Download Our Solar System in the Universe

Our Solar System in the Universe
Chapters 25 & 26
CH 25: Our
Solar System
WHAT YOU ARE GOING TO LEARN ABOUT:
• Exploring the Solar System – history
• The Earth-Moon System
• The Inner Solar System
• The Outer Solar System
• The Origin of the Solar System
How do science concepts apply to
your world?
Here are some questions you’ll be able to answer after you read this
chapter.
■ How does a spacesuit work?
■ Why shouldn’t you park a car too close to the ocean’s edge?
■ Why isn’t Earth covered by craters?
■ Did Mars once have liquid water?
■ Where, besides Earth, is life most likely to occur in our solar
system?
■ What lies at the outer edges of the solar system?
■ Why do comets have tails?
■ Are there planets around other stars?
FIND the ANSWERS - ACTIVITY
How do science concepts apply to your world?
1. ■ How does a spacesuit work? (Section 25.1)
2. ■ Why shouldn’t you park a car too close to the ocean’s
edge? (Section 25.2)
3. ■ Why isn’t Earth covered by craters? (Section 25.3)
4. ■ Did Mars once have liquid water? (Section 25.3)
5. ■ Where, besides Earth, is life most likely to occur in our
solar system? (Section 25.4)
6. ■ What lies at the outer edges of the solar system? (Section
25.4)
7. ■ Why do comets have tails? (page 816)
8. ■ Are there planets around other stars? (Section 25.5)
CH 25: Pre-Quiz
1. What determines the strength of
the gravitational attraction
between two objects?
a. Mass and weight
b. Weight and distance
c. Mass and distance
d. Distance and density
4. What is Newton’s first law of
motion?
5. Describe Earth’s structure. What
are the three main layers?
2. What are the two most
abundant gases in Earth’s
atmosphere?
3. True or False: Earth’s
atmosphere plays a role in
regulating its surface temperature.
6. Explain the process of
condensation.
Ch 25: Pre-Quiz - KEY
1. What determines the strength of
the gravitational attraction between
two objects? (c)
a. Mass and weight
b.Weight and distance
c. Mass and distance
d. Distance and density
2. What are the two most abundant gases in
Earth’s atmosphere?
(Nitrogen and oxygen)
3. True or False: Earth’s atmosphere plays a
role in regulating its surface temperature.
(True. Earth’s atmosphere plays a major role
in keeping surface temperatures in their
present ranges.)
4. What is Newton’s first law of motion?
(The state of motion of an object does not
change as long as there is no net force acting on
it.)
5. Describe Earth’s structure. What are the
three main layers?
(The three main layers are the crust, or rocky outer
layer; the mantle, a thick layer of hot, solid rock;
and the core, a large sphere found in Earth’s center,
mostly made of iron and nickel.)
6. Explain the process of condensation.
(In condensation, a gas changes into a liquid as it
cools.)
Why do we care to study this?
The Hubble Space Telescope Has Orbited Earth For 25 Years
1 light year = 5.87849981 x 1012 miles
What have you observed?
…the first step in scientific methods
What have you observed?
Ancient Civilizations did too…
– most objects in the sky seem to be in a state of slow
but steady motion.
• The sun and moon appear to rise in the east and set in the west.
• The stars move across the sky in a fixed pattern.
– a few bright star-like objects seemed to wander
slowly among the fixed patterns of stars.
• called planets, from the Greek word for “wanderers.”
– Saw five planets that can be seen with the unaided
eye:
• Mercury, Venus, Mars, Jupiter, and Saturn.
Models of the Solar System
Geocentric Model
Most ancient Greeks thought that all the stars and
planets lay on the inside of a giant sphere that revolved
around Earth once a day.
Ptolemy’s geocentric model was widely accepted for nearly 1400 years
Such a model is called a geocentric model. Which is it?
Models of the Solar System
Heliocentric Model
The Greek astronomer Aristarchus developed a
heliocentric model, with the sun at the center.
• His model was not accepted by most ancient Greeks.
• The geocentric model could explain all observations made
at that time.
1500s - Copernicus realized that the motion of the planets could
be more simply explained if they are revolving around the sun
rather than around Earth.
