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Resources
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Chapter 18
Studying Space
Table of Contents
Section 1 Astronomy: The Original Science
Section 2 Telescopes
Section 3 Mapping the Stars
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Chapter 18
Section 1 The Nine Planets
Bellringer
Choose a planet to research. Create a poster that
features the planet and includes a cross section of the
planet’s interior. Provide factual information and
mythology about the planet on your poster.
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Chapter 18
Section 1 The Nine Planets
Objectives
• List the planets in the order in which they orbit the
sun.
• Explain how scientists measure distances in
space.
• Describe how the planets in our solar system were
discovered.
• Describe three ways in which the inner planets and
outer planets differ.
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Chapter 18
Section 1 Astronomy: The Original
Science
Astronomy
• People in ancient cultures used the seasonal
cycles to determine when they should plant and
harvest crops. They built observatories to study
the night sky.
• Over time, the science of astronomy developed.
Astronomy is the study of the universe.
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Chapter 18
Section 1 Astronomy: The Original
Science
Our Modern Calendar
• What Is Our Calendar Based On? The years,
months, and days of our modern calendar are
based on the observation of bodies in our solar
system.
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Chapter 18
Section 1 Astronomy: The Original
Science
Who’s Who of Early Astronomy
• Ptolemy: An EarthCentered Universe
Ptolemy thought that
the Earth was at the
center of the universe
and that the other
planets and the sun
revolved around the
Earth.
• Ptolemaic theory or
Geocentric theory
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Chapter 18
Section 1 Astronomy: The Original
Science
Who’s Who of Early Astronomy
• Copernicus: A SunCentered Universe
Copernicus thought the
sun is at the center of
the universe, and all of
the planets—including
the Earth—orbit the
sun.
• Copernican theory or the
Heliocentric theory
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Chapter 18
Section 1 Astronomy: The Original
Science
Who’s Who of Early Astronomy, continued
• Tycho Brahe: A Wealth of Data In the late1500s, Danish astronomer Tycho Brahe made
the most detailed astronomical observations that
had ever been recorded.
• Thought the sun and moon revolved around the
Earth, but that all other planets revolved around
the sun
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Chapter 18
Johannes Kepler:
• Used Brahe’s data and theorized that all planets revolve
around the sun in elliptical orbits and that the sun was
not in the exact center
• Laws of Planetary Motion Johannes Kepler stated three
laws of planetary motion. These laws are still used today.
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Chapter 18
Section 1
Galileo Galilei:
One of the first to use simple lenses to make distant
objects seem closer
• His first telescope was 3-powered, and he learned how
use grid lenses to make stronger telescopes
• Discovered that the Earth’s moon had craters, Jupiter
had 4 moons, there were sunspots on the sun, and
Venus had phases
• Considered to be the father of modern astronomy
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Chapter 18
Section 1
Isaac Newton:
• Developed 3 Laws of Motion
• The Law of Inertia, the Law of Universal Gravitation, and
the Law of Action/Reaction
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Chapter 18
Section 1 Astronomy: The Original
Science
Edwin Hubble:
• Edwin Hubble: Beyond the Edge of the Milky Way In
1924, Edwin Hubble proved that other galaxies existed
beyond the edge of the Milky Way.
• Studied the light from stars in distant galaxies using a
spectroscope
• Found that distant galaxies are moving further away from
Earth, the universe is expanding, known as the red shift
• If a star moves away from Earth, the wavelengths expand,
and the light spectrum shifts toward the red end
• If a star moves towards the Earth, the wavelengths
shorten, and the light spectrum shifts toward the blue end
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Chapter 18
Section 2 Telescopes
Bellringer
Have you ever bent or slowed down light? Explain how.
Record your answer in your science journal.
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Chapter 18
Section 2 Telescopes
Objectives
• Compare refracting telescopes with reflecting
telescopes.
• Explain how the atmosphere limits astronomical
observations, and explain how astronomers
overcome these limitations.
• List the types of electromagnetic radiation that
astronomers use to study objects in space.
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Chapter 18
Section 2 Telescopes
Telescopes
• A Telescope is an instrument that gathers
electromagnetic radiation from objects in space
and concentrates it for better observation.
• There are many different types of telescopes:
• Optical: including reflecting and refracting
• Non-Optical: which detect radiation that cannot
be seen by the human eye: such as radio, infared,
ultraviolet, & x-ray telescopes
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Chapter 18
Section 2 Telescopes
Optical Telescopes
• Use a series of mirrors, lenses, or a combination of
the two to magnify the image formed by light.
