◄UNIT 3:MAP WORK INTERPRETATIONUNIT 5:THE ORIGIN OF THE EARTH►

UNIT 4:THE UNIVERSE AND THE SOLAR SYSTEM

  • UNIT 4:THE UNIVERSE AND THE SOLAR SYSTEM

    Key unit competency: The student-teacher should be able to establish
                                                     the difference between the universe and the solar

                                                     system and their respective components.

    Introductory activity

    One of the students in senior one moved outside one evening and all of sudden
    saw a running star that disappeared. The moon was fading, being covered by
    dark clouds. He wondered whether there are moons elsewhere and went back to
    bed. In the morning, the sunrise with golden rays replaced the dark and starry night.
    a) Identify the heavenly bodies mentioned in the passage.
    b) Using your experience and the passage above, identify other components

    of the universe not mentioned in (a) above.

    4.1. Definition and components of the Universe
    4.1.1. Definition
    Activity 4.1
    Study the photograph provided below and use it to answer the questions

    that follow:

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    a) Explain what the above photograph represents.
    b) Using the above photograph, explain the meaning of Universe.
    c) Identify the components of the universe.
    The universe refers to all space and everything in it. It contains everything that
    exists, from the smallest particles to the largest structures known. The exact
    size of the universe is not known. Astronomers estimate that it contains about
    100 billion galaxies. Astronomers are people who study bodies in the sky or
    outer space and their behaviours.

    4.1.2. The components of the Universe
    The Universe contains many heavenly bodies, which vary considerably in size
    from the smallest particles like dust to the largest particles like rocks, comets,
    asteroids, moons, dwarf planets, planets, solar systems, stars and galaxies.

    Galaxy:     a galaxy is a group of billions of stars, with gas and dust held together
    by the same gravitational force. The name of the galaxy in which our planet is
    found is Milk way.

    Cluster:     This is a group of stars which are bound together due to gravitation.
    A star: A star is luminous (gives out light) heavenly body that emits its own
    light. Stars have high temperature. The sun is also a star.
    A planet: a planet is a heavenly body that revolves around a star with a constant

    speed and a specific time. E.g. Earth

    Application Activity 4.1
    Study the simple illustration provided below and use it to answer the

    questions that follow:

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    a) Explain why we should love our universe.
    b) Suppose you are asked by your friend, to describe and relate the above

    illustration with the earth, explain what your answers would be.

    4.2. Solar system: sun and planets
    Activity 4.1
    1. Using the knowledge that you have in Geography, explain the
    meaning of solar system and identify the elements or components
    that form it, and share your finding in class.
    2. Using internet, text books and other sources of geographical

    information, research on the characteristics of sun and planets.

    The term solar system is defined as the gravitational bound of the sun and
    the objects that revolve around it. The solar system is therefore made up of
    the following: the sun, planets and their satellites and other heavenly bodies
    such as asteroids, comets, meteorites, meteors, etc.as it can be observed on the

    figure below

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    4.2. Characteristics of different planets and their positions
    The term planet comes from Greek word ”planets” which means “wanderer”
    and it refers to a round celestial (heavenly) body that revolves around the sun.
    Planets are grouped into categories as discussed below:

    Inner (terrestrial) planets of the solar system     share the common
    characteristics with the planet Earth, They are rocky and nearer to the sun. The

    inner planets of the solar system are therefore Mercury, Venus, Earth and Mars.

    Outer (Jovian) planets of the solar system have similar characteristic with
    Jupiter, they contain small amount of rocky materials but much of their mass
    is occupied by gases. The outer planets of the solar system are thus, Jupiter,
    Saturn, Uranus and Neptune.

    Pluto was also known as the ninth planet, but it was demoted to a dwarf planet
    in 2006 and removed from the list of planets because it never developed fully.
    The following are reasons why Pluto was disqualified:
    i) Its size is too small to be classified as a planet.
    ii) It has no uniform revolution around the sun.
    iii) Its revolution is not circular but spherical in nature.
    iv) Its movement is too slow when compared with the rest of the planets of
    our solar system.

    Application Activity 4.2
    1. You are asked to address the geography students from other schools,
    explain what you would tell them about characteristics of the planets
    found in our solar system.
    2. “The earth is the only planet that supports life” Explain why it is so
    and show how you would ensure that it continues supporting flora

    and fauna.

    4.3. Earth: Peculiar elements of the earth
    Activity 4.3
    Examine the illustration below and use it to answer the questions that follow:
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    a) Using the illustration shown above, explain to your friend the
    meaning of Peculiar elements of the earth.
    b) Identify the componets of the earth that form its exterior part shown
    in the illustration.
    c) Discuss ways through which man can protect and conserve the

    peculiar elements of our planet earth.

    The peculiar elements of the earth are outer parts of the earth. They include
    the following:
    1) Hydrosphere or water bodies
    2) Lithosphere or Land and rocks
    3) Atmosphere or Gases

    4) Biosphere or flora and fauna

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    Peculiar elements of the earth
    • Hydrosphere: This stands for all the waters found on the earth surface.
    It covers 71% of the earth’s surface.
    • Biosphere: This is a part of the earth that includes the totality of life
    on the earth (Animals,Plants and Man).
    • Lithosphere: This is the rocky part of the earth.
    • Atmosphere: It is the gaseous part of the earth. It comprises all gases

    that can be found on the earth.

