The document discusses theories about the structure of the universe and provides information about the solar system and Earth. It describes that historically there was a geocentric theory with Earth at the center, but now the heliocentric theory with the Sun at the center is accepted. Galaxies contain stars, nebulae, and star clusters. Our Milky Way galaxy has a nucleus and spiral arms including the Orion Arm where Earth is located. The solar system includes the Sun and objects like planets, dwarf planets, satellites, and comets. Key details are provided about the properties of planets like Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune. The document also discusses the Earth's revolution around the Sun

1. THE EARTH
WITHIN THE
UNIVERSE
Fátima González Ponce

2. Theories about the Universe.
• The geocentric theory: the Earth is in
the centre of the Universe, and the
Sun and the Moon turn around it.
Mean scientist: Aristotle and Ptolomy.
• The heliocentric theory: Sun is in the
centre of the Universe, and the Earth
revolves around it. Mean scientist:
Copernicus, Galileo Galilei and
Kepler.
Nowadays, we know the Sun is in the centre of the Solar
System, but it’s only one of the countless stars and
systems in the Universe.

3. Galaxy contains:
• Stars: large spheres of hydrogen and helium which
release a great amount of energy from nuclear fusion.
• Nebulae: large clouds of dust and gas.
• Star clusters: related stars close to each other.
Milky Way:
Our galaxy is called the Milky Way. It has a
nucleus of older stars, and a disk with arms, which
contains younger stars. We are in the Orion Arm.

4. The Solar System
The Solar System is composed of:
• The Sun: a medium-sized star made up of 75% hydrogen
and 25% helium. Its nucleus reaches at temperatures of
15.000.000 ºC.
• Planets: the rocky planets (Mercury, Venus, Earth, Mars)
and the Gas Giants (Jupiter, Saturn, Uranus, Neptune).
• Dwarf planets: Pluto, Ceres and Eris.
• Satellites
• Comets: they are made up ice, rocks and dust. They can
be short period comets (from Kuiper Belt) or long period
comets (from Oort Cloud).

6. Features of the planets:
• Revolution: orbit around the Sun. All of them have an
orbit approximately in the same plane and in the same
direction (anticlockwise).
• Rotation: most of the planets rotate around an axis
almost perpendicular, except Uranus (its axis is parallel
to the revolution movement) and Venus (it rotates in
clockwise direction).

7. The Planets (Rocky planets)
Mercury Venus The Earth Mars
Characteristic
s
Closest to
the sun
Craters
Similar size and
density to the
Earth.
Its rotation is in
clockwise
direction, the
opposite than
the other ones
Optimal
conditions for
life to develop
Liquid water
Surface
resembles
Earth’s rocky
deserts
Atmosphere No Denser
Composed of
carbon dioxide
and sulphuric
acid
Nitrogen and
oxygen
95% of
carbon
dioxide
Satellites No No The Moon Deimos and
Phobos

8. The planets (Gas giants)
Jupiter Saturn Uranus Neptune
Characteristic
s
Rocky core
Bands of
different
coloured
clouds
Ring system
made of ice,
dust and rocks
Frozen planet
Rotation
perpendicular
to the ecliptic
Size similar to
Uranus
Frozen planet,
but
temperature
inside very hot
Composition Hydrogen and
helium
Hydrogen and
helium
Hydrogen,
helium and
methane
Hydrogen,
helium and
methane
Satellites Four large and
smaller
ones
Seven large
and more
small ones
Five large and
more smaller
ones
The largest is
Triton

9. The Earth-Moon System
Revolution
• Plane of ecliptic: is the plane of the planet’s revolution orbit
around the Sun.
• The Earth’s revolution takes 365’26 days.
•Seasons are caused by the tilt of the Earth’s axis (23’5º). It
produces a different angle in sunrays, changing the sunlight
period and the temperatures depending on howperpendicular the
rays are.
Rotation
• The Earth’s rotation takes 24 hours.
• Its direction is anticlockwise (from west to east, therefore
we see the Sun rising in the east and setting in the west).

10. The changes of the seasons are:
• Vernal equinox (around 21 March): this day both
hemisphere receives the same amount of sunlight, day and
night have
approximately the same length (12 hours)
• Summer solstice (around 21 June): north hemisphere
receives more sunlight and more hours of daylight.
• Autumnal equinox (around 22 September): is exactly the
opposite of spring equinox, but they have the same
characteristics.
• Winter solstice (around 22 December):
northern hemisphere receives less light, daylight hours start to
decrease, and winter begins.

12. The Moon
We always see the same side of the Moon because its
rotation takes the same time than its revolution.
Due to the movement around the Earth, the Moon
reflects the sunlight in its entire surface, or only in a
part. These are the lunar phases: full moon, waxing
moon, new moon and waning moon.

13. ACTIVITIES
ACTIVITY 1
1. Working on a conceptual basis. (Each student must do a conceptual basis
about the studied contents).
ACTIVITY 2
1. Listen and say which theory the speaker is describing. What do we now
know about where our planet is in the universe today?
2. Put the words in order to make questions. Listen and check. Then ask and
answer the questions with a partner.
do/contain/galaxies/What?
does/a planet/ how long/ to revolve/ take/ around/ the sun/ once?

14. 3. Listen and repeat. Then write in the correct order, starting from
the sun
4. Complete the text with the words. Listen and check
Spring Autumn Summer Winter
• _________this day both hemisphere receives the same amount of
sunlight, day and night have approximately the same length (12
hours)
• __________
north hemisphere receives more sunlight and more hours of
daylight.
• __________
is exactly the opposite of spring equinox, but they have the same
characteristics.
•___________
northern hemisphere receives less light, daylight hours start to
decrease, and winter begins.

15. ACTIVITY 3
1. Ask and answer the questions with your group.
• What types of movement do planets have?
• What are comets made of?
• What is the main gas the sun is composed of?
2. Describe a planet to your group. Guess what planet your partner is
describing
3. Explain the following phenomena to your partners
• We can’t see a new moon
• Daytime and night-time