Observing the Solar System

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Table of Contents

• Observing the Solar System
• The Sun
• The Inner Planets
• The Outer Planets
• Comets, Asteroids, and Meteors
• Is There Life Beyond Earth?

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3-1 Observing the Solar System
Observer Approx. Date Accomplishment
Greek Scientists    
Ptolemy    
Copernicus    
Galileo    
Brahe    
Kepler    
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Geocentric
Heliocentric
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Geocentric System
- Observing the Solar System

• In a geocentric system, Earth is at the center of
  the revolving planets and stars.

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Heliocentric System
- Observing the Solar System

• In a heliocentric system, Earth and the other
  planets revolve around the sun.

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The Sun and Planets
- Observing the Solar System

• Shown below are the average distances of each
  planet from the sun.

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Solar System Activity
- Observing the Solar System

• Click the Active Art button to open a browser
  window and access Active Art about the solar
  system.

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Planet Speed Versus Distance
- Observing the Solar System

• 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.

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Planet Speed Versus Distance
- Observing the Solar System

• Reading Graphs
• According to the graph, what is Earths average
  speed?

• About 30 km/s

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Planet Speed Versus Distance
- Observing the Solar System

• Interpreting Data
• Which is closer to the sun, Mercury or Mars?
  Which moves faster?

• Mercury Mercury

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Planet Speed Versus Distance
- Observing the Solar System

• Drawing Conclusions
• What is the general relationship between a
  planets speed and its average distance from the
  sun?

• Planets that are closer to the sun move faster.

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Planet Speed Versus Distance
- Observing the Solar System

• 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.

• Uranuss speed is less than that of Jupiter
  because Uranus is farther from the sun than
  Jupiter.

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Previewing Visuals
- Observing the Solar System

• Preview Figure 2 and Figure 3. Then write two
  questions you have about Earths 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
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End of SectionObserving the Solar System
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The Layers of the Sun
- The Sun

• The sun has an interior and an atmosphere, each
  of which consists of several layers.

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Outlining
- The Sun
The Sun

• The Suns Interior
• The Core
• The Radiation Zone
• The Convection Zone
• The Suns Atmosphere
• The Photosphere
• The Chromosphere
• The Corona
• Features on the Sun
• Sunspots
• Prominences
• Solar Flares
• Solar Wind

• 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.

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More on the Sun
- The Sun

• Click the Planet Diary button for an activity
  about the sun.

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End of SectionThe Sun
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Size of the Solar System

• Our Solar System is 2 light years wide.

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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.

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Mercury
- The Inner Planets

• Mercury is the smallest terrestrial planet and
  the planet closest to the sun.

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Mercury
- The Inner Planets

• Mercury surface is covered by a thin layer of
  minerals called silicates
• Mercury is dry, extremely hot, and almost
  airless.
• Mercury does not have enough gases in its
  atmosphere to reduce the amount of heat and light
  it receives from the sun.

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Venus
- The Inner Planets

• Venuss density and internal structure are
  similar to Earths. But, in other ways, Venus and
  Earth are very different.

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Venus
- The Inner Planets

• This figure combines images of Venus taken from
  space with a camera (left) and radar (right). The
  camera image shows Venuss thick atmosphere.
  Radar is able to penetrate Venuss clouds to
  reveal the surface. Both images are false color.

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Venus

• The surface of Venus is extremely hot and dry.
  There is no liquid water on the planet's surface
  because the high temperature would cause any
  liquid to boil away.
• Venus has a variety of surface features, plains,
  mountains, canyons, and valleys.
• The atmosphere consists primarily of carbon
  dioxide.

Thick clouds of sulfuric acid cover Venus.
Maat Mons, a mountain on Venus.
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Earths Layers
- The Inner Planets

• Earth has three main layersa crust, a mantle,
  and a core.

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Mars
- The Inner Planets

• 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 Marss surface.

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Mars
- The Inner Planets
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Mars
- The Inner Planets

• Mars has ice caps at both poles. Scientists think
  that a large amount of liquid water flowed on
  Mars's surface in the distant past.

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Mars Atmosphere
- The Inner Planets
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Using Prior Knowledge
- The Inner Planets

• 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. Most of Earth is covered with water.
2. Mercury is closest to the sun.
3. Venus is very hot.
4. Mars is called the red planet.

What You Learned

1. Earth is unique in our solar system for having
   liquid water at its surface.
2. Mercury has a greater temperature range than any
   of the other planets.
3. A day on Venus is longer than its year.
4. The reddish tinge on Mars is caused by the
   breakdown of iron-rich rocks.

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Links on the Planets
- The Inner Planets

• Click the SciLinks button for links on the
  planets.

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End of SectionThe Inner Planets
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Gas Giants and Pluto
- The Outer Planets

• The four outer planetsJupiter, Saturn, Uranus,
  and Neptuneare much larger and more massive than
  Earth, and they do not have solid surfaces. Pluto
  is small and rocky.

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Jupiter Compared to Earth
- The Outer Planets
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Jupiters Structure
- The Outer Planets

• Jupiter is composed mainly of the elements
  hydrogen and helium.

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Jupiters Structure
- The Outer Planets

• Jupiter is a giant ball of gas and liquid with
  little, if any, solid surface.
• Atmosphere86 Hydrogen and 14 Helium
• Chemicals have formed colorful layers of clouds
  at different heights. The highest white clouds in
  the zones are made of crystals of frozen ammonia.
  Darker, lower clouds of other chemicals occur in
  the belts

The planet Jupiter's Great Red Spot is a huge mass of swirling gas. At its widest, it is about three times the diameter of the Earth. Image credit NASA

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Jupiters Moons
- The Outer Planets

• 63 Moons Total!
• Only 16 are wider than 6 miles across!
• Galileo discovered Jupiters four largest moons.
  They are named Io, Europa, Ganymede, and Callisto.

