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The Solar System
Table of Contents
Observing the Solar System
The Sun
The Inner Planets
The Outer Planets
Comets, Asteroids, and Meteors
Is There Life Beyond Earth?
The Solar System - Observing the Solar System
Geocentric System
In a geocentric system, Earth is at the center of the revolving
planets and stars.
The Solar System - Observing the Solar System
Heliocentric System
In a heliocentric system, Earth and the other planets revolve
around the sun.
The Solar System - Observing the Solar System
The Sun and Planets
Shown below are the average distances of
each planet from the sun.
The Solar System - Observing the Solar System
Solar System Activity
Click the Active Art button to open a browser window and
access Active Art about the solar system.
The Solar System - Observing the Solar System
Planet Speed Versus Distance
Johannes Kepler discovered a
relationship between the speed
of a planet and its distance from
the sun. Use the graph to
discover what Kepler learned.
The Solar System - Observing the Solar System
Planet Speed Versus Distance
Reading Graphs:
According to the graph, what
is Earth’s average speed?
About 30 km/s
The Solar System - Observing the Solar System
Planet Speed Versus Distance
Interpreting Data:
Which is closer to the sun,
Mercury or Mars? Which
moves faster?
Mercury; Mercury
The Solar System - Observing the Solar System
Planet Speed Versus Distance
Drawing Conclusions:
What is the general
relationship between a
planet’s speed and its
average distance from the
sun?
Planets that are closer to the
sun move faster.
The Solar System - Observing the Solar System
Planet Speed Versus Distance
Predicting:
The planet Uranus is about
2,900 million km from the sun.
Predict whether its speed is
greater or less than Jupiter's
speed. Explain your answer.
Uranus’s speed is less than
that of Jupiter because
Uranus is farther from the sun
than Jupiter.
The Solar System - Observing the Solar System
Previewing Visuals
Preview Figure 2 and Figure 3. Then write two questions you
have about Earth’s history in a graphic organizer like the one
below. As you read, answer your questions.
Models of the Universe
Q. What is a geocentric model?
A. A model that shows Earth at the center of the revolving planets
and stars
Q. What is a heliocentric system?
A. A model that shows Earth and the other planets revolving
around the sun
The Solar System
End of Section:
Observing the
Solar System
The Solar System - The Sun
The Layers of the Sun
The sun has an interior and an
atmosphere, each of which
consists of several layers.
The Solar System - The Sun
Outlining
As you read, make an outline
about the sun that you can
use for review. Use the red
headings for the main topics
and the blue headings for the
subtopics.
The Sun
I. The Sun’s Interior
A. The Core
B. The Radiation Zone
C. The Convection Zone
II. The Sun’s Atmosphere
A. The Photosphere
B. The Chromosphere
C. The Corona
III. Features on the Sun
A. Sunspots
B. Prominences
C. Solar Flares
D. Solar Wind
The Solar System - The Sun
More on the Sun
Click the Planet Diary button for an activity about the sun.
The Solar System
End of Section:
The Sun
The Solar System - The Inner Planets
The Inner Planets
The inner planets take up only a small part of the solar
system. Note that sizes and distances are not drawn to scale.
The Solar System - The Inner Planets
Earth’s Layers
Earth has three main layers—a crust, a mantle, and a core.
The Solar System - The Inner Planets
Mercury
Mercury is the smallest terrestrial planet and the planet
closest to the sun.
The Solar System - The Inner Planets
Venus
Venus’s density and internal structure are similar to Earth’s.
But, in other ways, Venus and Earth are very different.
The Solar System - The Inner Planets
Venus
This figure combines images of Venus taken from space with a
camera (left) and radar (right). The camera image shows
Venus’s thick atmosphere. Radar is able to penetrate Venus’s
clouds to reveal the surface. Both images are false color.
The Solar System - The Inner Planets
Mars
Mars is called the “red planet.” When you see it in the sky, it
has a slightly reddish tinge. This reddish color is due to the
breakdown of iron-rich rocks, which creates a rusty dust that
covers much of Mars’s surface.
The Solar System - The Inner Planets
Mars
Mares has ice caps at both poles. Scientists think that a large
amount of liquid water flowed on Mars's surface in the distant
past.
The Solar System - The Inner Planets
Using Prior Knowledge
Look at the section headings and visuals to see what this
section is about. Then write what you know about the inner
planets in a graphic organizer like the one below. As you
read, write what you learn.
What You Know
1.
2.
3.
4.
Most of Earth is covered with water.
Mercury is closest to the sun.
Venus is very hot.
Mars is called the “red planet.”
What You Learned
1.
2.
3.
4.
Earth is unique in our solar system for having liquid water at its surface.
Mercury has a greater temperature range than any of the other planets.
A day on Venus is longer than its year.
The reddish tinge on Mars is caused by the breakdown of iron-rich
rocks.
The Solar System - The Inner Planets
Links on the Planets
Click the SciLinks button for links on the planets.
