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Chapter 14 The Solar System
Greek Word Origins
Greek Word
astron
chroma
geo
helios
kentron
photo
sphaira
Meaning
Key Terms
star
color
Earth
sun
near the center; central
light
sphere
astronomy, asteroid
chromosphere
geocentric, geology
heliocentric
geocentric, heliocentric
photosphere
photosphere, chromosphere
Chapter 14 The Solar System
Section 1:
Observing the
Solar System
What are the geocentric and heliocentric systems?
How did Copernicus, Galileo, and Kepler contribute to our
knowledge of the solar system?
What objects make up the solar system?
Chapter 14 The Solar System
Greek Observations of the Sky
The Greeks noticed how patterns of stars,
called constellations, kept the same
shapes from night to night and year to
year. Meanwhile, the planets seemed to
wander among them. . .
Constellation figures
Some common constellations
Chapter 14 The Solar System
Geocentric System
Early Greek astronomers believed
in a geocentric system which has
the Earth at the center of the
revolving planets and stars.
About A.D. 140, the Greek
astronomer Ptolemy further
developed the geocentric model.
His model of the universe was
widely accepted for the next 1,500
years until . . .
Chapter 14 The Solar System
Ptolemy’s Complicated Model
Chapter 14 The Solar System
The Copernican Revolution!
Most people, including
scientists, at this time
couldn’t accept that Earth
was not the center of the
universe.
However, in 1543, the
Polish astronomer
Nicolaus Copernicus
worked out the
arrangement of the known
planets and how they
move around the sun. His
findings revolutionized the
science of astronomy.
Chapter 14 The Solar System
The Copernican Revolution
Chapter 14 The Solar System
Heliocentric System
In a heliocentric system, Earth
and the other planets revolve
around the sun.
In the 1600’s, Galileo Galilei
used the newly invented
telescope to make discoveries
that supported the heliocentric
model.
Chapter 14 The Solar System
Galileo’s Evidence
Galileo found moons
revolving around Jupiter
and saw that Venus has
phases like the moon.
These findings further
proved the heliocentric
theory.
However, due to his
controversial teachings
and books, he was found
guilty of heresy, and was
placed under house arrest
by the Pope.
Chapter 14 The Solar System
Galileo’s Discoveries
Chapter 14 The Solar System
Motions of the Planets
For more than 20 years in the late 1500’s,
Danish astronomer Tyco Brahe observed
and recorded the positions of the planets.
After Brahe’s death in 1601, his assistant, Johannes Kepler, used
this data to develop three laws that describe the motions of the
planets.
Chapter 14 The Solar System
Tyco Bites the Dust
Chapter 14 The Solar System
Kepler’s Three Laws of Planet Motion
First Law: The orbit of each planet in the solar system is an ellipse,
an elongated circle (not a perfect circle as previously thought).
Second Law: Each planet moves faster
when it is closer to the sun and slower when
it is farther away.
Third Law: Planets closer to the sun orbit
faster than planets that are farther from the Sun.
OR
“The square of the orbital period of a planet is directly proportional to the
cube of the semi-major axis of its orbit.”
Chapter 14 The Solar System
Modern View of the Solar System
The planets vary greatly in size and
appearance. They also differ in
terms of mass, composition, axis tilt,
and distance from the Sun.
To measure the great distances in
the solar system, scientists use
astronomical units (AU). One AU
equals Earth’s average distance
from the sun (about 150 million km).
Chapter 14 The Solar System
The Sun and Planets
Shown below are the average distances of the
planets and Pluto (a dwarf planet) from the sun.
The solar system also includes smaller objects,
such as comets and asteroids.
Chapter 14 The Solar System
Section 2:
The Sun
How does the sun produce energy?
What are the layers of the sun’s interior and the
sun’s atmosphere?
What features form on or above the sun’s surface?
Chapter 14 The Solar System
The Sun
The sun is a huge ball of ionized gas
(or plasma) that accounts for 99.8%
of the solar system’s total mass.
It is about ¾ hyrdogen and ¼ helium,
plus small amounts of other elements.
Due to its mass, its gravity is strong
enough the hold all the planets and
other distant objects in orbit.
Is the sun a planet? A moon?
If not, then what is it? It is a star!
Chapter 14 The Solar System
Nuclear Fusion
The sun’s energy is produced through nuclear fusion. This is when
two atomic nuclei collide and combine, forming a larger nucleus and
releasing energy in the process. What elements do we start and end
with?
