complete one full
rotation.
 One effect of the Earth´s rotation: the sequences or succession of
days and nights.
 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). In the next slide you have and example of times zones (but not the real
situation because, as you know, the imaginary lines are not always straight).

17. EXERCISE TO PRACTISE THE TIMES ZONES
In Madrid, it is 8 p.m.
What is the time in London, in Madagascar, Egypt and Buenos Aires?

18. The real map of the times zones

19. 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.

20. Revolution
The revolution of the Earth is its elliptical orbit around the Sun.
It takes the Earth one year to orbit the Sun. Exactly, 365 days, 5 hours, 48
minutes and 45 seconds (solar year).
This movement has an important consequence: the changing of the
seasons (summer, autumn, winter and spring).
You have to take into account that the seasons are the result, not only of
the revolution of the Earth, but also of the tilt of the Earth´s axis (23 °).

21. 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 while
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 altitude (Equator is the parallel at 0º
latitude. Other important parallels are Tropic of Cancer or
Tropic or Capricorn )
 MERIDIANS: lines of longitude (all meridians have the same
longitude. The meridians of reference is Greenwich Meridian
or Prime Meridian).

23. 3.3. Geographic coordinates (to define a specific
point on the Earth using degrees). With geographic
coordinates (latitude-longitude) we can locate with a
lot of precision a specific point on the Earth.
 Latitude (North-South): is the angular distance
between any point on the Earth’s surface and the
Equator.
 Longitude (East-West): is the angular distance
between any point on the Earth´s surface and the
Prime Meridian.

25. 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 resources: such as photo interpretation

26.  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 (image pag.17 book).
 Plane projection – mainly used to represent the polar regions
(image pag. 17 book).
 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

27. Types of maps
Topographic maps: they are a detail
description of a place or region. The places
with the same height are linked with lines
called level curves. The closer the level
curves are, the steeper the incline in that
area.
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.

28. THE END
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PLEASE ASK IT ME.