Unit 5: THE SOLAR SYSTEM 1.THE SOLAR SYSTEM What is a planetary system?

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1 1.THE SOLAR SYSTEM 1.1. What is a planetary system? A planetary system cnsists f the varius nn-stellar bjects rbiting a star such as planets, dwarf planets, mns, asterids, meterids, cmets, and interstellar dust Our Slar System The Slar System is ur Planetary System. The Slar System is abut five billin years ld. It is an exciting place made up f a star we call the Sun, and celestial bdies, such as planets, dwarf planets, mns r satellites, asterids, cmets, and many ther smaller bdies. The Slar System is made up f all the planets that rbit ur Sun. In additin t planets, the Slar System als cnsists f mns, cmets, asterids, dwarf planets, and dust and gas. Figure 1. The Slar System 1 st ESO 5.1

2 1.3. Cmpnents f ur Slar System The Sun. It is a medium-sized star. It is the nly star in ur Slar System. The Sun cntains arund 98% f all the material in the Slar System. It is cmpsed f apprximately 75% hydrgen, 25% helium and small percentages f xygen, carbn, irn and ther elements. The surface temperature f the Sun can reach 5500ºC. But the temperature in the slar nucleus (where nuclear fusin ccurs) is much higher, arund ºC. Figure 2. The Sun The celestial bdies (including ther planets, dwarf planets, mns, asterids, meterids, cmets, and interstellar dust) rbit the Sun. The Sun gives heat and light t the celestial bdies. The Planets. They are celestial bdies revlving arund a star. In ur Slar System there are eight planets which travel arund the Sun in a different rbit. In its rbit, there are nt many ther bjects like the planet. The planets rbits are ellipticals. The fur smaller inner planets: Mercury, Venus, Earth and Mars, als called the terrestrial planets, are primarily cmpsed f rck and metal. Figure 3. The inner planets. The fur uter planets, Jupiter, Saturn, Uranus and Neptune, als called the gas giants, are cmpsed largely f gases and are bigger than the terrestrials. Figure 4. The uter planets. Planets that are clser t the Sun revlve faster than thse that are farther away frm the Sun. 1 st ESO 5.2

3 Dwarf Planet. It is smaller than a planet and in its rbit there are many similar bjects. There are many dwarf planets in ur Slar System. The mst knwn is Plut, which is smaller than ne f Neptune's mns (Tritn). Others dwarf planets are Ceres and Eris. Figure 5. Frm left t right are the dwarf planets Ceres, Plut, and Eris. Mns r satellites. They are celestial bdies which rbit a planet. Earth has ne natural satellite called the Mn. There are many f them, such as Phbs and Deims (Mars mns). Figure 6.The mn. Asterids. They are rck and metal bdies f varied dimensins. They are gruped in tw large belts: the asterid belt and the Kuiper belt. The asterid belt which is lcated between the rbits f the planets Mars and Jupiter. The Kuiper belt which is lcated beynd the rbit f Neptune. Figure 7a.The asterid belt. Figure 7b.Tw asterids. 1 st ESO 5.3

4 Cmets. A cmet is cmpsed f dust and rck particles mixed with frzen water, methane, and ammnia. In ur Slar System there are many cmets which rbit arund the Sun. They release gas cluds when they are near the sun. There are tw types f cmets: Figure 8.A cmet. Shrt-perid cmets: they are riginated in the Kuiper belt and travel arund the Sun. The Halley cmet is the mst famus f this type f cmets and can currently be seen frm the Earth every 75 years. Lng-perid cmets: they are riginated in the Ort Clud and their travel arund the Sun are lnger than the shrt-perid cmets. The Ort Clud. There is mre t ur Slar System beynd the Kuiper Belt. The Ort Clud is a huge spherical clud that surrunds the entire system. It hlds millins f small pieces f ice and rck that slwly rbit the Sun. Billins f cmets surrund the slar system in the Ort Clud. Figure 9.The Ort clud. 1 st ESO 5.4

5 VOCABULARY English Prnunciatin Spanish Asterid ['æstərɔ:ɪd] Asteride Asterids belt ['æstərɔ:ɪd] / [belt] Cinturón de asterides Celestial bdy [] / ['bɒdɪ] Cuerp celeste Cmet ['kɒmɪt] Cmeta Dwarf planet [dwɔ:f] / ['plænɪt] Planeta enan Earth [ɜ:ɵ] Tierra Galaxy ['gæləksɪ] Galaxia Heat [hɪ:t] Calr Jupiter ['dʒʊ:pɪtər] Júpiter Kuiper belt [] / [belt] Cinturón de Kuiper Light [laɪt] Luz Mars [mɑ:z] Marte Mercury ['mɜ:kjʊrɪ] Mercuri Milky Way ['mɪlkɪ] / [weɪ] Vía Láctea Mn [mʊ:n] Luna Neptune ['neptjʊ:n] Neptun Ort Clud [] / [klaʊd] Nube de Ort Orbit ['ɔ:bɪt] Órbita Planet ['plænɪt] Planeta Planetary System ['plænɪtəri] / ['sɪstəm] Sistema planetari Plut ['plu:təʊ] Plutón Satellite ['sætəlaɪt] Satélite Saturn ['sætɜ:n] Saturn Slar System ['səʊlər] / ['sɪstəm] Sistema Slar Star [stɑ:r] Estrella Sun [sʌn] Sl Universe ['jʊ:nɪvɜ:s] Univers 1 st ESO 5.5