Expository
Text
Looking
Further
The Hubble Telescope
by Bill Nagelkerke
PAIRED
READ
The Watchers
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STRATEGIES & SKILLS
Comprehension
Vocabulary
Strategy: Reread
Skill: Sequence
colleagues, conservatively,
deduction, droned, galaxies,
sustain, ultimately, verify
Vocabulary Strategy
Content Standards
Context Clues
Science
Earth and Space Science
Word Count: 1,792**
Photography 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.
Copyright © 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 Education
Two Penn Plaza
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ISBN: 978-0-02-119200-7
MHID: 0-02-119200-6
Printed in the United States.
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Essential Question
How does technology lead to discoveries?
Looking
Further
The Hubble Telescope
by Bill Nagelkerke
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Chapter 1
Land or Sky? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Chapter 2
The Amazing Hubble . . . . . . . . . . . . . . . . . . . . . . . . . 8
Chapter 3
Hubble’s Last Days . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
NASA, ESA, S. Beckwith (STScI) and the HUDF Team
Respond to Reading . . . . . . . . . . . . . . . . . . . . . . . . 18
PAIRED
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The Watchers . . . . . . . . . . . . . . . . . . . . . 19
Glossary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Focus on Science . . . . . . . . . . . . . . . . . . .24
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Introduction
The two parts of the word telescope come from
the Greek language. Tele means “a long way,” and
scope means “to see.” A telescope helps you see
things that are far away.
An ancient Greek named Aristarchus seems to
have been the first person to suggest that Earth
went around the sun. He lived before telescopes were
invented. He had to study the sky with his naked eye.
He was sure of his deduction, even though he did not
have a telescope to verify it.
By 1609, the Italian scientist Galileo had made
a refracting telescope. He used it to study the sky.
bend, or refract, light
through a glass lens.
This makes faraway
objects look a lot
larger. One of Galileo’s
telescopes could make
objects appear up to
20 times larger.
Through his telescope,
Galileo discovered sunspots
and Jupiter’s moons.
(t) NASA, ESA, S. Beckwith (STScI) and the HUDF Team, (b) National Geographic Society/Corbis
Refracting telescopes
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Several decades later, the English astronomer Isaac
Newton made a reflecting telescope. A reflecting
telescope uses mirrors instead of lenses to capture
light rays.
The Hubble Space Telescope is a type of reflecting
telescope. Hubble has let astronomers see deep into
space and discover galaxies never seen before.
Today astronomers do not need to look through
telescopes the way Galileo did. They look at images
recorded by electronic devices in the telescopes.
NASA-STScI
This is the way the Hubble telescope works.
The United States
and Europe worked
together to create
the Hubble telescope.
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Chapter 1
Land or Sky?
Exploring the universe with telescopes uncovered
vast amounts of new knowledge. For example, when
Galileo looked at the moon through his telescope, he
discovered it was covered in craters. Before this people
thought the moon was smooth.
Over time telescopes became bigger and better.
In 1873, the Alvan Clark company created a telescope
that was the largest telescope in the world. In 1877, it
helped scientists discover that Mars had two moons.
The Lick Observatory in California was built in 1887.
It was the first permanent mountaintop observatory.
In 1897, the Yerkes Observatory
in Wisconsin opened. Yerkes still
has the world’s largest refracting
telescope is 40 inches across.
Through his telescope,
Galileo was able to see
the craters on the moon.
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(t) NASA, ESA, S. Beckwith (STScI) and the HUDF Team, (b) StockTrek/Getty Images
telescope. The lens in this
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Optical telescopes on Earth, however, are limited in
what they can see. A German rocket scientist named
Hermann Oberth had an idea. He wanted to launch a
telescope into space by rocket. He thought this might
be the best way to see even farther into the universe.
Four satellites carrying telescopes were sent into
space between 1966 and 1972. They were called
Optical Astronomical Observatories (OAOs).
Optical and Radio Telescopes
Optical and radio telescopes are
two types of telescopes. Optical
telescopes capture the light we can
see with our eyes. Hubble is an
optical telescope.
NASA
Radio telescopes use radio waves
to create images. Radio waves are
invisible to us. Objects such as stars
and galaxies send out radio waves.
The most
successful OAO
was called
Copernicus.
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These early orbiting telescopes ultimately paved the
way for others. In 1990, the space shuttle Discovery
carried the Hubble Space Telescope into orbit. The
Hubble was named after the famous American
astronomer, Edwin Hubble.
