Download unit 5 the planet earth

UNIT 5: THE UNIVERSE AND THE EARTH
1. THE EARTH, A PLANET IN THE SOLAR SYSTEM
The Universe is enormous and contains billions of galaxies, stars, planets,
satellites, asteroids and comets. It is thought that the Universe was created
after the Big Bang, circa 14 billions years ago.
The Earth is the only known inhabited planet. It is located in the Solar System,
which belongs to the Milky Way galaxy.
Our closest galaxy is called Andromeda, which is around 2.2 million light-years.
A light -year is the distance covered by light in a year at the speed of 300 000
km per second.
Within the Milky Way there are more than 250 Solar Systems.
A star is a huge ball of gas that gives out light and heat Stars can be different
sizes, colours and temperatures.
Our Solar System was created when the big cloud of gas and dust reached
11,000,000ºC, which permitted the formation of a star, the Sun.
In our Solar System there are eight planets and five dwarf planets. They have
different sizes and satellites revolving around.
Planets and satellites are celestial bodies that do not produce their own lights.
Satellites revolve around planets.
Planet
Mercury
Inner
Venus
planets Earth
Mars
Asteroids’ belt
Jupiter
Outer
Saturn
planets Uranus
Neptune
Distance
to
the
sun
(million
km)
58
108
149
228
Diameter
Satellites
(thousand
km)
Orbit’s
period
(years)
Rotation’s
period
(days)
4.8
12.3
12.8
6.9
1
2
0.24
0.72
1
1.88
58.6
243
1
1.03
778
1,428
2,873
4,498
142
120
50.7
48.6
65
62
27
13
11.86
29.46
84.01
164.79
0.414
0.426
0.718
0.675
All the planets of the Solar System revolve around an only star. The orbits on
which they revolve are elliptical.
The inner planets are mostly rocky and small, whereas the outer planets are
gaseous, big and they have many satellites revolving around them.
The Earth’s only satellite is called the Moon.
2. PLANET EARTH
The Earth is not a perfect sphere, because it is slightly flattened at the poles.
Some scientists say its shape is similar to an irregular geometric shape called a
geoid. If you cut our planet in half, it would be divided into two hemispheres of
equal size, the Northern Hemisphere and the Southern Hemisphere.
•
•
The 70% consists of water (oceans, seas, rivers, and lakes). The Southern
Hemisphere is known as the maritime hemisphere because it is mostly
made up of huge oceans.
The 30% consists of land (continents and islands). The most of them are in
the Northern Hemisphere.
Life can exist on the Earth thanks to several factors:
• Mild temperature (around 15ºC average).
• There is liquid water on the surface.
• Our atmosphere contains the vital gases we need (21% oxygen, 78%
nitrogen and 1% of other gases). It avoids excessive cooling and heating of
the Earth and it filters the harmful solar radiations (UVA Rays and X Rays).
Without the atmosphere it would be impossible the life on the Earth.
3. THE MOVEMENTS OF THE EARTH
The Earth has two kinds of movements:
• Earth’s orbit around the sun (revolution movement). Our planet moves at
30 km/sec following its elliptical orbit around the sun, which takes 365 days
and 6 hours (that explains the leap years every four years, which have 366
days). It provokes the seasonal change due to the axial tilt.
• Rotation. The Earth spins on its own
axis, which takes 24 hours:
It moves from west to east. Therefore
day and night are caused by the rotation
since the sun just lights half of the Earth.
4. PARTS OF THE EARTH
It is said that the Earth is composed by three different layers: the Atmosphere,
the Hydrosphere and the Lithosphere.
•
-
Atmosphere. It has several layers:
Troposphere (<15 km).
Stratosphere (15-50 km). It contains
the ozone layer (25-40 km), which
protects us from any radiations.
Mesosphere (50-85 km).
Thermosphere (50-600 km).
Exosphere (600-10,000 km)
.
•
•
Hydrosphere. It is composed of
seas, rivers, lakes, ice, and
subterranean waters. It is more
than 70% of the world. There are
five oceans in the world: Atlantic,
Pacific, Indian, Arctic
and
Antarctic Oceans.
Lithosphere. It is composed of continents and the seabed. There are six
continents in the world: Asia, America, Africa, Europe, Oceania and
Antarctica.
5. REPRESENTATION OF THE EARTH: MAPS
The way to represent the Earth has changed in the history. Until the 15th
century it was thought that it was flat. Christopher Columbus and other
explorers proved that it was not such. Scientists helped measure the Earth and
represent it. That was the origin of the cartography, the science in charge of
representing the Earth.
There are several ways to represent the Earth:
•
It can be done through a terrestrial globe. It
is the best way to represent the Earth
because it is a three-dimensional scale
model of the Earth. The main problem is that
it cannot have many details.
•
The most common way to
represent the Earth is
through maps. They are
two-dimensional
scale
models of the Earth. They
are done basing on
mathematical
formulas
called projections, which
adapt the geoidal shape of
the Earth into a plan.