Hydrogen
& Helium
Chapter 14 The Solar System
The Layers of the Sun
The sun has an
interior and an
atmosphere,
each of which
consists of three
layers.
Chapter 14 The Solar System
The Sun’s Interior
The sun’s interior consist of the core, the
radiation zone, and the convection
zone.
Core: The sun’s energy is produced here
by fusion since temperature and
pressure are so high.
Radiation Zone: Middle layer of sun’s
interior where energy is transferred by
radiation through tightly packed gases.
Convection Zone: Outermost layer of
sun’s interior where hot gases rise to
surface and cooler gases sink by
convection.
Chapter 14 The Solar System
The Sun’s Atmosphere
The sun’s atmosphere includes the photosphere, the
chromosphere and the corona.
Photosphere: The inner layer of the
sun’s atmosphere. It is the visible
surface of the sun (i.e. what you see).
Chromosphere: Thin, reddish layer of
sun’s atmosphere just outside of the
photosphere.
Corona: Outermost layer of the sun’s
atmosphere which appears as a white
halo around the sun. It means “crown”
in Latin.
When can we see the corona? During a solar eclipse
Chapter 14 The Solar System
Features on the Sun
Sunspots: Areas of gas on the sun’s surface that are
cooler than the surrounding gases. They seem to move
across the surface, showing that the sun rotates just like
the Earth. The number of sunspots varies in 11 year cycles.
Prominences: Huge loops of reddish gas which
often link sunspot regions. In the picture on the left,
the Earth is about the size of this dot  .
Solar Flares: Eruptions which send hot gases
and millions of joules of energy streaming out
into space at about ½ the speed of light.
Chapter 14 The Solar System
Solar Wind
The corona extends out into space millions of kilometers until it thins
into streams of electrically charged particles known as solar wind.
Solar flares can cause great increases
in the number of these particles that reach
Earth. They can damage satellites,
disrupting radio, TV and telephone signals.
However, at the poles, these particles can
enter our atmosphere, exciting gas particles
to create auroras.
Earth’s magnetosphere protects
us from these particles.
Chapter 14 The Solar System
Aurora Explanation
Chapter 14 The Solar System
Section 3:
The Inner Planets
What characteristics do the inner planets have in
common?
What are the main characteristics that distinguish each of
the inner planets?
Chapter 14 The Solar System
The Inner Planets
The four inner planets—Mercury, Venus, Earth and Mars—are
similar in that they are small and dense and have rocky surfaces.
They are often called the terrestrial planets, from the Latin word
terra, which means “Earth.”
Chapter 14 The Solar System
The Inner Planets
The inner planets take up only a small part of the solar system.
Notice the differences in rotation and revolution times.
Sizes and distances are not drawn to scale.
Chapter 14 The Solar System
Earth’s Layers
Earth is unique in our solar system in having liquid water at its
surface (about 70% of the Earth’s surface).
Earth has three main layers—a crust, a mantle, and a core.
Earth has enough gravity to hold on to
most gases, like nitrogen and oxygen.
These gas make up our atmosphere
which extends more than 100 km
above its surface.
Chapter 14 The Solar System
Mercury
Mercury is the smallest terrestrial planet and the planet
closest to the sun. It is covered with impact craters.
Since it so small, it doesn’t have enough gravity to hold an
atmosphere. Therefore, its temperature varies greatly, from
430 degrees C to -170 degrees C.
Chapter 14 The Solar System
Venus
Venus’s density and internal structure are similar to Earth’s, but
they are still quite different.
The atmosphere is mostly carbon dioxide with clouds of sulfuric
acid.
Atmospheric pressure is 90 times greater than Earth’s.
Its average surface temperature is 460° C, hot enough to melt
lead.
Chapter 14 The Solar System
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 use false color.
Chapter 14 The Solar System
Mars—The Red Planet
Mars is red because of the iron-rich dust that covers its surface.
The thin atmosphere of Mars is more than 95% carbon dioxide.
It’s surface temperatures range from -140°C to 20°C.
It’s surface is rugged and rocky,
with evidence of ancient volcanoes
and lava flows.
Mars
Mars has two tiny moons, Phobos (27km) and Deimos (15km).
It’s tilted axis means it must have what phenomenon? Seasons
Chapter 14 The Solar System
Mars—Is there water?
Mars has ice caps at both poles.
The ice is made up of water and
carbon dioxide (dry ice).
Surface features that look like
ancient streambeds and river
canyons make scientists think
that a large amount of liquid
water once flowed on Mars's
surface.
There may even be a large
amount of water frozen
underground.