The observations of Italian scientist Galileo and other scientists
later proved that the heliocentric model was correct.
• Figure 2 Andreas Cellarius drew these maps of
the geocentric model (left) and heliocentric
model (right) in the 1660s.
Where does Earth appear in each diagram?
Check your UNDERSTANDING!
Check your UNDERSTANDING!
Models of the Solar System
How are the geocentric and heliocentric models of
the solar system different?
In a geocentric model, Earth is stationary while
objects in the sky move around it.
In a heliocentric model, Earth and the other planets
revolve around the sun.
What do you see?
• As Earth rotates, it seems that we are stationary and all of
the objects in the sky are spinning around us.
• The northern stars appear to circle around the North Star
because Earth’s axis points toward a spot in the sky close
to that star.
The apparent motions of
the sun, moon, and stars
result from Earth’s daily
rotation on its axis.
Planetary Orbits
• What keeps the planets in orbit around the sun?
Gravity and inertia combine to keep the planets in orbit
around the sun.
INERTIA
Newton’s first law of motion states that an object in
motion continues to move in a straight line at a constant
speed unless acted upon by a force.
 This property of matter is known as inertia.
GRAVITY
Newton realized that the sun must be exerting a
gravitational force on the planets that keeps them in
orbit.
Johannes Kepler
*discovered that the orbit of a planet
around the sun is not a circle, but an
ellipse.
•The plane of Earth’s
orbit is called the
ecliptic plane.
• An ellipse looks like an oval, or a circle
that has been stretched out along
one axis. Most planets’ orbits are
nearly circular, and so are only slightly
elliptical.
What bodies make up the solar
system?
• Name them…
The ancients knew of six planets. Three
more planets were discovered with the aid
of telescopes:
• Uranus in 1781
• Neptune in 1846
• Pluto in 1930
• (Pluto was later reclassified as a dwarf planet.)
9 Planets
Mercury
Venus
Earth
Mars
Jupiter
Saturn
Uranus
Neptune
Pluto
Remember the mnemonic device for this is:
My
very
educated
mother
just
served
us
Nachos
plain.
Components of the Solar System
• Our solar system consists of:
– Sun
– Planets
• their moons
– Variety of smaller objects that mostly revolve in
the same plane around the sun.
What is a Moon?
Except for Mercury and Venus, all of the planets
have moons.
A moon is a relatively small natural body in
space that revolves around a planet.
Jupiter has 50 moons! The most well-known are Io
(pronounced eye-oh), Europa, and Callisto. Jupiter also has the
biggest moon in our solar system, Ganymede.
These moons are so big you can see them with just a pair of
binoculars.
These moons are so big you can see them with just a pair of binoculars.
• Ganymede is 5262.4 km, or 0.413 Earths wide,
making it a little larger than the Earth's moon.
It is the largest of Jupiter's moons — in fact it
is the largest moon in the solar system.
What is the difference between a sun
and a planet?
• …then how can we see the other planets?
The sun’s mass is about 750 times greater than the
mass of the rest of the solar system combined.
• It is all relative…
SmartStarter – Planets’ Relative Size
• List the planets from smallest to largest…TWICE
• Make 2 attempts:
1. Do the best you can from memory
2. Use your Planet table and/or text book to write them in
the correct order for sure this time
Pla
the planets from
smallest to largest
Distances between objects in the solar system
= much larger than distances on Earth.
• Astronomers often use astronomical units to
describe distances within the solar system.
• One astronomical unit (AU) equals the
average distance from Earth to the sun—
149,598,000 kilometers.
At its closest point, Pluto is only 29 astronomical
units from the Sun
(4.4 billion km or 2.75 billion miles).
Exploring the Solar System
How is the solar system being explored today?
Modern technology, including complex telescopes,
piloted spacecraft, and space probes, has allowed
scientists to explore the solar system.
EXPLORING THE SOLAR SYSTEM
• First Rockets … first rockets powerful enough to escape
Earth’s atmosphere and enter space were developed in the
1940s and 1950s.
• Travel to the Moon… On July 20, 1969,Neil Armstrong,
commander of the Apollo 11 spacecraft, became the first
person to set foot on the moon.