There are several kinds of projections that depend on what we want to
represent better, the most common ones are:
•
Cylindrical projection. It represents
the whole planet, taking the equator
as its centre, so the farther the
regions are from the equator the
more distorted they are. The most
known cylindrical projection is called
Mercator, after its cartographer.
•
Conic projection. It represents
high latitudes and the poles. The
result is a map with semi-circular
parallels and radial meridians.
Distortion is minimal at the point
where the cone intersects the globe
but increases as we move away
from that point.
•
Azimuthal or planar projection. It just
represents one hemisphere. The pole
is the centre of the projection. That fact
explains that the farther the region is
from the pole the more distorted it is.
Maps are an essential tool for studying the surface of our planet. A map is a
two-dimensional representation of the Earth’s surface. It has been reduced in
size and shows information in a simplified, selective and conventional way.
There are several kinds of maps:
• Topographic maps are general maps
that show physical features (natural:
relief, rivers…) and man-made features
(artificial: cities, roads, crops…).
•
-
Thematic maps show information about a particular theme connected with
a specific area. The most common thematic maps are:
Climatic. They show information about different climates such temperature
and precipitation.
Political. They show political boundaries and administrative divisions of
countries, cities and towns.
Economic. These maps summarise information about activities such as
agriculture, industry and tourism.
-
Demographic. These maps show information about the population, for
example, population density and migration.
6. GEOGRAPHICAL COORDINATES
There are several major elements on a map or on a terrestrial globe:
• Cardinal Points. They help the orientation and can be known thanks to
nature or to other artificial means, such as the compass: North, South,
East and West.
•
Coordinates. They help find an exact point on a map through imaginary
lines. The units taken for that measure are degrees (º), minutes (’), and
seconds (’’).
•
Meridians. They are the imaginary lines that link the poles (they go from the
north to the south or vice versa). They fix the longitude, which can be either
east or west. All the meridians measure the same and there are 360 (up to
180ºE and 180ºW).
In 1884 it was agreed to fix the location of the Prime Meridian (0º) in
Greenwich, hence its name. It has its antipodes at 180º.
Meridians fix the time zones, which are 24 in total basing on the location of
each region and the sun (each time zone stretches 15º). The time we use as
a reference is called Greenwich Mean Time (GMT). As we move eastwards,
clocks move forward the same number of hours as time zones travelled. On
the contrary, if we move westwards, clocks go back the same number of
hours as time zones travelled.
•
Parallels. They are imaginary lines that are parallel to the equator (parallel
0º). There are 180 in total (90ºN and 90ºS). They fix the latitude (north or
south) and divide the world into two parts, the northern and the southern
hemispheres. There are several major parallels.
-
-
Equator. It is located at 0º and it separates the northern and the southern
hemispheres.
Tropics. They are the imaginary lines that are the maximal point of
perpendicular fall of the sun onto the Earth. They are caused due to the axial
tilt.
Tropic of Cancer. It is located at 23º27’N.
Tropic of Capricorn. It is located at 23º27’S.
Polar Circles. They are the imaginary lines above which there is at least 24
hours of day-time or night-time in a row. They are also caused by the axial
tilt.
Arctic Circle. It is located at 66º33’N
Antarctic Circle. It is located at 66º33’S.
EXERCISES
1. What is the Milky Way?
2. How many planets are there in our Solar System? How many dwarf planets are
there?
3. Match the words to the correct groups:
Jupiter
Milky Way
Pluto
planets
Earth
dwarf planets
Ceres
galaxies
Saturn
stars
Sun
Mars
4. Answer true or false and correct the wrong sentences:
a. There are three dwarf planets.
b. The eight planets are divided into three groups.
c. The smallest planet is Venus.
5. Which planet is nearest to the Sun? Which is the furthest from the Sun? What is the
Earth’s position?
6. Which planet is nearest to the Earth? Which is the farthest planet from the Earth?
7. Which is the largest planet of the Solar System? And which is the smallest one?
8. Complete the sentences and choose the correct words:
a. The Earth is a(n) perfect/imperfect___________ sphere.
b.
The
Equator
divides
the
Earth
into
two
equal
poles/
hemispheres_____________.
c. One reason there is life on Earth is because there is liquid
water/gas___________.
d. The temperature/atmosphere_______________ protects us from harmful
radiation.
9. In which hemisphere are most of the Earth’s continents?
10. Look at the picture and answer the following questions:
a. How many cardinal points are there?
b. How can we explain the apparent movement of the Sun?
c. At what cardinal point does the sun rise?
11. What season is it when both hemispheres receive the same amount of light?
12. What season is it in the north when the North Pole is tilted towards the Sun?
13. Make a drawing of the layers of the atmosphere.
14. Which atmospheric layer is being described?
a. Meteorological phenomena happen here.
b. It is where the ozone layer is located.
c. Temperatures are very high in this layer.
d. Most of the air we breathe is located in this layer.
15. How can the atmosphere protect the Earth?
16. Draw a map of the Earth and add the main parallels (Equator, Tropic of Cancer,
Tropic of Capricorn, Arctic Circle, Antarctic Circle), the prime meridian, South Pole
and North Pole.
