The Solar System

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_ Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. L 4 _ 8 8 9 4 0 edn setas h oa ytm The System Solar Reading Essentials Planets Dwarf Objects PlanetsandOther Dwarf SystemThe Solar have arockycoresurroundedbythicklayerofice. below locatesCeres,Pluto,andEris.Thesedwarfplanetseach a planet, butnowithasthestatusofadwarfplanet. MAY ah)asdwarfplanets.Plutowasonceconsideredtobe classify Pluto,Ceres,Eris,Makemake,andHaumea(how orbiting nearbyorcrossingitsorbitalpath.Astronomers form asphere.A planet formed,therewasenough dwarf planetasanobjectthatorbitsastar. Whenadwarf shows Pluto anditslargest moon. layer ofice. The imagebelow rocky core surrounded by athick Pluto, Ceres, andEriseachhasa 7 this lesson,reread thestatements to seeifyou have changedyour mind. if you agree withthe statement oraDifyou disagree. After you’ve read whether you agree ordisagree withthem.Place anAintheBefore column What doyou think? . i Rocky n eoeSaeetAfter Statement Before core d d All dwarfplanetsaresmallerthanEarth’s moon.Thefigure The InternationalAstronomicalUnion(IAU)definesa

1 3 Pluto 8. 7. Pluto Ameteoroid isameteor thatstrikesEarth. Asteroids andcomets are mainlyrock andice. dwarf planethasobjectssimilarinmass Charon Ice Readthetwo statements below anddecide mass andgravityforitto Jupiter Neptune Uranus Saturn

1. Interpret margin to useasyou study. and write itsdefinitioninthe you cannot,lookup theword can definethosewords. If read thelessonto seeifyou that you donotknow. Then lesson andunderlinewords Define Words • • • Key Concepts planet orbitsclosestto Earth? form? crater How doesanimpact of comets andasteroids? What are thecharacteristics planet? What isadwarf Visual Check Dysnomia. Eris anditsmoon Telescope This Dysnomia Ceres CHAPTER 21 Hubble Space LESSON 4 Skim Skim the Which dwarf Which dwarf imageshows Eris Eris

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0 1 / 9 1 / Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. 22/19/10 2:37:49 PM is 5 km orbit Comet’s 230°C. Pluto has 230°C. Pluto has - Stardust This image of the nucleus of Wild 2 Wild nucleus of image of the This the by taken was comet far too nucleus was The probe. space coma. a bright have the Sun to from Sun the solar system. Makemake and Haumea, named dwarf planets in 2008,Makemake and Haumea, named of rock and ice that never Recall that asteroids are chunks Comets are mixtures of particles of rock, ice, and dust. Ceres is the smallest dwarf planet. It orbits the Sun in the in the the Sun It orbits planet. dwarf smallest is the Ceres It is so far the size of the Moon. Pluto is about two-thirds in 2003. dwarf planet. It was discovered Eris is the largest Coma Makemake is one of the largest objects in the Kuiper belt. Makemake is one of the largest Most asteroids orbit the clumped together to form a planet. belt is between the orbitsSun in the asteroid belt. The asteroid There are hundreds of thousands of of Mars and Jupiter. Some astronomersasteroids. Pallas is the largest asteroid. suggest that asteroids are very old objects left over from the formation of three known moons: Charon, Hydra, and Nix. Charon Charon, Hydra, and Nix. three known moons: largest moon. Pluto’s to complete one orbit around Eris takes about 557 Earth years uh) is the only known the Sun. Dysnomia (dis NOH mee moon of Eris. region of the solar system.orbit in the Kuiper (KI puhr) belt asteroid belt. It might have a rocky core. A thin, dusty crust A thin, dusty a rocky core. belt. It might have asteroid the core. ice that surrounds layer of water covers a 248 Earth its period of revolution is about from the Sun that covered with of Pluto is so cold that it is years. The surface Its average temperature is frozen nitrogen. Comets Asteroids Eris and Haumea Makemake Ceres Pluto The particles’ gravity holds them loosely together. As shown The particles’ gravity holds them loosely together. Sun in stretched-out elliptical orbits. comets orbit the below, Dust tail Some comets have tails Some have comets than 100 million more long. kilometers Gas tail Coma Gas tail 4 1

