Ch 27 Questions What are some theories about how our solar system began The Nebular Hypothesis solar nebular a rotating cloud of gas and dust from which the sun and planets formed In 1796 French mathematician ID: 392116
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Slide1
The Beginning of Our Solar System
Ch 27Slide2
Questions??
What are some theories about how our solar system began?Slide3
The Nebular Hypothesis
solar nebular
a rotating cloud of gas and dust from which the sun and planets formed
In 1796, French mathematician
Pierre Simon, advanced a hypothesis now known as the
nebular hypothesis.Slide4Slide5
The Nebular Hypothesis
The sun is composed of about 99% of all of the matter that was contained in the solar nebula.
planetesimal
a small body from which a planet originated in the early stages of development of the solar systemSlide6
Nebular Hypothesis
Some planetesimals joined together through collisions and through the force of gravity to form larger bodies called
protoplanets
.
Protoplanets’ gravity attracted other planetesimals, collided, and added their masses to the protoplanetsSlide7
Diagram of Nebular HypothesisSlide8
Nebular Hypothesis
Step 1:The young solar nebula starts to collapse due to gravity.
Step 2:
As it rotates, it flattens and becomes warmer near the center…this is where our sun formed.
Step 3:
Planetesimals form within the swirling diskSlide9
Nebular Hypothesis
Step 4:As planetesimals grow, their gravitational pull increases. Larger planets collect mostly dust and gas.
Step 5:
Small planetesimals hit larger ones and planets begin to grow.
Step 6:
Left over dust and gas leave solar nebula and our solar system is formed!Slide10
The Planets
The Inner Planets
:
Mercury, Venus, Earth, Mars
Smaller, rockier, more dense than outer planets
Contain heavier elements like nickel and iron
The outer Planets
:
Jupiter, Saturn, Uranus and
Neptune
Composed of lighter
elements such as helium, hydrogen
and their ices (water ice,
ammonia ice & methane ice)
Called
gas giants
b/c made
of gas and have low densitySlide11
Pluto – The Different Planet
Farthest and smallest planet
(smaller than Earth’s moon)
Ice ball made of frozen gasses and rocks
Scientist do not believe that Pluto qualifies as a real planet.
Question?? How is Pluto different from the outer planets?
Unlike the other outer planets, Pluto is very small and is composed of rock and frozen gas, instead of thick layers of gases.Slide12
The Formation of Solid Earth
First,
Earth was very hot, then Earth cooled to form three distinct layers
.
Differentiation – denser materials sank to the center and lighter materials were forced to the outer layers.
Center: dense core of iron and nickel
Mantel: surrounds core, think layer of iron &
magnesium rich rock
Crust: outermost layer, less dense, silica rich rockSlide13
Earth’s LayersSlide14
Earth’s Atmosphere
The atmosphere formed because of differentiation.
Earth’s gravity is too weak to hold high concentrations of hydrogen and helium gases and is blown away by solar winds.
Outgassing
Outgassing
formed a new atmosphere as volcanic eruptions released large amounts of gases
The
ozone
formed from remaining oxygen molecules after solar radiation caused ammonia and some water vapor to break down.Slide15
Formation of EarthSlide16
OutgassingSlide17
Earth’s Present Atmosphere
The ozone collected in a high atmospheric layer around Earth and shielded Earth’s surface from the harmful ultraviolet radiation of the sun.
Organisms, such as cyanobacteria and early green plants, could survive in Earth’s early atmosphere by using carbon dioxide during photosynthesis
These organisms produced oxygen as a byproduct of photosynthesis and helped slowly increase the amount of oxygen in the atmosphere.Slide18
Question??
How did green plants contribute to Earth’s present-day atmosphere?
Green plants release free oxygen as part of photosynthesis, which caused the concentration of oxygen gas in the atmosphere to gradually increase.Slide19
Formation of Earth’s Oceans
Were the first oceans fresh water or salt water?
Fresh water
As rain continued to fall, rocks were dissolved into the oceans.
As evaporation occurred, some of the chemicals from the rocks combined to form salts, making the oceans increasingly more salty.Slide20
The Ocean’s Effect on the Atmosphere
The ocean affects global temperature by dissolving carbon dioxide from the atmosphere.
