MHE_Rdg_Wonders_LvRdr_G6_On-Level_U5W4_24.pdf

Expository Textby Bill NagelkerkePAIREDREADThe WatchersLookingLookingFurtherFurther The Hubble TelescopeProgram:CR 14Component:LRG6 U5 W4 OPDFVendor:Learning MediaLevel:60CV_CR14_LR_G6_U5W4L60_O_119207.indd 3CV_CR14_LR_G6_U5W4L60_O_119207.indd 324/02/12 3:52 PM24/02/12 3:52 PMSTRATEGIES&SKILLSAPhotography Credit:NASA,ESA,and G.Bacon(STScI)*The total word count is based on words in the running text and headings only.Numerals and words in captions,labels,diagrams,charts,and sidebars are not included.ComprehensionStrategy:RereadSkill:SequenceVocabulary StrategyContext CluesVocabularycolleagues,conservatively,deduction,droned,galaxies,sustain,ultimately,verifyContent StandardsScienceEarth and Space ScienceWord Count:2,651*Program:CR 14Component:LRG6 U5 W4 OPDFVendor:Learning MediaLevel:60Copyright The McGraw-Hill Companies,Inc.All rights reserved.No part of this publication may be reproduced or distributed in any form or by any means,or stored in a database or retrieval system,without the prior written consent of The McGraw-Hill Companies,Inc.,including,but not limited to,network storage or transmission,or broadcast for distance learning.Send all inquiries to:McGraw-Hill EducationTwo Penn PlazaNew York,New York 10121ISBN:978-0-02-119207-6MHID:0-02-119207-3Printed in the United States.1 2 3 4 5 6 7 8 9 DOC 15 14 13 12 11 10IFCIBC_CR14_LR_G6_U5W4L60_O_119207.indd 2IFCIBC_CR14_LR_G6_U5W4L60_O_119207.indd 224/02/12 3:53 PM24/02/12 3:53 PMPAIREDREADIntroduction .2Chapter 1Land or Sky?.4Chapter 2The Amazing Hubble.8Chapter 3Hubbles Last Days.12Conclusion.17Respond to Reading.18The Watchers .19 Glossary.22Index.23 Focus on Science.24Essential QuestionHow does technology lead to discoveries?LookingLookingFurtherFurther The Hubble Telescopeby Bill NagelkerkeProgram:CR 14Component:LRG6 U5 W4 OPDFVendor:Learning MediaLevel:60NASA,ESA,S.Beckwith(STScI)and the HUDF Team 001-009_CR14_LR_G6_U5W4L60_O_119207.indd 1001-009_CR14_LR_G6_U5W4L60_O_119207.indd 124/02/12 4:00 PM24/02/12 4:00 PMLO RESIntroductionIntroductionThrough his telescope,Galileo discovered sunspots and Jupiters moons.The two parts of the word telescope come from the Greek language,and they tell you a lot about what this tool does.Tele means“far”or“a long way”;scope means“to see.”So telescope means“far-seeing.”It is a tool that helps you see things that are far away.Before telescopes were invented,people had to explore the night sky with the naked eye.An ancient Greek named Aristarchus seems to have been the first person to suggest that Earth orbited the sun.Was it just a clever guess?Maybe he watched the night sky so closely that he was certain of his deduction,even without the technology to verify it.By 1609,the Italian scientist Galileo had this technology.He had specially designed a refracting telescope to study the sky.Refracting telescopes bend,or refract,light through a glass lens,and this magnifies distant objects.One of Galileos telescopes made objects appear up to 20 times larger.Program:CR 14Component:LRG6 U5 W4 OPDFVendor:Learning MediaLevel:602(t)NASA,ESA,S.Beckwith(STScI)and the HUDF Team,(b)National Geographic Society/Corbis001-009_CR14_LR_G6_U5W4L60_O_119207.indd 2001-009_CR14_LR_G6_U5W4L60_O_119207.indd 224/02/12 4:00 PM24/02/12 4:00 PMHubble is a joint project between the space agencies of the United States and Europe.Several decades later,the English astronomer Isaac Newton made a reflecting telescope.A reflecting telescope uses mirrors instead of lenses to capture light rays.Other people improved on these two types of telescopes.In 1672,a French inventor named Laurent Cassegrain made a reflecting telescope using two curved mirrors instead of one.The Hubble Space Telescope is a form