• Recent Missions… Scientists have gathered much
new information about various planets and moons.
• A space probe is an unpiloted vehicle that carries scientific
instruments into space and transmits information back to
Earth.
• The Hubble Space Telescope has also provided many new
views of the solar system and beyond.
• Space Shuttle - reusable space vehicle that is
launched like a rocket but lands like an airplane
• International Space Station - permanent
laboratory designed for research in space.
6 Question KAHOOT
25.1 Assessment Questions
1. What two factors combine to keep the planets in orbit
around the sun?
a.
b.
c.
d.
gravity and centripetal force
gravity and kinetic energy
gravity and solar wind
gravity and inertia
Assessment Questions
1. What two factors combine to keep the planets in orbit
around the sun?
a.
b.
c.
d.
gravity and centripetal force
gravity and kinetic energy
gravity and solar wind
gravity and inertia
ANS:
D
25.1 Assessment Questions
2. Which planet has the largest moon relative to the size
of the planet?
a.
b.
c.
d.
Earth
Mars
Jupiter
Saturn
Assessment Questions
2. Which planet has the largest moon relative to the size
of the planet?
a.
b.
c.
d.
Earth
Mars
Jupiter
Saturn
ANS:
A
25.1 Assessment Questions
3. What is a space probe?
a. a space mission piloted by humans, such as the International
Space Station
b. a permanent settlement on the moon or on another planet
c. a telescope or other instrument that studies space from an
orbit around Earth
d. an unpiloted vehicle that carries instruments into space
Assessment Questions
3. What is a space probe?
a. a space mission piloted by humans, such as the International
Space Station
b. a permanent settlement on the moon or on another planet
c. a telescope or other instrument that studies space from an
orbit around Earth
d. an unpiloted vehicle that carries instruments into space
ANS:
D
25.1 Assessment Questions
4. In a heliocentric model, Earth is at the center of the
universe, and the sun, moon, and stars move around it.
True
False
Assessment Questions
1. In a heliocentric model, Earth is at the center of the
universe, and the sun, moon, and stars move around it.
True
False
ANS:
F, geocentric
25.2 THE EARTH-MOON SYSTEM
• What is wrong with this picture?
The earths orbit is not a circle…it is an_____________.
• Relative size?
Characteristics of Earth’s Moon
• Atmosphere
– Temperature variation
• Maria, highlands, craters
Formation of the Moon
The moon is thought to have formed in a
spectacular collision between the early Earth and
a Mars-sized object.
Phases of the Moon
Two different views of the phases of the moon
are shown in this diagram.
Eclipses
• Solar Eclipse
• Lunar Eclipse
Eclipses
Eclipses occur only at the new moon or the full moon.
Tides on Earth
A. During spring tides, the pulls of the moon and
sun add together.
B. During neap tides, the moon and sun pull
Earth and its oceans at right angles.
25.2 Assessment Questions
1. Why do temperatures on the moon’s surface vary
greatly?
a. There is no gravity on the moon.
b. The moon orbits about Earth.
c. The uneven, rocky surface of the moon creates large shadow
regions.
d. There is no atmosphere on the moon.
Assessment Questions
1. Why do temperatures on the moon’s surface vary
greatly?
a. There is no gravity on the moon.
b. The moon orbits about Earth.
c. The uneven, rocky surface of the moon creates large shadow
regions.
d. There is no atmosphere on the moon.
ANS:
D
25.2 Assessment Questions
2. What are the round impact depressions that cover
much of the moon’s surface?
a.
b.
c.
d.
maria
craters
lakebeds
meteoroids
Assessment Questions
2. What are the round impact depressions that cover
much of the moon’s surface?
a.
b.
c.
d.
maria
craters
lakebeds
meteoroids
ANS:
B
25.2 Assessment Questions
3. What hypothesis about the formation of the moon is supported
by much of the data currently available?
a.
b.
c.
d.
The moon was a large asteroid captured by Earth’s gravity.
The moon formed when a planet-sized body collided with Earth.
Internal stresses caused the early Earth to split into the moon and Earth.
Earth and the moon formed together from a planetary nebula.
Assessment Questions
3. What hypothesis about the formation of the moon is supported
by much of the data currently available?
a.
b.
c.
d.