Hubble now orbits 353 miles (568 kilometers) above
Earth. The pictures it takes are some of the clearest
ever seen of celestial objects.
The Hubble Space
p
Telescope
p
Hubble
e has
solar panels
p
that
harness
s sunlight
ss
to power
w
wer
its
instruments.
m
ments.
NASA, Illustration: Carlos Aon
solar panels
The space shuttle
Discovery blasts
off, taking Hubble
into orbit.
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At first things did
not go according to
plan. After Hubble was
launched, scientists
discovered a problem
with its main mirror and
solar panels.
These problems were
not fixed until 1993 when
NASA sent the space
shuttle Endeavour to
repair Hubble.
Astronauts used the
space shuttle’s robotic
arm to repair Hubble.
The Endeavour’s mission
was a great success. It
showed that Hubble could have a long life if it was
regularly serviced.
High above Earth’s atmosphere, Hubble was able
to see what other telescopes had never seen before.
It sent massive amounts
STOP AND CHECK
of information back
Why is it important to have
a telescope in space?
to Earth.
NASA-STScI
Edwin Hubble
Edwin Hubble worked at the Mount Wilson Observatory
in California in the 1920s. He studied spiral nebulae,
which are clouds of dust and gas in space. He went
on to prove that the universe is expanding.
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Chapter 2
Light takes time to travel. Some galaxies are so
far away that their light can take billions of years to
reach us. Scientists believe Hubble’s pictures show us
how things were billions of years ago.
In this sense, the Hubble can be thought of as a
kind of time machine as well as a telescope. It lets
astronomers see into the universe’s past.
At one point, Hubble looked into an area of space
that seemed to have nothing in it. To the scientists’
amazement, Hubble sent back pictures that showed
thousands of new galaxies. The area is now known
as the Hubble Deep Field.
Scientists have used Hubble information to estimate
the age of the universe.
(t) NASA, ESA, S. Beckwith (STScI) and the HUDF Team, (b) NASA, ESA, and M. Livio and the Hubble 20th Anniversary Team (STScI)
The Amazing Hubble
Hubble information helped
them discover that the
universe is expanding faster.
It is not slowing down as
Hubble’s
fascinating images
have captured the
beauty of space.
some had thought.
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NASA scientists in Greenbelt, Maryland control
Hubble. They send radio messages to Hubble via
satellite. Hubble sends information back to Earth the
same way.
Hubble’s information is then sent to the Space
Telescope Science Institute in Baltimore, Maryland to
be studied. The NASA scientists’ colleagues around
the world can then download the information from the
Internet and use it in their own research.
Capturing Data from the Stars
This diagram shows how Hubble sends data to the Space
Telescope Science Institute.
1
2
Data
3
1
Starlight
2 Hubble Space Telescope
6
3 Tracking and Data
Relay Satellite
4 Ground Station, White
Sands, NM
Illustration: Carlos Aon
5
5 Goddard Space Flight
Center, Greenbelt, MD
6 Space Telescope
Science Institute,
Baltimore, MD
4
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Young scientists can benefit from Hubble’s
discoveries as well. College students can work with
Space Telescope Science Institute staff to study Hubble
data. They also can hear expert speakers talk on
space and astronomy topics.
The institute also has the Hubble Deep Field
Academy Web site for younger students. The site takes
young students through the process that astronomers
Ariel Skelley/Blend Images/Getty Images
use to understand Hubble’s Deep Field pictures.
Students can use the Hubble Deep Field
Academy Web site to study Hubble data.
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This is the deepest
Deep Field picture yet.
The academy students learn about the huge
distances involved in the study of space. They also
learn how difficult it is to determine these distances.
Astronomers have to use light-years to measure the
distances between objects in space. A light-year is the
distance that light can travel in a year. This is about
6 trillion (6,000,000,000,000) miles!
One object in the Deep Field is 12 billion light-years
away from Earth. It takes light from this object
NASA, ESA, S. Beckwith (STScI) and the HUDF Team
12 billion years to travel to Earth!
STOP AND CHECK
What are some of the things Hubble
has shown astronomers?
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Chapter 3
Hubble’s Last Days
In 1997, astronauts installed a camera on Hubble
coming from very distant galaxies. Hubble’s original
cameras could not see as far as this. The astronauts
also installed a new spectrograph to help Hubble hunt
for black holes.
In 1999, astronauts replaced Hubble’s six gyroscopes.
Gyroscopes are devices that allow scientists on Earth to
point Hubble in different directions.