17. In an atlas locate your town or city and write down what parallel and meridian it is
on.
18. Match each word to one of the two concepts below:
North
Greenwich
Tropic of Cancer
Longitude
parallels
Latitude
meridians
West
Arctic Circle
Time zones
19. In an atlas, find the geographic coordinates (latitude and longitude) of the following
cities.
a. Tokyo.
b. New York.
c. Moscow.
d. Johannesburg.
e. Madrid.
f. Montevideo.
g. Sydney.
20. In an atlas find five countries that the Equator runs through and five that the
Greenwich meridian goes through.
21. Is there any place in the world at latitude 110ºN or 110ºS. If yes, say where it is. If
not, explain why.
22. Only one of these names of parallels and meridians is correct. Write the others
correctly.
a. Tropic of Equator.
b. Circle of Cancer.
c. Arctic Circle.
d. Meridian of Capricorn.
e. Tropic of Greenwich.
23. With the help of an atlas, answer this question. What time is it in the following cities
if in Greenwich it is 4 p.m.?
a. Warsaw.
b. Baghdad.
c. Wellington.
d. Lima.
e. Las Palmas de Gran Canaria.
24. How many time zones are there in the world? How wide is each time zone?
25. Do all places in Spain share the same time?
26. Why is it necessary to use cartographic projections to depict the Earth?
27. What part of the world will be more distorted if we use a cylindrical projection? And
if we use a conical projection?
28. Order the letters to make words from the unit:
a. Mdianeri
b. Lallraep
c. Ltdeitua
d. Itngudelo
e. Uareqto
f. Tpirocs
g. Cphyrtogra
h. Tatiroon
29. Match four of the words from the previous activity to the definitions below:
a. An imaginary circle that divides the Earth into two equal halves.
b. The practice of drawing maps.
c. The distance between any point of the Earth’s surface and the 0º meridian.
d. The 24-hour movement of the Earth.
30. Answer the following questions:
a. What is a map?
b. What are maps used for?
c. How did maps emerge in the past?
31. Which is the best projection to represent...?
a. The poles.
b. The areas in middle latitudes.
c. The world.
32. Find the following cities on the map:
a. Porto Novo (32ºS, 52ºW).
b. Cracow (50ºN, 20ºE).
c. Castellón de la Plana (40ºN, 0ºE).
d. Singapore (0ºN, 104ºE).
e. Miami (30ºN, 80ºW).
33. True or false. Correct the false ones:
a. There are 15 time zones of 24º each.
b. In a cylindrical projection, the Earth is inscribed on a cylinder.
c. It is the same time in all countries of the world.
d. Aerial photography obtains images from artificial satellites.
e. Numerical scale is expressed by fraction in which the numerator represents
the unit on the map and the denominator expresses the real size.
f. On large-scale maps, very large areas of the Earth are represented with very
little detail.
34. Match each term with its definition:
Rotation Longitude Meridian Latitude
a. The distance, measured in degrees, from any point on Earth to the
Greenwich meridian.
b. The movement of the Earth around its axis.
c. The distance, measured in degrees, from any point on Earth to the equator.
d. The imaginary line that goes from the North Pole to the South Pole.
GLOSSARY
Antipodes: antipodas
Asteroid: asteroide
Atmosphere: atmósfera
axial tilt: inclinación del eje
Axis: eje
Boundary: frontera
Cardinal Points: puntos cardinales
Cartography: cartografía
Comet: cometa
Compass: brújula
Coordinates: coordenadas
Crop: cultivo
Degrees: grados
Detail: detalle
Dust: polvo
dwarf planets: planetas enanos
Earth: Tierra
East: este
Eastwards: al este
Elliptical: elíptico
Equator: Ecuador
Features: características
Filter: filtro
Flat: plano
Galaxies: galaxias
Gaseous: gaseoso
Geoid: geoide
Harmful: dañino, nocivo
Hemispheres: Hemisferios
inner planets: planetas interiores
latitude: latitud
layer: capa
leap year: año bisiesto
Longitude: longitud
Measure: medida
Meridian: meridiano
Mild: suave
Milky Way galaxy: galaxia Vía Láctea
Model: modelo, ejemplo
outer planets: planetas exteriores
orbit: órbita
ozone: ozono
Parallels: paralelos
Polar Circles: Círculos polares
Poles:Polos
Projection: Proyección
Radiation: Radiación
Relief: Relieve
Rocky: rocoso
Rotation: rotación
Scale: escala
Seabed: fondo marino
Seasonal: estacional
Several: varios
Shape: forma
Sphere: esfera
Star: estrella
Surface: superficie
Temperature: temperatura
terrestrial globe: globo terrestre
Topographic: topografico
Tropic: trópico
West: oeste
Westwards: hacia el oeste
Whole: entero
To avoid: esquivar, evitar
To belong: pertenecer a
To distort: distorsionar
To increase: aumentar
To protect: proteger
To reach: llegar, alcanzar
To revolve: girar
To spin, spun, spun: hacer girar, rotar
To stretch: estirar
To summarize: resumir
To think, thought, thought: pensar