In the figure, In the figure,

Where do the do the Where d d n i . Which dwarf 7 0 4

Meteoroids 9 Comets 8 Asteroids Dwarf Planets 8 Key Concept Check Concept Key _ 4 Reading Check L Visual Check Visual _ Solar System The Reading Essentials E Dust tail R _ 6 gas tail. The coma surrounds the surrounds coma The gas tail. nucleus. comet’s The visible parts The are of a comet and the the dust tail, the coma, planet is the largest? Which planet is the largest? dwarf planet is the smallest? 376 4. Identify orbits of most asteroids orbits of most asteroids occur? 3. Specify 2. State 2. State highlight the comet’s highlight the comet’s elliptical orbit. organize your notes on other on other notes your organize objectsin the solar system. Make a layered book to book to Makea layered 1 0 _ 3 1 0 _ 4 9 1 CC194_013_016_RE_L4_889407.indd 14 CC194_013_016_RE_L4_889407.indd 15 1 9 4 _ 0 1 3 _ 0 1 6 _ R E

_ Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. L 4 _ 8 8 9 4 0 or amoon 170 impactcraters. ofameteorite by theimpact object depression ofaplanet,moon,orotherspace formedonthesurface forms abowl-shapedimpactcrater. called ameteorite. up completely. Whenthishappens,themeteoroidisthen large enoughthattheyreachEarth’s surfacebefore theyburn Most meteoroidsburnupinEarth’s atmosphere.Someare is astreak oflightinEarth’s atmosphere madeby aglowing meteoroid meteoroid andtheairaroundithotenoughtoglow. atmosphere, itcreatesfriction.Thefrictionmakesthe as a grain ofsand.AsameteoroidpassesthroughEarth’s moves through space edn setas h oa ytm The System Solar Reading Essentials Meteoroids Short-Period andLong-Period Comets The ofComets Structure atmosphere every day.atmosphere every millions ofyearstoorbittheSun. 100,000 AUfromtheSun.Somelong-periodcometstake Oort cloudsurroundsthesolarsystemandextendsabout outer edgeofthesolarsystemcalledOortcloud.The orbit theSun.Long-periodcometscomefromanareaat Neptune toabout50AUfromtheSun. Kuiper b orbit theSun.Mostshort-periodcometscomefrom away fromtheSun. tail—a dusttailandagastail.Thealwayspoints gas anddustinthecomet’s nucleus,itcancreateatwo-part the comet’s nucleus.WhenenergyfromtheSunstrikes tail andglowingnucleus,calledacoma.Thecomasurrounds nucleus andmakesitglow. Thisproducesthecomet’s bright pushes someof the gasanddustawayfromcomet’s change theiceincometintoagas.EnergyfromSun moves closertotheSun,itgetshotter. Highertemperatures 7 . i n d d When alargemeteorite A long-periodcomettakesmorethan200Earthyearsto A short-periodcomettakeslessthan200Earthyearsto The solid,innerpartofacometisitsnucleus.As Millions ofparticlescalledmeteoroidsenterEarth’s

1 5 elt. TheKuiperbeltextendsfrom about theorbitof . . Mostmeteoroidsareonlyaboutasbig A

meteorite A

meteoroid strikes amoonorplanet,itoften . Earth’s surfacehasmorethan

is ameteoroid thatstrikes aplanet

is a small, rocky particle that is asmall, particle rocky An

impact craterimpact

is around A

meteor .

it again?Explain. you ever beableto observe long-period comet, would form? crater to causes animpact 6. Apply 5. Describe 7. Summarize characteristics ofacomet. characteristics Key Concept Check Key Concept Check