• Refracting Telescopes Telescopes that use lenses to
gather and focus light are called refracting telescopes.
• Reflecting Telescope A telescope that uses a curved
mirror to gather and focus light is called a reflecting
telescope.
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Chapter 18
Section 2 Telescopes
Optical Telescopes
• Refracting Telescopes Disadvantages:
• Distortion of color which prevents clear images
• Size of objective lense will distort images because
of gravity
• Reflecting Telescope Advantages:
• Mirrors can be large without sacrificing clarity
• Curved mirrors are polished which does not allow
light to enter the glass
• Mirrors focus all colors to a focal point.
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Chapter 18
Section 2 Telescopes
Refracting and Reflecting Telescopes
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Chapter 18
Section 2 Telescopes
Optical Telescopes, continued
• Very Large Reflecting Telescopes In some very
large reflecting telescopes, several mirrors work
together to collect light and focus it in the same
area.
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Chapter 18
Section 2 Telescopes
Optical Telescopes, continued
• Optical Telescopes and the Atmosphere The light
gathered by telescopes on the Earth is affected by the
atmosphere.
• Optical Telescopes in Space To avoid interference by
the atmosphere, scientists have put telescopes in space
•
•
•
•
Blocks most invisible radiation from objects in space
Motion of air above a telescope causes starlight to blur
Moisture in air and thicker air
Light pollution and air pollution
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Chapter 18
Section 2 Telescopes
The Electromagnetic Spectrum
• What Is the Electromagnetic Spectrum? The
electromagnetic spectrum is made up of all of the
wavelengths of electromagnetic radiation.
• Detecting Electromagnetic Radiation Visible
light is only a small band of the electromagnetic
spectrum. Radio waves, microwaves, infrared light,
ultraviolet light, X rays, and gamma rays— are
invisible to the human eye.
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Chapter 18
Section 2 Telescopes
The Electromagnetic Spectrum
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Chapter 18
Section 2 Telescopes
Nonoptical Telescopes
• Radio Telescopes Radio telescopes detect radio
waves. Because radio wavelengths are much larger than
optical wavelengths, radio telescopes must be very large.
• In most radio telescopes, a curved metal dish gathers
and focuses radio waves to an antenna which then
produces an image on a computer
• Does not have to be as flawless as the optical lenses
and mirrors
• Linking Radio Telescopes Astronomers can get more
detailed images of the universe by linking radio
telescopes together. Working together, the telescopes
function as a single giant telescope.
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Chapter 18
Section 2 Telescopes
Nonoptical Telescopes, continued
• Nonoptical Telescopes in Space Because most
electromagnetic waves are blocked by the Earth’s
atmosphere, scientists have placed ultraviolet
telescopes, infrared telescopes, gamma-ray telescopes,
and X-ray telescopes in space.
• Infared Telescopes: must be placed in space because
the water vapor in the Earth’s atmosphere absorbs the
low-energy photons
• UV telescopes: use reflectors as collectors of light, the
Earth’s ozone layer block’s their reception
• X-ray telescopes: least able to pass though the Earth’s
atmosphere
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Chapter 18
Summary
Telescope Summary
Refracting telescopes use lenses
Reflecting telescopes use mirrors
Infrared telescopes use infrared images
UV telescopes use ultraviolet rays
X-ray telescopes use x-rays
Non-optical telescopes are carried by satellites
into space
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Chapter 18
Section 3 Mapping the Stars
Bellringer
Is it possible to determine the direction of the North Pole
just by looking at the stars? Explain your answer.
Write your answer in your science journal.
.
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Chapter 18
Section 3 Mapping the Stars
Objectives
• Explain how constellations are used to organize
the night sky.
• Describe how the altitude of a star is measured.
• Explain how the celestial sphere is used to
describe the location of objects in the sky.
• Compare size and scale in the universe, and
explain how red shift indicates that the universe is
expanding.
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Chapter 18
Section 3 Mapping the Stars
Patterns in the Sky
• Constellations Help Organize the Sky A
constellation is a region of the sky. Each
constellation shares a border with neighboring
constellations. A constellation map is shown on
the next slide.
• Seasonal Changes As Earth revolves around
the sun, the apparent locations of the
constellations change from season to season.
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Chapter 18
Section 4 Moons
Spring Constellations in the Northern Hemisphere
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Chapter 18
Section 3 Mapping the Stars
Finding Stars in the Night Sky
• You can describe the location of a star or planet by
using an instrument called an astrolabe and the
following points of reference:
• The zenith is the point in the sky directly above on
observer on Earth.
• The altitude is the angle between an object in the sky
and the horizon.
