Download Unit 5: THE SOLAR SYSTEM 1.THE SOLAR SYSTEM

BIOLOGY &
GEOLOGY
Unit 5: THE SOLAR SYSTEM
1.THE SOLAR SYSTEM
1.1. What is a planetary system?
A planetary system consists of the various non-stellar objects orbiting a star such as
planets, dwarf planets, moons, asteroids, meteoroids, comets, and interstellar dust.
1.2. Our Solar System
The Solar System is our Planetary System. The Solar System is about five billion years
old. It is an exciting place made up of a star we call the Sun, and celestial bodies, such as
planets, dwarf planets, moons or satellites, asteroids, comets, and many other smaller bodies.
The Solar System is made up of all the planets that orbit our Sun. In addition to
planets, the Solar System also consists of moons, comets, asteroids, dwarf
planets, and dust and gas.
Figure 1. The Solar System
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Unit 5: THE SOLAR SYSTEM
1.3. Components of our Solar System
The Sun. It is a medium-sized star. It is the only star in our
Solar System. The Sun contains around 98% of all the material in
the Solar System. It is composed of approximately 75% hydrogen,
25% helium and small percentages of oxygen, carbon, iron and other
elements.
The surface temperature of the Sun can reach 5500ºC. But
the temperature in the solar nucleus (where nuclear fusion occurs)
is much higher, around 15 000 000ºC.
Figure 2. The Sun
The celestial bodies (including other planets, dwarf planets, moons, asteroids,
meteoroids, comets, and interstellar dust) orbit the Sun. The Sun gives heat and light to the
celestial bodies.
The Planets. They are celestial bodies revolving around a star. In our Solar System
there are eight planets which travel around the Sun in a different orbit. In its orbit, there
are not many other objects like the planet.
The planets’ orbits are ellipticals.
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The four smaller inner planets: Mercury, Venus, Earth and Mars, also called the
terrestrial planets, are primarily composed of rock and metal.
Figure 3. The inner planets.
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The four outer planets, Jupiter, Saturn, Uranus and Neptune, also called the
gas giants, are composed largely of gases and are bigger than the terrestrials.
Figure 4. The outer planets.
Planets that are closer to the Sun revolve faster than those that
are farther away from the Sun.
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Unit 5: THE SOLAR SYSTEM
Dwarf Planet. It is smaller than a planet and in its orbit there are many similar
objects. There are many dwarf planets in our Solar System. The most known is Pluto, which is
smaller than one of Neptune's moons (Triton). Others dwarf planets are Ceres and Eris.
Figure 5. From left to right are the
dwarf planets Ceres, Pluto, and Eris.
Moons or satellites. They are celestial bodies which orbit a planet. Earth has one
natural satellite called the Moon. There are many of them, such as Phobos and Deimos (Mars
moons).
Figure 6.The moon.
Asteroids. They are rock and metal bodies of varied dimensions. They are grouped in
two large belts: the asteroid belt and the Kuiper belt.
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The asteroid belt which is located between the orbits of the planets Mars and
Jupiter.
The Kuiper belt which is located beyond the orbit of Neptune.
Figure 7a.The asteroid belt.
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Figure 7b.Two asteroids.
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Unit 5: THE SOLAR SYSTEM
Comets. A comet is composed of dust and rock
particles mixed with frozen water, methane, and
ammonia. In our Solar System there are many comets
which orbit around the Sun. They release gas clouds
when they are near the sun. There are two types of
comets:
Figure 8.A comet.
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Short-period comets: they are originated in the Kuiper belt and travel around
the Sun. The Halley comet is the most famous of this type of comets and can
currently be seen from the Earth every 75 years.
Long-period comets: they are originated in the Oort Cloud and their travel
around the Sun are longer than the short-period comets.
The Oort Cloud. There is more to our Solar System beyond the Kuiper Belt. The Oort
Cloud is a huge spherical cloud that surrounds the entire
system. It holds millions of small pieces of ice and rock
that slowly orbit the Sun.
Billions of comets surround the solar
system in the Oort Cloud.
Figure 9.The Oort cloud.
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Unit 5: THE SOLAR SYSTEM
VOCABULARY
English
Pronunciation
Spanish
Asteroid
['æstərɔ:ɪd]
Asteroide
Asteroids belt
['æstərɔ:ɪd] / [belt]
Cinturón de asteroides
Celestial body
[] / ['bɒdɪ]
Cuerpo celeste
Comet
['kɒmɪt]
Cometa
Dwarf planet
[dwɔ:f] / ['plænɪt]
Planeta enano
Earth
[ɜ:ɵ]
Tierra
Galaxy
['gæləksɪ]
Galaxia
Heat
[hɪ:t]
Calor
Jupiter
['dʒʊ:pɪtər]
Júpiter
Kuiper belt
[] / [belt]
Cinturón de Kuiper
Light
[laɪt]
Luz
Mars
[mɑ:z]
Marte
Mercury
['mɜ:kjʊrɪ]
Mercurio
Milky Way
['mɪlkɪ] / [weɪ]
Vía Láctea
Moon
[mʊ:n]
Luna
Neptune
['neptjʊ:n]
Neptuno
Oort Cloud
[] / [klaʊd]
Nube de Oort
Orbit
['ɔ:bɪt]
Órbita
Planet
['plænɪt]
Planeta
Planetary System
['plænɪtəri] / ['sɪstəm]
Sistema planetario
Pluto
['plu:təʊ]
Plutón
Satellite
['sætəlaɪt]
Satélite
Saturn
['sætɜ:n]
Saturno
Solar System
['səʊlər] / ['sɪstəm]
Sistema Solar
Star
[stɑ:r]
Estrella
Sun
[sʌn]
Sol
Universe
['jʊ:nɪvɜ:s]
Universo
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