The Solar System
End of Section:
The Inner Planets
The Solar System - The Outer Planets
Gas Giants and Pluto
The first four outer planets–Jupiter, Saturn, Uranus, and
Neptune–are much larger and more massive than Earth, and
they do not have solid surfaces. Pluto is small and rocky.
The Solar System - The Outer Planets
Jupiter’s Structure
Jupiter is composed mainly of the elements hydrogen and
helium.
The Solar System - The Outer Planets
Jupiter’s Moons
The astronomer Galileo
discovered Jupiter’s four largest
moons. They are named Io,
Europa, Ganymede, and
Callisto.
The Solar System - The Outer Planets
Saturn
Saturn has the most spectacular rings of any planet.
The Solar System - The Outer Planets
Uranus
Although the gas giant Uranus is about four times the
diameter of Earth, it is still much smaller than Jupiter and
Saturn.
The Solar System - The Outer Planets
Uranus
Uranus’s axis of rotation is tilted at an angle of about 90
degrees from the vertical.
The Solar System - The Outer Planets
Neptune
Neptune is a cold, blue planet. Its atmosphere contains
visible clouds.
The Solar System - The Outer Planets
Circumference
To calculate the circumference of a circle, use this formula:
C = 2πr
In the formula, π ≈ 3.14, and r is the circle’s radius, which is
the distance from the center of the circle to its edge. The
same formula can be used to calculate the circumference of
planets, which are nearly spherical.
Neptune’s radius at its equator is about 24,800 km.
Calculate its circumference.
C = 2πr
= 2.00 X 3.14 X 24,800 km
= 156,000 km
The Solar System - The Outer Planets
Circumference
Practice Problem
Saturn’s radius is 60,250 km. What is its circumference?
2 X 3.14 X 60,250 km = about 378,800 km
The Solar System - The Outer Planets
Pluto
Pluto has a solid surface and is much smaller and denser
than the other outer planets.
The Solar System - The Outer Planets
Identifying Main Ideas
As you read the section “Gas Giants and Pluto,” write the
main idea–the biggest or most important idea–in a graphic
organizer like the one below. Then write supporting details
that further explain the main idea.
Main Idea
The four gas giants are similar in…
Detail
Structure–
they do not
have a solid
surface.
Detail
Detail
Detail
Atmosphere–
thick and made
up mainly of
hydrogen and
helium.
Rings–
each is
surrounded by
a set of rings.
Size and mass–
each is very
large and
massive.
The Solar System - The Outer Planets
More on the Planets
Click the PHSchool.com button for an activity
about the planets.
The Solar System
End of Section:
The Outer
Planets
The Solar System - Comets, Asteroids, and Meteors
Structure of a Comet
The main parts of a comet are the nucleus, the coma, and
the tail. Most comets have two tails—a bluish gas tail and a
white dust tail.
The Solar System - Comets, Asteroids, and Meteors
Comet Orbits
Most comets revolve around the sun in very long, narrow
orbits. Gas and dust tails form as the comet approaches
the sun.
The Solar System - Comets, Asteroids, and Meteors
The Asteroid Belt
Most asteroids revolve
around the sun between
the orbits of Mars and
Jupiter. This region is
called the asteroid belt.
The Solar System - Comets, Asteroids, and Meteors
Comparing and Contrasting
As you read, compare and contrast comets, asteroids, and
meteoroids by completing a table like the one below.
Comets, Asteroids, and Meteoroids
Feature
Comets
Asteroids
Meteoroids
Origin
Kuiper belt and Oort
cloud
Between the orbits of
Mars and Jupiter
Comets or asteroids
Size
Excluding the tail,
about the size of a
mountain
Typically less than 1
km; some are more
than 300 km in
diameter
Smaller than comets
or asteroids
Composition
Ice, dust, small rocky
particles
Rock
Rock or dust
The Solar System - Comets, Asteroids, and Meteors
Links on Comets, Asteroids, and Meteors
Click the SciLinks button for links on comets,
asteroids, and meteors.
The Solar System
End of Section:
Comets,
Asteroids, and
Meteors
The Solar System - Is There Life Beyond Earth?
Asking Questions
Before you read, preview the red headings. In a graphic
organizer like the one below, ask a question for each
heading. As you read, write answers to your questions.
Question
Answer
What are the
“Goldilocks”conditions?
The favorable conditions on
Earth that allow life to exist
Is there life on Mars?
Scientists have not yet found
evidence for life on Mars.
Why do scientists think Europa
might have life?
Europa has an ice crust that
could have a liquid water ocean
underneath.
The Solar System - Is There Life Beyond Earth?
Links on Extraterrestrial Life
Click the SciLinks button for links on extraterrestrial life.
The Solar System
End of Section:
Is There Life
Beyond Earth?
The Solar System
Graphic Organizer
Feature
Geocentric
System
Heliocentric
System
Object at center
Earth
Sun
Objects that move
around center
Planets and sun
Planets
Proposed by
Early Greek
astronomers
Copernicus
Supporters
Ptolemy
Brahe, Kepler,
Galileo
The Solar System
End of Section:
Graphic Organizer