• The horizon is the line where the sky and the Earth
appear to meet.
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Chapter 18
Section 4 Moons
Zenith, Altitude, and Horizon
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Chapter 18
Section 3 Mapping the Stars
Finding Stars in the Night Sky, continued
• Using an astrolabe allows you to describe where
a star or planet is relative to you. Scientists need
a different method that describes location
independently of the observer’s location.
• Astronomers describe the location of a star or
planet in terms of the celestial sphere.
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Chapter 18
Section 4 Moons
The Celestial Sphere
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Chapter 18
Section 3 Mapping the Stars
Describing a Star’s Position
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Chapter 18
Section 3 Mapping the Stars
The Size and Scale of the Universe
• In the 1600s, Nicolaus Copernicus noticed that
the planets appeared to move relative to each
other but that the stars did not. Thus, he thought
that the stars must be much farther away than the
planets.
• Measuring Distance in Space A light-year is a
unit of length equal to the distance that light
travels in 1 year.
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Chapter 18
Section 3 Mapping the Stars
The Size and Scale of the Universe,
continued
• It is important to consider scale when thinking
about the universe. Although stars looks tiny in
the night sky, remember that they are actually a
lot larger than Earth.
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Chapter 18
Section 3 Mapping the Stars
The Doppler Effect
• What Is the Doppler Effect? Have you ever
noticed that when a driver in an approaching car
blows the horn, the horn sounds higher pitched as
the car approaches and lower pitched after the
car passes? This effect is called the Doppler
effect.
• An Expanding Universe The Doppler effect has
been used to discover that galaxies are rapidly
moving apart from each other.
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Chapter 18
Section 3 Mapping the Stars
Red Shift
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Chapter 18
Studying Space
Concept Map
Use the terms below to complete the concept map on
the next slide.
declination
zenith
equator
horizon
celestial objects
altitude
celestial equator
astronomy
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Chapter 18
Studying Space
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Chapter 18
Studying Space
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End of Chapter 18 Show
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Chapter 18
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Reading
Read each of the passages. Then, answer the
questions that follow each passage.
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Chapter 18
Standardized Test Preparation
Passage 1 In the early Roman calendar, a year had
exactly 365 days. The calendar worked well until
people realized that the seasons were beginning and
ending later each year. To fix this problem, Julius
Caesar developed the Julian calendar based on a
365.25-day calendar year. He added 90 days to the
year 46 BCE and added an extra day every 4 years. A
year in which an extra day is added to the calendar is
called a leap year.
Continued on next slide
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Passage 1, continued In the mid-1500s,
astronomers determined that there are actually
365.2422 days in a year, so Pope Gregory XIII
developed the Gregorian calendar. He dropped 10 days
from the year 1582 and restricted leap years
to years that are divisible by 4 but not by 100 (except
for years that are divisible by 400). Today, most
countries use the Gregorian calendar.
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Chapter 18
Standardized Test Preparation
1. According to the passage, which of the following
years is a leap year?
A 46 BCE
B 1582
C 1600
D 1800
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Chapter 18
Standardized Test Preparation
1. According to the passage, which of the following
years is a leap year?
A 46 BCE
B 1582
C 1600
D 1800
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Chapter 18
Standardized Test Preparation
2. How long is a year?
F 365 days
G 365.224 days
H 365.2422 days
I 365.25 days
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Chapter 18
Standardized Test Preparation
2. How long is a year?
F 365 days
G 365.224 days
H 365.2422 days
I 365.25 days
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Chapter 18
Standardized Test Preparation
3. Why did Julius Caesar change the early Roman
calendar?
A to deal with the fact that the seasons were beginning
and ending later each year
B to compete with the Gregorian calendar
C to add an extra day every year
D to shorten the length of a year
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Chapter 18
Standardized Test Preparation
3. Why did Julius Caesar change the early Roman
calendar?
A to deal with the fact that the seasons were beginning
and ending later each year
B to compete with the Gregorian calendar
C to add an extra day every year
D to shorten the length of a year
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Passage 2 The earliest known evidence of
astronomical observations is a group of stones near
Nabta in southern Egypt that is between 6,000 and
7,000 years old. According to archeoastronomers,
some of the stones are positioned such that
they would have lined up with the sun during the
summer solstice 6,000 years ago. The summer
solstice occurs on the longest day of the year. At the
Nabta site, the noonday sun is at its zenith
(directly overhead) for about three weeks before and
after the summer solstice.