The moon was a large asteroid captured by Earth’s gravity.
The moon formed when a planet-sized body collided with Earth.
Internal stresses caused the early Earth to split into the moon and Earth.
Earth and the moon formed together from a planetary nebula.
ANS:
B
25.2 Assessment Questions
4. A lunar eclipse can occur when the moon is between
the sun and Earth.
True
False
Assessment Questions
4. A lunar eclipse can occur when the moon is between
the sun and Earth.
True
False
ANS:
F, solar eclipse
25.3 INNER Solar System
SMART STARTER
What characteristics differ between the inner
and outer planets?
Bonus: What is wrong with this picture?
Characteristics of the Inner Planets
- MVEM • Small
• Dense
• Rocky
Dense – Show me the DATA!
Small
Relative size of Terrestrial
planets (and Pluto) 
 Relative size of all
planets
Rocky Terra
• Terrestrial Planets
– similar to Earth’s (“Terra”) structure
– Rocky surface
– Crust - Mantle - Iron Core
Planets PPT Slide Project
Mercury
Venus
Earth
Mars
Asteroids (ABC)
25.4 OUTER Planets
Gas giants….and Pluto
Jupiter
Saturn
Uranus
Neptune
Kuiper Belt
Pluto… Planet OR Dwarf Planet
• Dwarf Planets = too small to be a planet
• Planet (according to the International
Astronomical Union)
– In orbit around the sun
– Enough gravity to be round
– Clear its orbit of smaller objects
• (Dwarf planets’ gravity are not sufficient to do this…)
25.5 Origin of our Solar System
• Nebular Theory
Formation of the Solar System
Any theory to describe the formation of our Solar System
must adhere to these facts:
1.
2.
3.
4.
5.
6.
7.
8.
9.
Each planet is isolated in space
The orbits are nearly circular
The orbits of the planets all lie in roughly the same plane
The direction they orbit around the Sun is the same as the
Sun’s rotation on its axis
The direction most planets rotate on their axes is the same as
that for the Sun
The direction of a planet’s moon orbits is the same as that
planet’s direction of rotation
The Terrestrial planets are very different from the Jovian
planets
Asteroids are different from both types of planets
Comets are icy fragments that don’t orbit in the ecliptic plane
Nebular Theory for Solar System formation
Our sun and the planets began from a cloud of dust and gas (nebula)
As the cloud contracts under its own
gravity, the Sun is formed at the
center.
The cloud starts to spin and the
smaller it contracts, the faster it spins.
Conservation of angular momentum
Cloud forms a flattened, pancake shape.
We’ve seen these disks around other young stars!
Beta Pictoris
Conservation of Angular Momentum
Angular momentum
 mass  rotation rate
 radius2
Condensation Theory for Planet Formation
The gas in the flattened nebula would never eventually
clump together to form planets.
Interstellar dust (grain-size particles) lies between stars remnants of old, dead stars.
These dust grains form
condensation nuclei other atoms attach to
them to start the
“collapsing” process to
form the planets in the
gas cloud.
What happened next…..
A flattened solar nebula disk exists
after cloud spins and contracts
Condensation nuclei form clumps
that grow into moon-size
planetesimals
Solar wind from star formation (Sun
forming) blow out the rest of the gas
Planetesimals collide and grow
Planetesimals form the basic planets
over hundred million years
Why the difference between inner and outer planets?
TEMPERATURE!
•Rocky inner planets: The
type of the material that
condensed out of the nebular
cloud at these higher
temperatures was rocky in
nature.
•Gaseous, Bigger outer
planets: Both rock and gas
could condense out of the
cloud at lower temperatures
where these planets formed.
Why are they gaseous? - gas is present
Why are they bigger? - accretion onto the planet starts sooner
because they are further from the Sun, less effected by solar wind
Assignment: Read 25.5
• Respond to :
• Write a paragraph or more explaining
• 1, why the terrestrial planets formed mostly from metal
and rock, and not hydrogen and helium like the gas
giants,
•
• 2 - explain the nebular theory and how our solar system
formed.
•
• 3- explain why all of the planets revolve around the sun
• within the same plane and in the same direction.