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Jupiters Random, But Totally Cool Fact
- The Outer Planets
49Number of named moons - also known as natural satellites - orbiting Jupiter.
6Years it took the Galileo spacecraft to reach Jupiter.
1,321Number of Earths that could fit inside Jupiter.
59Minutes NASA's Galileo probe survived before it was crushed by the intense pressure of Jupiter's atmosphere.
3The number of rings around Jupiter.
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Saturn
- The Outer Planets
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Saturn
- The Outer Planets

• Saturn is made mostly of hydrogen and helium. The
  surface and merges into its atmosphere.
• The seven rings make up Saturn. They are made up
  of billions of pieces of ice. These pieces range
  from ice particles that are the size of dust to
  chunks of ice that measure more than 10 feet in
  diameter.

The dark side of Saturn's rings was photographed by Voyager 1 as it flew by the side opposite the sun. The dense B-ring -- the reddish-brown band -- appears dark because it blocks much of the sunlight. It is the brightest ring when viewed from earth. Image credit JPL
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Saturns Random, But Totally Cool Fact
- The Outer Planets
70,700 mphSpeed of the Cassini spacecraft as it traveled to Saturn.
5,600Number of years it would take to travel the same distance as Cassini at 60 mph.
1Percentage of time Cassini's engines will burn during the mission. The other 99 is all cruising.
52Number of named moons orbiting Saturn.
1,100 mphWind speeds at Saturn's equator. About 1,800 kph. Earth's most violent tornadoes hit 200 mph.
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Uranus
- The Outer Planets

• Although the gas giant Uranus is about four times
  the diameter of Earth, it is still much smaller
  than Jupiter and Saturn.

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Uranus
- The Outer Planets

• The surface of Uranus consists of blue-green
  clouds made up of tiny crystals of methane.
• Far below the visible clouds are probably thicker
  cloud layers made up of liquid water and crystals
  of ammonia ice.

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Uranus
- The Outer Planets

• Uranuss axis of rotation is tilted at an angle
  of about 90 degrees from the vertical.

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- The Outer Planets
Neptune is the only planet that cannot be seen
without a telescope
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Neptune

• Neptunes bluish color is caused by small amounts
  of methane gas in its atmosphere.
• The planet has 13 moons and a very narrow, faint
  ring system.

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Neptune

• Neptunes bluish color is caused by small amounts
  of methane gas in its atmosphere. The atmosphere
  is mostly hydrogen, helium and water.
• The planet has 13 moons and a very narrow, faint
  ring system.

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Neptune

• Neptune may be the windiest planet in the solar
  system. Winds tear through the clouds at more
  than 1,200 mph 
• Scientists think there might be an ocean of super
  hot water under Neptune's cold clouds. It does
  not boil away because of the incredible
  pressure. 

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Pluto
- The Outer Planets

• Pluto has a solid surface and is much smaller and
  denser than the other outer planets.

3!
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Pluto
- The Outer Planets
From Pluto, our Sun would look like a very bright
star.
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Pluto

• The surface of Pluto is made of two parts? An icy
  part made of nitrogen and a non-icy part.
• The air is made mostly of nitrogen.
• Pluto may in the group of icy objects just beyond
  Neptune called the Kuiper Belt. The Kuiper Belt
  is made up of millions of icy and rocky objects.

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Identifying Main Ideas
- The Outer Planets

• As you read the section Gas Giants and Pluto,
  write the main ideathe biggest or most important
  ideain 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
Detail
Detail
Detail
Structure they do not have a solid surface.
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.
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More on the Planets
- The Outer Planets

• Click the PHSchool.com button for an
  activityabout the planets.

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End of SectionThe Outer Planets
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Structure of a Comet
- Comets, Asteroids, and Meteors

• The main parts of a comet are the nucleus, the
  coma, and the tail. Most comets have two tailsa
  bluish gas tail and a white dust tail.

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Comet Orbits
- Comets, Asteroids, and Meteors

• Most comets revolve around the sun in very long,
  narrow orbits. Gas and dust tails form as the
  comet approachesthe sun.

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The Asteroid Belt
- Comets, Asteroids, and Meteors

• Most asteroids revolve around the sun between the
  orbits of Mars and Jupiter. This region is called
  the asteroid belt.

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Comparing and Contrasting
- Comets, Asteroids, and Meteors

• 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
Kuiper belt and Oort cloud
Between the orbits of Mars and Jupiter
Origin
Comets or asteroids
Typically less than 1 km some are more than 300
km in diameter
Excluding the tail, about the size of a mountain
Smaller than comets or asteroids
Size
Ice, dust, small rocky particles
Composition
Rock
Rock or dust
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Links on Comets, Asteroids, and Meteors
- Comets, Asteroids, and Meteors

• Click the SciLinks button for links on
  comets,asteroids, and meteors.

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End of SectionComets, Asteroids, and Meteors
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Asking Questions
- Is There Life Beyond Earth?

• 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.

What are the Goldilocksconditions?
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.
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Links on Extraterrestrial Life
- Is There Life Beyond Earth?

• Click the SciLinks button for links on
  extraterrestrial life.

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End of SectionIs There Life Beyond Earth?
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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
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End of SectionGraphic Organizer