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END OF LESSON ED . a small, rocky particle that moves through space through particle rocky moves that a small, a meteoroid that strikes a planet or a moon a strikes that a meteoroid onnect C meteor Log on to ConnectED.mcgraw-hill.com ConnectED.mcgraw-hill.com on to Log find this to textbook your and access resources. lesson’s meteorite: meteorite: meteoroid: relates to the term relates to the term meteoroid 6 1

a round depression formed on the surface depression of a round

d d n i . 7 0 some names more than once. 4 a streak of light in Earth’s atmosphere made by made by atmosphere in Earth’s of light a streak 9 8 8 _ 4 L a glowing a glowing meteoroid a planet, moon, or other space object or other space moon, the impact by planet, of a a meteorite _ Solar System The Reading Essentials names) belt (two Orbits in the Kuiper layer. its ice A thin, dusty crust covers dwarf Largest planet its surface. covers nitrogen Frozen objects belt One of the largest in the Kuiper E Smallest dwarf planet Describe the characteristics of a dwarf planet. Write the name of each dwarf planet next to its description in the chart. You will need to to its description in the chart. You the name of each dwarf planet next Write write Review the terms and their definitions in the Mini Glossary. Write two sentences that two sentences that Write Mini Glossary. and their definitions in the Review the terms term explain how the belt Orbits in the asteroid agree with the statement or a D if you disagree. disagree. or a D if you the statement with agree mind? change your Did you Reread the statements at the beginning of the at the beginning the statements Reread with an A if you column in the After lesson. Fill R What do you think e. f. g. a. b. c. d. Description Dwarf Planet _ 6

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Content Vocabulary LESSON 4 Dwarf Planets and Other Objects Directions: Answer each question on the lines provided. Use complete sentences.

impact crater meteor meteorite meteoroid

1. What is the difference between a meteorite and a meteoroid?

2. How is an impact crater formed?

3. How is a meteor related to a meteoroid?

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Lesson Outline LESSON 4 Dwarf Planets and Other Objects

A. Dwarf Planets 1. A dwarf planet is a sphere that orbits a(n) . 2. A dwarf planet has objects similar in orbiting near it or crossing its orbital path. 3. The dwarf planets in the solar system are , Ceres, Eris, Makemake, and Haumea. a. Ceres is located in the belt. It is the dwarf planet in the solar system. b. Pluto has a rocky core surrounded by . It has known moons. c. is the largest dwarf planet. It is three times farther from the Sun than the dwarf planet is. d. Makemake and Haumea are dwarf planets in the . B. Asteroids 1. Asteroids orbit the Sun in a band between and Jupiter. Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. 2. The largest asteroid is called . 3. Asteroids are chunks of rock and . C. Comets 1. Comets are made up of rocks, ice, and . a. between the particles in a comet holds it together. b. Comets the Sun in long elliptical orbits. 2. As a comet approaches the Sun, a bright can develop on the comet. a. The is the solid, inner part of a comet. b. As the comet approaches the Sun, it heats, changing some ice in the nucleus into a(n) . c. Energy from the Sun pushes gas and dust particles away from the nucleus and makes it .

66 The Solar System

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Lesson Outline continued

3. comets take less than 200 years to orbit the Sun. They usually come from the . 4. comets take more than 200 years to orbit the Sun. They come from the . D. Meteoroids 1. A small, rocky particle that moves through space is a(n) . 2. As it passes through Earth’s atmosphere, friction with the air makes a meteoroid and the air around it . 3. A streak of light in the atmosphere made by a glowing meteoroid is a(n) . 4. Most meteoroids up in the atmosphere. a. A meteoroid that strikes the surface of a planet or a moon is called a(n) . b. A meteorite can form a bowl-shaped depression called a(n) in the surface it strikes. Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. The McGraw-Hill of a division © Glencoe/McGraw-Hill, Copyright

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