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    4.4. Earth’s movements
    Activity 4.4
    Read the following passage and answer the questions provided.
    Every day the sun rises in the east and sets in the west. This process led
    many people in the past to think that the sun is moving, and the earth
    is fixed. The sun moves around the earth. But with the advancement of
    science and technology, it has been proved that the sun itself is moving
    and the earth is in a continuous motion. Later it has been revealed that
    the sun does not move around the earth, rather the earth moves around
    the sun.

    Using the knowledge and skills acquired in previous studies answer the
    following questions?
    a) How many movements does the earth make?
    b) Identify proof for the earth rotation and revolution.

    c) Describe effects caused by the above movements.

    4.4.1. Rotation of the Earth and Associated Effects
    Rotation of the Earth is defined as the movement of the Earth spinning on its
    own axis. This movement of the Earth on its own axis is in an anticlockwise

    direction. The earth takes 24 hours to complete its rotation.

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    The effects of rotation of the earth
    As the Earth turns around its axis, it affects some processes on the earth’s
    surface. Some effects of the earth rotation are:

    i) Rotation causes day and night.
    Earth’s rotation on its axis creates day and night. The one half of the Earth that
    faces the sun has day time, while the opposite half facing away from the Sun

    has night time.

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    ii) Rising and falling of ocean water (tides)
    During the rotation of the earth, gravitational force of the sun and the moon
    acts on the ocean water to produce tides which may be high or low tides.

    iii) Deflection of wind and ocean current (Coriolis Effect)
    Rotation causes winds to be deflected to the right in the Northern or to the
    left in southern whenever they cross the Equator. This deflection is called the

    Coriolis Effect.

    iv) Time difference between longitudes
    One round of the Earth is completed after turning 360°.
    This implies that, the earth takes 24 hours to complete its rotation.

    Therefore, in one hour the earth covers 150. This is calculated by:

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    12:00+2hours=14:00. The time at Kigali is: 14:00 PM
    To find the local time of an area which is positioned in the west of the
    given longitude, subtraction is used while when the local time to be
    found is positioned east of the given longitude addition is used.

    v) Temperature difference
    Due to the spherical shape of the earth and the position of the sun, the parts of
    the Earth located in the tropical areas between 23.5˚ North and South of Equator,
    get direct sunlight all the year round. Regions located in higher latitudes get
    less rays during the year.

    4.4.2. Revolution of the Earth and Associated Effects
    The revolution is the movement of the earth around the sun. Earth revolves
    around the Sun along an oval-shaped path called an orbit. The earth takes 365

    days and 6 hours to complete one revolution.

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    The Leap year is the year with 366 days which comes every after four years.
    This results from adding 6 hours rotation of each year to make one day after 4
    ordinary years.

    The consequences of the revolution
    i) Determination of seasonal variation
    The earth’s revolution around the sun causes difference in seasons because
    different parts experience differences in temperatures which lead to difference
    in rainfall distribution. Summer is usually associated with much heat and
    brightness and winter with coldness and rain.

    ii) Varying length of day and night at different times of the year
    The revolution of the earth around the sun causes variations in the length day and
    night time over different latitudes. On 21st June when the sun is overhead at the
    tropic of cancer, day time is longer than night time in the northern hemisphere
    and the reverse takes place in the southern hemisphere. On 22ndDecember
    when the sun is overhead at the tropic of Capricorn night time is shorter than
    day time in the southern hemisphere and in the northern hemisphere night

    time is longer than day time.

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    iii) The beginning and end of the year
    The earth revolves around the sun in a continuous way. When the earth
    completes one revolution, it is referred to as one year. And the end of one
    revolution marks the beginning of another revolution; hence the beginning and

    end of the year.

    iv) Changes in altitude of the midday sun
    Earth’s revolution exposes different parts of the earth to the overhead sun
    differently because of the inclination of the earth’s axis. For instance parts
    of the earth beyond the tropics never experience the overhead sun while the
    equator and the tropics experience the overhead sun alternatively during the

    equinoxes and solstices.

    4.5. Other heavenly bodies
    Apart from the celestial bodies discussed above, other bodies include Asteroids,
    Meteorites, Meteoroids, Meteors, Constellations, Comets and UFOs (unidentified

    flying objects).

    Application Activity 4.4
    1. Rusizi is 28 E and the time is 6:00 am. What is the time in a place
    which is located at 60˚W?
    2. What is the longitude of a place X whose local time is 11:00 a.m.
    if the local time at longitude 30 E is 2:00 pm?
    3. Explain why some parts of the earth’s surface are getting hotter

    than others while others are becoming cool and cold.

    End unit Assessment

    1. Study the two photographs shown below.

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    a) Identify the heavenly bodies shown in the two photographs.
    b) Mention and describe the heavenly bodies found in the universe that
    are not shown in the two photographs.
    c) Explain why the areas shown in the two photographs are all found
    on planet earth yet having different habitable conditions.
    d) Draw a program that can enable man to live in harmony with the
    universe and the earth.
    2. Read the story below and use it to answer the questions that follow:
    Recently John and Mary went to visit their uncle in Rubavu. In the
    afternoon of their second day, they were taken by their cousins to visit
    the lake shores. Evening came, and the moonlight was so intense that
    one could pick the smallest thing at that time. Suddenly, they saw water
    extending in a rhythmic manner to the place they had made a camp fire.”
    a) How could you use your knowledge to convince John and her sister
    Mary that what happened was connected to the moon, sun and
    earth’s rotation.
    b) Suppose you want to build near the coastline, explain how the
    knowledge and the skills acquired from the lesson on tides can guide you.

    ◄UNIT 3:MAP WORK INTERPRETATIONUNIT 5:THE ORIGIN OF THE EARTH►