of this kind of telescope.Hubble has enabled astronomers to see deeper into space and to discover galaxies never seen before.It has helped scientists solve some of the puzzles of the universe,while also creating new ones.Unlike Galileo,todays astronomers dont need to look through telescopes to make observations.Instead,they look at images recorded by cameras and other electronic devices within the telescopes.This is the way the Hubble telescope works.Program:CR 14Component:LRG6 U5 W4 OPDFVendor:Learning MediaLevel:603NASA-STScI 001-009_CR14_LR_G6_U5W4L60_O_119207.indd 3001-009_CR14_LR_G6_U5W4L60_O_119207.indd 324/02/12 4:00 PM24/02/12 4:00 PMWhen Galileo observed the moon through his telescope,he found that it was covered with craters,and wasnt smooth,as people had thought.It was becoming clear that exploring the universe with telescopes would uncover a lot of new knowledge.Astronomers were discovering that the universe was larger and much more complex than anyone had realized.Land-based telescopes became bigger and better.In 1873,the Alvan Clark company completed a refracting telescope that was,at the time,the largest one in the world.It helped astronomers make many important discoveries.For example,in 1877,the telescope enabled Asaph Hall to discover the two moons that orbit Mars.The first permanent mountaintop observatory was the Lick Observatory in California.Its refracting telescope was the worlds largest until 1897.Thats when the Yerkes Observatory in Wisconsin opened.More than 100 years later,Yerkes still boasts the worlds largest refractor,at 40 inches.Chapter 1Land or Sky?Land or Sky?Through his telescope,Galileo was able to see the craters on the moon.Program:CR 14Component:LRG6 U5 W4 OPDFVendor:Learning MediaLevel:604(t)NASA,ESA,S.Beckwith(STScI)and the HUDF Team,(b)StockTrek/Getty Images001-009_CR14_LR_G6_U5W4L60_O_119207.indd 4001-009_CR14_LR_G6_U5W4L60_O_119207.indd 424/02/12 4:00 PM24/02/12 4:00 PMThe most successful OAO was called Copernicus.The problem with land-based optical telescopes is that they are limited in what they can see out in space.A German rocket scientist named Hermann Oberth had an idea.He thought that launching a telescope into space by rocket could help scientists see further into the universe.This idea became reality in 1966.Between 1966 and 1972,four satellites carrying telescopes were sent into space.They were called Orbiting Astronomical Observatories(OAOs).Optical and Radio TelescopesOptical and radio telescopes are two kinds of telescopes.Optical telescopes capture visible light,such as the light from the stars.The Hubble telescope is one of the best-known examples of an optical telescope.Radio telescopes use radio waves to create images.R adio waves,which are invisible,can come from objects such as stars or galaxies.Program:CR 14Component:LRG6 U5 W4 OPDFVendor:Learning MediaLevel:605NASA001-009_CR14_LR_G6_U5W4L60_O_119207.indd 5001-009_CR14_LR_G6_U5W4L60_O_119207.indd 524/02/12 4:00 PM24/02/12 4:00 PM The OAOs ultimately paved the way for other orbiting telescopes.In 1977,the United States government agreed to the building of the Hubble Space Telescope.Thirteen years later,in 1990,it was carried into space by the space shuttle Discovery.The Hubble Space Telescope(also known as HST,or simply Hubble)was named after a famous American astronomer,Edwin Hubble.Hubble now orbits 353 miles(568 kilometers)above Earth.The pictures it takes are some of the clearest images ever seen of celestial objects.The space shuttle Discovery blasts off,taking Hubble into orbit.Hubble has solar panels that harness sunlight to power its instruments.solar panels The Hubble Space TelescopepThe space shuttleeaswemppThh ttle hasanels that s sunlight er its ments.solar pProgram:CR 