Continued on next slide
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Passage 2, continued When the sun is at its zenith,
upright objects do not cast shadows. For many
civilizations in the Tropics, the zenith sun has had
ceremonial significance for thousands of years. The
same is probably true for the civilizations that used the
Nabta site. Artifacts found at the site near Nabta
suggest that the site was created by African cattle
herders. These people probably used the site for
many purposes, including trade, social bonding, and
ritual.
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Chapter 18
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1. In the passage, what does archeoastronomer mean?
A an archeologist that studies Egyptian culture
B an astronomer that studies the zenith sun
C an archeologist that studies ancient astronomy
D an astronomer that studies archeologists
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Chapter 18
Standardized Test Preparation
1. In the passage, what does archeoastronomer mean?
A an archeologist that studies Egyptian culture
B an astronomer that studies the zenith sun
C an archeologist that studies ancient astronomy
D an astronomer that studies archeologists
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Chapter 18
Standardized Test Preparation
2. Why don’t upright objects cast a shadow when the
sun is at its zenith?
F because the sun is directly overhead
G because the summer solstice is occurring
H because the sun is below the horizon
I because the sun is at its zenith on the longest day
of the year
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Chapter 18
Standardized Test Preparation
INTERPRETING GRAPHICS
The diagram on the following slide shows a galaxy
moving in relation to four observers. The concentric
circles illustrate the Doppler effect at each location.
Use the diagram to answer the questions that follow.
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Chapter 18
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1. Which of the following observers would see the light
from the galaxy affected by redshift?
A observers 1 and 2
B observer 3
C observers 3 and 4
D observers 1 and 4
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Chapter 18
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1. Which of the following observers would see the light
from the galaxy affected by redshift?
A observers 1 and 2
B observer 3
C observers 3 and 4
D observers 1 and 4
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Chapter 18
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2. Which of the following observers would see the light
from the galaxy affected by blueshift?
F observer 1
G observers 2 and 4
H observers 3 and 4
I observer 2
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Chapter 18
Standardized Test Preparation
2. Which of the following observers would see the light
from the galaxy affected by blueshift?
F observer 1
G observers 2 and 4
H observers 3 and 4
I observer 2
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Chapter 18
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3. How would the wavelengths of light detected by observer
4 appear?
A The wavelengths would appear shorter than they really
are.
B The wavelengths would appear longer than they really are.
C The wavelengths would appear unchanged.
D The wavelengths would alternate between blue and red.
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Chapter 18
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3. How would the wavelengths of light detected by observer
4 appear?
A The wavelengths would appear shorter than they really
are.
B The wavelengths would appear longer than they really are.
C The wavelengths would appear unchanged.
D The wavelengths would alternate between blue and red.
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Chapter 18
Standardized Test Preparation
MATH
Read each of the following questions, and choose the
best answer.
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Chapter 18
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1. If light travels 300,000 km/s, how long does light
reflected from Mars take to reach Earth when Mars is
65,000,000 km away?
A 22 s
B 217 s
C 2,170 s
D 2,200 s
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Chapter 18
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1. If light travels 300,000 km/s, how long does light
reflected from Mars take to reach Earth when Mars is
65,000,000 km away?
A 22 s
B 217 s
C 2,170 s
D 2,200 s
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Chapter 18
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2. Star A is 8 million kilometers from star B. What is
this distance expressed in meters?
F 0.8 m
G 8,000 m
H 8 X 106 m
I 8 X 109 m
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Chapter 18
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2. Star A is 8 million kilometers from star B. What is
this distance expressed in meters?
F 0.8 m
G 8,000 m
H 8 X 106 m
I 8 X 109 m
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Chapter 18
Standardized Test Preparation
3. If each hexagonal mirror in the Keck Telescopes is
1.8 m across, how many mirrors would be needed to
create a light-reflecting surface that is 10.8 m across?
A 3.2
B5
C6
D 6.2
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Chapter 18
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5. You are studying an image made by the Hubble
Space Telescope. If you observe 90 stars in an area
that is 1 cm2 , which of the following estimates is the
best estimate for the number of stars in 15 cm2 ?
A 700
B 900
C 1,200
D 1,350
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Chapter 18
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5. You are studying an image made by the Hubble
Space Telescope. If you observe 90 stars in an area
that is 1 cm2 , which of the following estimates is the
best estimate for the number of stars in 15 cm2 ?
A 700
B 900
C 1,200
D 1,350
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Chapter 18
Section 1 Astronomy: The Original
Science
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Chapter 18
Section 1 Astronomy: The Original
Science
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Chapter 18
Standardized Test Preparation
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Chapter 18
CNN Videos
• Discovering a New Planet
• Taking Earth's Pulse
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