(t) NASA, ESA, S. Beckwith (STScI) and the HUDF Team, (b) NASA
that could take images of infrared light. This light was
During a maintenance mission,
Hubble is taken out of service
and attached to the space shuttle.
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In 2002, another type of camera was installed in
Hubble. This camera could see more and record better
images. It was also a lot faster than Hubble’s other
cameras. The astronauts also updated Hubble’s
solar panels.
In 2009, another space shuttle visited Hubble.
On this trip, astronauts updated some of Hubble’s
equipment to help it stay in orbit for as long as
possible. The space shuttle program is now finished,
so no other shuttles will visit Hubble in the future.
Deep Field and Ultra Deep Field
Illustration: Carlos Aon
Hubble Space
Telescope
In 2004, Hubble
sent an image
called Ultra Deep
Field. It showed
about 10,000
galaxies.
Hubble Deep Field (1995)
Hubble Ultra Deep Field (2004)
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Hubble’s one-millionth observation, on July 4, 2011,
was of a planet that scientists call HAT-P-7b.
This illustration is an artist’s impression of the
planet and the star it is orbiting.
Hubble is expected to remain in orbit for a few more
years. If it lasts until 2015, it will have been in orbit for
25 years. This is an impressive performance—especially
when its life in space was conservatively estimated to
be only 15 years!
At some point, however, Hubble’s various parts will
stop working. Eventually it will be guided back to Earth.
Although one day Hubble will no longer be orbiting
Earth, the end of Hubble does not mean the end of
NASA, ESA, and G. Bacon (STScI)
telescopes in space.
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Hubble Facts
• Hubble weighs 24,500 pounds, or as much
as two full-grown elephants.
• Hubble travels around Earth once every
97 minutes at about 5 miles per second.
• Hubble can see ten times more clearly than
the best telescopes on Earth.
• Lining up Hubble to focus on a faraway object
is like shining a light onto a small coin that is
200 miles (320 kilometers) away.
(bkgd) NASA, ESA, S. Beckwith (STScI) and the HUDF Team
• If you could see as well as Hubble can, you
could stand in New York City and see two
fireflies in San Francisco.
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In 2003, NASA launched the Spitzer Space
Telescope. This telescope has discovered planets
outside our solar system. It has also discovered an
extra ring of Saturn.
There are plans for further exploration by orbiting
telescopes. One of these is the James Webb
Space Telescope.
The Webb telescope will carry special cameras and
spectrometers which measure wavelengths of light. A
sunshield the size of a tennis court will protect it from
the sun’s radiation. The Webb telescope’s main job will
be to study the history of the universe.
STOP AND CHECK
Why will the Hubble stop
working eventually?
NASA
Scientists hope
the Webb
telescope will
look back to
the origins of
the universe.
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Conclusion
The Hubble Space Telescope is one of NASA’s most
successful and longest-lasting missions. Now scientists
are planning a new era in space telescopes. The Webb
telescope will have a mirror seven times bigger than
that of Hubble.
Scientists also will continue to study the sky
using land-based radio telescopes. One of these is
the Square Kilometre Array. This telescope will be so
complex that the technology to understand its data
has not been invented yet!
All this means that there is a lot more work
Panoramic Images/Photodisc/Getty Images
ahead for astronomers, as well as many more exciting
discoveries to be made.
The Square Kilometre
Array will have 3,000 radio
telescopes like these
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Summarize
Event
Use details from Looking Further to
summarize what you learned about how
telescopes have led to new discoveries.
Your graphic organizer may help you.
Text Evidence
1. What features tell you that Looking Further is an
expository text? GENRE
2. What steps led to the development of space-based
telescopes? SEQUENCE
3. What is the meaning of the term spiral nebulae on
page 7? What kind of context clue can you find to
help you figure out the meaning? CONTEXT CLUES
4. Write about the development of the telescope from
Galileo’s time to today. Use events from the text to
help you. WRITE ABOUT READING
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Compare Texts
Read a story about how scientists used telescopes to
make an unusual discovery.
The Watchers
They began orbiting the
planet they had named
Elektron—the old Greek
word for amber, a resin
that could create sparks
of electricity.
The atmosphere in the
control room was certainly
thin
electric! Finally they were within
reach of another planet that could sustain human life.
All eyes were fixed on the SK-ope. Its close-up
views were bringing the planet to life. The crew
babbled with excitement. They had survived last night’s
space storm, and their mission was almost complete.
Illustration: Carlos Aon
“Oceans and forests, and clean air for us to breathe.”