14Component:LRG6 U5 W4 OPDFVendor:Learning MediaLevel:606NASA,Illustration:Carlos Aon001-009_CR14_LR_G6_U5W4L60_O_119207.indd 6001-009_CR14_LR_G6_U5W4L60_O_119207.indd 624/02/12 4:00 PM24/02/12 4:00 PMAt first,though,things did not go according to plan with the Hubble telescope.After its launch,scientists discovered a problem with the telescopes main mirror and solar panels.These problems were not fixed until 1993 when NASA sent the shuttle Endeavour on a repair mission.Endeavours astronauts installed additional lenses to fix the problem with the mirror.The solar panels were also replaced.The shuttle mission was a great success because it showed that,with regular servicing from Earth,Hubble could have a long life.High above Earths atmosphere,Hubble was able to“see”what other telescopes had never seen before.It sent massive amounts of information back to scientists on Earth.Hubble really was an eye in the sky.Edwin HubbleDuring the 1920s,Edwin Hubble worked at the Mount Wilson Observatory in California,where he studied spiral nebulae,which are clouds of dust and gas in space.His observations showed scientists that there were other galaxies beyond our own.On the 1993 mission,astronauts used the space shuttles robotic arm to help repair Hubble.7Program:CR 14Component:LRG6 U5 W4 OPDFVendor:Learning MediaLevel:60NASA-STScI 001-009_CR14_LR_G6_U5W4L60_O_119207.indd 7001-009_CR14_LR_G6_U5W4L60_O_119207.indd 724/02/12 4:00 PM24/02/12 4:00 PMChapter 2The Amazing HubbleThe Amazing HubbleAs well as being an amazing telescope,Hubble can be thought of as a kind of time machine.To understand this,it helps to understand how far away objects in space really are.Some galaxies are so distant that their light takes billions of years to reach our own solar system.At one point,Hubble was looking deep into an area of space that appeared to have nothing much in it.The NASA scientists who control Hubble from Earth left the telescope pointing in this position for ten days.This allowed the telescope to absorb as much light as possible.To the scientists amazement,Hubble sent back pictures that showed thousands of previously unseen galaxies of all sizes.The area is now known as the Hubble Deep Field.Hubble has found many other amazing things.Scientists have used Hubble data to better pinpoint the age of the universe.They believe the evidence shows this is around 14 billion years.They also now believe the universe is expanding at a faster pace,not slowing down,as some had thought.Program:CR 14Component:LRG6 U5 W4 OPDFVendor:Learning MediaLevel:608Hubbles fascinating images have captured the beauty of space.(t)NASA,ESA,S.Beckwith(STScI)and the HUDF Team,(b)NASA,ESA,and M.Livio and the Hubble 20th Anniversary Team(STScI)001-009_CR14_LR_G6_U5W4L60_O_119207.indd 8001-009_CR14_LR_G6_U5W4L60_O_119207.indd 824/02/12 4:00 PM24/02/12 4:00 PMAll of the information gathered by Hubble is sent back to scientists on Earth.Hubble is controlled by scientists at NASAs Goddard Space Flight Center in Greenbelt,Maryland.They send radio messages via satellites to Hubble.These messages tell the telescope where to look and what to look for.The radio signals are picked up by antennae on the telescope.Everything Hubble sees is recorded by its on-board computers.Hubble sends that information back to Earth the same way it receives its instructionsvia satellite.Goddards scientists send the data they receive to the Space Telescope Science Institute(STScI)in Baltimore,Maryland to be interpreted.Then colleagues around the world download the data over the Internet for use in their own research.123456123456DataStarlightHubble Space TelescopeTracking and Data Relay SatelliteGround Station,White Sands,NMGoddard Space Flight Center,Greenbelt,MDSpace Telescope