Chapter 14 The Solar System
Section 4:
The Outer Planets
What characteristics do the gas giants have in common?
What characteristics distinguish each of the outer planets?
Chapter 14 The Solar System
Gas Giants and Pluto
The 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.
Chapter 14 The Solar System
Jupiter’s Structure
Jupiter is composed mainly of the elements hydrogen and helium.
Chapter 14 The Solar System
Jupiter
Has a core of rock and iron
surrounded by liquid
hyrdogen and helium. It has
four large moons but dozens
of smaller ones.
The Giant Red Spot on Jupiter is
huge storm that is larger than
Earth!
It is the largest and most
massive planet in our solar
system.
Chapter 14 The Solar System
Saturn
Saturn has the most spectacular rings of any planet. It has a
very thick atmosphere made of hydrogen and helium with
visible clouds and even storms.
Rings: made of
small particles of
ice and dust.
Chapter 14 The Solar System
Uranus
Although the gas giant Uranus is about four times the
diameter of Earth, it is still much smaller than Jupiter and
Saturn. It is very cold with clouds likely made of methane.
It has at least 27 moons.
Chapter 14 The Solar System
Uranus
Uranus’s axis of rotation is tilted at an angle of about 90
degrees from the vertical.
Chapter 14 The Solar System
Neptune
Neptune is a cold, blue planet. Its atmosphere contains
visible clouds. It is very cold and often stormy.
It was discovered because it was predicted by a
mathematical calculation. It was affecting the orbital pattern
of Uranus.
Chapter 14 The Solar System
Pluto
Pluto has a solid surface and is much smaller and denser
than any of the outer planets. It is now considered to be a
dwarf planet (or exoplanet).
Chapter 14 The Solar System
Section 5:
Comets, Asteroids,
and Meteors
What are the characteristics of comets?
Where are most asteroids found?
What are meteoroids and how do they form?
Chapter 14 The Solar System
Comets
A comet is a loose collection of ice, dust and small rocky
particles orbiting around the sun.
The most famous comet is probably Halley’s Comet, named
after astronomer, Edmond Halley.
Chapter 14 The Solar System
Structure of a Comet
The main parts of a comet are the nucleus, the coma, and
the tail. The nucleus is deep within the coma. Most comets
have two tails—a bluish gas tail and a white dust tail.
Chapter 14 The Solar System
Comet Orbits
Most comets revolve around the sun in very long, narrow
elliptical orbits.
Gas and dust tails form as the comet approaches the sun.
The gas tail always points away from the sun due to the solar
wind.
Chapter 14 The Solar System
Origin of Comets
Most comets originate from
one of two places:
--The Kuiper Belt: a doughnutshaped region of small icy
bodies on the outer edges of
Neptune’s orbit
--The Oort Cloud: a large,
spherical region of comets
that surrounds the solar
system
Chapter 14 The Solar System
The Asteroid Belt
Most asteroids revolve
around the sun in fairly
circular orbits between the
orbits of Mars and Jupiter.
This region of the solar
system is called the asteroid
belt.
Chapter 14 The Solar System
Meteors
A meteoroid is a chunk of rock or dust in space. They are
created when comets or asteroids collide or break up.
When meteoroid enter Earth’s atmosphere, friction with the
atmosphere creates a streak of light in the sky—a meteor
(also known as a shooting star).
If is it large enough, the meteoroid may not disintegrate and
will strike Earth’s surface as a meteorite. Meteorites
created the craters on the moon and likely wiped out the
dinosaurs 65 mya.
Chapter 14 The Solar System
Section 6:
Is There Life
Beyond Earth?
What conditions do living things need to exist on Earth?
Why do scientists think Mars and Europa are good places
to look for signs of life?
Chapter 14 The Solar System
Life On Earth
Earth has liquid water and a suitable temperature range and
atmosphere for living things to survive. This is called the
“Goldilocks” conditions (“just right”).
Thought most organisms need these things to live, some
extremophiles (organisms in extreme conditions) have
been found to survive in a wide range of conditions
(boiling water, frozen in ice, deep in the ocean, etc.)
Chapter 14 The Solar System
Life on Mars?
Since life as we know it
requires water,
scientists hypothesize
that Mars may have
once had the conditions
needed for life to exist.
Chapter 14 The Solar System
Life on Europa?
Many scientists think the one of Jupiter’s moons, Europa,
may have conditions necessary for life. They hypothesize
that there might be liquid water under its smooth, icy crust.
Chapter 14 The Solar System
Searching for Life in Space