“It looks just like Old Earth!”
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“The telescopes weren’t wrong. They’ve found us
the perfect place to live.”
They turned away from the SK-ope, all talking at
once in their delight. But Commander Diaz stayed by
the SK-ope, her lips pursed.
“The data from the deep-space telescope are so
strong,” Diaz thought. They had been searching for
years, and the evidence was just too good to ignore.
And yet … Diaz had the feeling that something was
horribly wrong. She looked more closely at the screen.
Suddenly the fine hairs on the back of her neck rose
as if charged by electricity.
“Shall we take her down, Commander?” asked
Second Officer Nowak.
Diaz hesitated, then nodded. She had no reason not
to give the order—just that odd feeling.
“Everyone prepare for descent,” Nowak instructed.
The engines droned as the ship slowed.
Diaz remained at the SK-ope.
“Commander? You should buckle in,” Nowak said.
Diaz was silent, frozen in front of the screen.
“What is it?” Nowak asked, more urgently now.
Diaz took her seat next to Nowak and strapped
herself in. Her face was pale and set.
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“Can we pull out of our
descent?” she asked.
Nowak shook his head.
“It’s too late,” he said.
“What is it? What did
you see?”
“I saw people,” Diaz
murmured. “They have their
own kind of SK-ope. And they
were looking at me.”
“Who … what … are they?” Nowak breathed.
“They’re Watchers. That’s what they were doing.
Watching me watching them. And waiting.”
She turned the SK-ope to its lowest level. She
would keep the terrifying images from her crew for
as long as she could.
Images of faces. Familiar faces. Nowak’s face, her
own face looking back at her. The watchers looked
exactly like them.
Make Connections
Illustration: Carlos Aon
How did the scientists use technology to discover
the planet Elektron? ESSENTIAL QUESTION
How do Looking Further and The Watchers help you
to understand the value of telescopes as tools for
exploring the universe? TEXT TO TEXT
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Glossary
atmosphere (AT-muh-sfeer) the gases that surround
planets, including Earth (page 7)
black holes (blak HOLS) parts of space with such
strong gravity that not even light can escape,
making them appear black and empty (page 12)
celestial (suh-LES-chuhl) relating to the sky (page 6)
infrared light (in-fruh-RED light) a type of light that
cannot be seen but is given off by objects above a
certain temperature (page 12)
NASA (NA-suh) National Aeronautics and Space
Administration, the U.S. space exploration agency
(page 7)
observatory (uhb-ZUHR-vuh-tor-ee) a place with
equipment to study the sky (page 4)
optical (OP-ti-kuhl) seen with the eye (page 5)
spectrograph (SPEK-truh-graf ) a device that can split
light into its different colors and photograph them
(page 12)
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Index
Aristarchus, 2
Deep Field, 8, 10, 11
Galileo, 2–4
Hubble, Edwin, 6, 7
James Webb Space Telescope, 16, 17
Newton, Isaac, 3
space shuttle, 6, 7, 12, 13
Space Telescope Science Institute, 9, 10
telescopes
– optical, 5
– radio, 5
– reflecting, 3
– refracting, 2, 4
Ultra Deep Field, 13
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Purpose To understand the difference between the two
main types of optical telescopes and their uses
Procedure
You will need poster paper or board, glue,
and markers.
Step 1
With a partner, reread Looking Further. Take notes
about refracting and reflecting telescopes.
Step 2
Use an educational Internet site to add to this
information. Include diagrams that show how
refracting and reflecting telescopes work.
Step 3
Create a poster with information about the history
of each type of telescope. Your diagrams also should
show how each type of telescope works.
Step 4
Present your poster to the class. Be prepared to
answer questions about your work.
Conclusion What did you discover about the two types
of telescopes?
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Literature Circles
Nonfiction
The Topic
What is Looking Further mostly about?
Text Structure
How does the author organize information in
the book? How does this help you understand
how telescopes have changed?
Conclusions
What is the most important thing you learned
in Looking Further?
What do you think might happen in the future
with telescopes and space exploration?
Author’s Purpose
What were the main points the author wanted
the reader to understand?
Make Connections
What other books have you read about
exploration of our universe? How were these
books similar to or different from this one?
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Breakthroughs
Science
GR U • Benchmark 50 • Lexile [t/k]
Grade 6 • Unit 5 Week 4
www.mheonline.com
ISBN-13 978-0-02-119200-7
MHID 0-02-119200-6
99701
EAN
9 780021 192007
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