Since Earth’s early atmosphere contained less carbon dioxide than today, Earth’s early climate was probably cooler than the global climate is today.Slide21
Multiple Choice
Small bodies that join to form protoplanets in the early stages of the development of the solar system are A. planets
B. solar nebulas
C. plantesimals
D. gas giants
Chapter
27Slide22
Multiple Choice, continued
Small bodies that join to form protoplanets in the early stages of the development of the solar system are A. planets
B. solar nebulas
C. plantesimals
D. gas giants
Chapter
27Slide23
Multiple Choice, continued
2. Scientists hypothesize that Earth’s first oceans were made of fresh water. How did oceans obtain fresh water?
A. Water vapor in the early atmosphere cooled and fell to Earth as rain.
B. Frozen comets that fell to Earth melted as they traveled through the atmosphere.
C. As soon as icecaps formed, they melted because Earth was still very hot.
D. Early terrestrial organisms exhaled water vapor, which condensed to form fresh water.
Chapter
27Slide24
Multiple Choice, continued
2. Scientists hypothesize that Earth’s first oceans were made of fresh water. How did oceans obtain fresh water?
A. Water vapor in the early atmosphere cooled and fell to Earth as rain.
B. Frozen comets that fell to Earth melted as they traveled through the atmosphere.
C. As soon as icecaps formed, they melted because Earth was still very hot.
D. Early terrestrial organisms exhaled water vapor, which condensed to form fresh water.
Chapter
27Slide25
Multiple Choice, continued
The original atmosphere of Earth consisted of A. nitrogen and oxygen gases
B. helium and hydrogen gases
C. ozone and ammonia gases
D. oxygen and carbon dioxide gases
Chapter
27Slide26
Multiple Choice, continued
The original atmosphere of Earth consisted of A. nitrogen and oxygen gases
B. helium and hydrogen gases
C. ozone and ammonia gases
D. oxygen and carbon dioxide gases
Chapter
27Slide27
Multiple Choice, continued
Scientists think that the core of Earth is made of molten F. iron and nickel
G. nickel and magnesium
H. silicon and nickel
I. iron and silicon
Chapter
27Slide28
Multiple Choice, continued
Scientists think that the core of Earth is made of molten F. iron and nickel
G. nickel and magnesium
H. silicon and nickel
I. iron and silicon
Chapter
27Slide29
Short Response
6. What four planets make up the group known as the inner planets?
Chapter
27Slide30
Early Models of the Solar System
Geocentric = ?
Earth centered solar system
Aristotle proposed this idea
Sun, stars and planets
revolved around the EarthSlide31
Claudius Ptolemy
Proposed changes to Aristotle’s model
Thought that planets moved in small circles, called
epicycles
, as they revolved around the Earth
.
Explained why some planets seemed to move backwards at times: retrograde motion.
The word
”retrograde”
derives from the Latin words “
retro”
meaning backwards, and “
gradus”
, meaning stepSlide32
A circular orbit in a circular orbit.
This satisfied the Greek’s idea
of an Earth centered Universe
and the idea that the motion of
the heavenly bodies moved in
perfect circles.Slide33
Early Models of the Solar System
Heliocentric = ?Sun centered solar system
Copernicus proposed this idea
Planets revolved around the
sun but at different speeds
and distances from the sun.Slide34
Kepler’s Laws
Law of Ellipses
eccentricity -
the degree of elongation of an elliptical orbit
(symbol,
e
)
The
law of ellipses
states that each planet orbits the sun in a path called an ellipse, not in a circle.Slide35
Kepler’s Laws
Law of Equal Areas
The
law of equal areas
describes the speed at which objects travel at different points in their orbit
. It states that
equal areas are covered in equal amounts of time
as an object orbits the sun.
When the object is near the sun, it moves relatively rapidly. When the object is far from the sun, it moves relatively slowly.Slide36
Law of Equal AreasSlide37
Kepler’s Laws
Law of Periods
orbital period
-
the time required for a body to complete a single orbit
The
law of periods
describes the relationship between the average distance of a planet from the sun and the orbital period of the planetSlide38
Kepler’s Third Law
The mathematical equation,
K
x
a
3
=
p
2
, where
K
is a constant, describes this relationship.
When distance is measured in astronomical units (AU) and the period is measured in Earth years,
K
= 1 and
a
3
=
p
2
.
a = average distance from the sun
p = periodSlide39
Example:
Jupiter has an orbital period of 11.9 Earth years.
Find the average distance.
a³ = p²
a³ = (11.9)²
a³ = 142
a = 5.2 AUSlide40
Kepler’s Laws explained by Newton
:
inertia
the tendency of an object to resist being moved or, if the object is moving, to resist a change in speed or direction until an outside force acts on the object
Who discovered gravity?
Newton
Gravity - an attractive force that exists between any two objects in the universe.
While gravity pulls an object towards the sun, inertia keeps the object moving forward in a straight line. This forms the ellipse of a stable orbit
.
The gravitational pull is strongest closer to the sun, and weakest further from the sun.Slide41
Law of Inertia:Slide42
QUIZ!!!!!
A planet moves relatively slower when it is farther from the sun than it does when it is closer to the sun.
True or False?
TrueSlide43
QUIZ!!!
Kepler’s first law states that each planet orbits the sun, not in a circle, but in an ellipse.
True or False??
TrueSlide44
QUIZ!!!
Kepler’s third law states that the square of the average distance of a planet from the sun is proportional to the cube of the orbital period.
True of False
False