Science Institute,Baltimore,MDCapturing Data from the Stars Program:CR 14Component:LRG6 U5 W4 OPDFVendor:Learning MediaLevel:609Illustration:Carlos Aon001-009_CR14_LR_G6_U5W4L60_O_119207.indd 9001-009_CR14_LR_G6_U5W4L60_O_119207.indd 924/02/12 4:00 PM24/02/12 4:00 PMYoung scientists can also benefit from Hubbles breakthrough discoveries.One way is through the summer astronomy program run by STScI for college students.Students work with institute staff and other researchers to interpret the information Hubble sends and prepare it for release to the public.They also get the chance to hear speakers talk about Hubble and other space and astronomy topics.Although the summer program is for college students,STScI has also set up the Hubble Deep Field Academy Web site for younger students.The academy site gives students a taste of what its like to be at the receiving end of all that Hubble data.It takes them through the process that astronomers use to interpret Hubbles Deep Field images.On the Hubble Deep Field Academy Web site,students get to study Hubble data.Hubble data.10Program:CR 14Component:LRG6 U5 W4 OPDFVendor:Learning MediaLevel:60Ariel Skelley/Blend Images/Getty Images 010-018_CR14_LR_G6_U5W4L60_O_119207.indd 10010-018_CR14_LR_G6_U5W4L60_O_119207.indd 1024/02/12 4:02 PM24/02/12 4:02 PMThis is the deepest Deep Field snapshot yet.Scientists have counted nearly 10,000 galaxies in just this one image.One of the real-world challenges that academy students tackle has to do with distance.Its hard for astronomers to work out distances between Earth and Deep Field objects.The size of an object does not always relate to its distance.Something small may be closer than something large.Astronomers have to try to measure light to help determine distance.A light-year is the distance that light can travel in a year,which is approximately 6 trillion miles.Thats 6 with 12 zeroes after it:6,000,000,000,000!One object in the Deep Field is nearly 12 billion light-years away.It would take the light from this galaxy 12 billion years to travel to Earth.11Program:CR 14Component:LRG6 U5 W4 OPDFVendor:Learning MediaLevel:60NASA,ESA,S.Beckwith(STScI)and the HUDF Team 010-018_CR14_LR_G6_U5W4L60_O_119207.indd 11010-018_CR14_LR_G6_U5W4L60_O_119207.indd 1124/02/12 4:03 PM24/02/12 4:03 PMChapter 3Hubbles Last DaysHubbles Last DaysDuring a maintenance mission,Hubble is taken out of service and locked onto the space shuttle.In 1997,there was a second shuttle mission to Hubble.Astronauts on the space shuttle Discovery installed a camera that could take images of infrared light coming from very distant galaxies.The astronauts also installed a new spectrograph that would help Hubble hunt for black holes.In 1999,Discovery again headed for Hubble.Astronauts replaced all of Hubbles gyroscopes,the mechanisms that allow scientists on Earth to point Hubble in different directions.New gyroscopes had already been installed during the first service mission in 1993.Luckily,Hubble has six gyroscopes in total,and it does not need all of them to be in working condition to still be on target.Clearly,Hubble had been working hard during its first ten years.12Program:CR 14Component:LRG6 U5 W4 OPDFVendor:Learning MediaLevel:60(t)NASA,ESA,S.Beckwith(STScI)and the HUDF Team,(b)NASA010-018_CR14_LR_G6_U5W4L60_O_119207.indd 12010-018_CR14_LR_G6_U5W4L60_O_119207.indd 1224/02/12 4:03 PM24/02/12 4:03 PMThe shuttle Columbia was the next visitor to Hubble,in March 2002.This time another type of camera was put into Hubble.The camera could see more and record better images.It was also much faster at doing this than the previous cameras had been.Hubbles solar panels were replaced again,with smaller versions that could produce more power.The fourth shuttl