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Pick up 2 packets. Draw on the back of your notes packet:. 1. Your picture of the 8 planets orbiting around the sun. What type of solar system is this called? - PowerPoint PPT Presentation
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Pick up 2 packets.Draw on the back of your notes packet: 1. Your picture of the 8 planets
orbiting around the sun. What type of solar system is this called?
2. Your picture of how ancient people must’ve drawn the planets orbiting around Earth. Remember, they had to keep their observations of retrograde motion in mind! What is retrograde motion? What type of solar system is this called?
History of our Knowledge of the Solar System
EARLY IDEAS GEOCENTRIC UNIVERSE
Early Astronomers Separated Stars from
Planets▪ Planets movements
can be tracked because stars do not move.
Ptolmey: Geocentric Universe▪ Earth is the center of
the universe.▪ All the planets and
the Sun revolve around the Earth
Geocentric Model of the UniversePROBLEMS
1). Retrograde Motion A sudden
change in planetary motion
Planets switch from moving East to moving West
Very hard problem to solve
Scientists began looking for a better model of the universe/solar system.
http://www.youtube.com/watch?v=ln1fHZvRr8o
Retrograde Motion SolvedCOPERNICUS RETROGRADE MOTION
EXPLAINED
In 1543, he suggested a heliocentric model of the universe Sun centered Earth and all
other planets orbit the Sun
Why do we see planets moving backwards? Inner planets move
faster then outer planets around the Sun.
Earth will “pass” a slower moving planet▪ This planet appears
to move backward temporarily.
What is Eccentricity
ECCENTRICITY DETAILS
What is eccentricity? Ratio of distance
between the foci to the major axis.
Change in distance from the focus points; such as distance of a planet from the Sun. Planets are not always
the same distance away from the Sun.
http://www.youtube.com/watch?v=BIBz_GQDga0
The point in orbit when the planet comes nearest to the Sun = Perihelion
The point in orbit when the planet is farthest from the Sun = Aphelion
Kepler’s Laws
1ST LAW ASTRONOMICAL UNIT
Most planets orbit the Sun in an elliptical shape More oval like Earth being the
exception Earth believed to move
between an elliptical orbit and a circular orbit every 100,000 yrs or so.
Planets orbit while staying centered around 2 points. Sun is one point
How we measure the average distance between the Sun and planets. Sun to Earth = 1
astronomical unit (AU)
Kepler’s Law
Planets sweep out equal areas in equal times.
Perihelion/Aphelion on Earth
Gravity
In the late 16th century early 17th century Galileo was working with gravity.
Performed experiments dropping objects off the Tower of Pisa and rolling balls down inclines
Galileo found Gravity
accelerates the fall of all objects at the same rate.
Air resistance causes lighter objects to fall more slowly.
Gravity
SIR ISAAC NEWTON BASICS
1687 Newton published his theory of universal gravitation. Also called the inverse
square law This theory helped
discover Neptune. Watched Uranus’s
movements▪ Something large was
affecting the movements of the planet.
Two objects attract each other Depends upon
their mass AND the distance between them.
Law
This knowledge of gravity produced the law of universal gravitation.
The larger the objects (m) the stronger the force of gravity between them.
The farther apart the objects (d) the weaker the force of gravity. Distance squared
weakerG = Constant 6.6726 X 10-11
Astronomy: Part 2 Stars
3/7/13
Fact or Fiction
Stars twinkle in the night sky Twinkle: Change in Brightness
Beginning of A Stars Lifecycle 1). Interstellar
Cloud/Nebulae Big Cloud of Gas
and Dust
Once enough gas has collected the nebulae will condense forming a….
2). Protostar: Pre-star
As the protostar continues to condense it will heat up until it hits Critical Mass and…
3). Nuclear fusion begins Now we have a real
main sequence star. ▪ Main Sequence =
Stable
What is a Star?
Star = A cloud of gas, mainly hydrogen and helium with a core so hot and dense that that nuclear fusion can occur. Very Common
Purpose/Jobs 1). Provide Light▪ Heat Energy▪ Warms Planet Earth
2). Nuclear fusion within stars converts light elements into heavier ones
Nuclear Fusion
Create new more complex elements Without these life
would not be able to form
Will continue in a star until no heavier element can be produced Iron is the ultimate
stopping point
Helps balance out the force of gravity trying to act on stars
When fusion stops, gravity will win and cause the star to collapse. This is when a star
begins to die.
Important Star Qualities
Three Main Characteristics1. Brightness/Magnitude
1. Light releasing capacity
2. Color1. Determines Temperature
3. Size1. Determines means of Death
Stars Magnitude/Brightness
MAGNITUDE Tells us how luminous the star
is/ How much energy is being produced in the core
Astronomers rate the magnitude of a star with a scale that gives brighter stars a low number and dim stars a higher number. Each whole number on this
scale is 10 times dimmer than the previous number.
The brightest star the night sky is Sirius. magnitude of -1.46 it is almost 15 times
brighter than a star with a magnitude of zero.
Stars with a magnitude of 8 or more are too dim to see with the naked eye.
Color of Stars Stars are identified by
their color, which indicates their temperature.
They are divided into what are known as spectral classes.
These classes are O, B, A, F, G, K, and M.
Class O stars are the hottest and are blue in color.
The coolest stars are identified as class M and are red in color.
Star Size
Determines the length of a star’s life Large Stars = Burn Out Quickly
Small Stars = Use fuel more slowly▪ Around for much longer periods of time.
Star size also determines the death route a star will take.
The Death of an Average Size Star
Fusion of Hydrogen Stops No longer a main sequence star
Red Giant Large star that is reddish or
orange in color Reaching sizes of over 100 times
the star's original size. Late phase of development in a
star's life ▪ Hydrogen has been exhausted and
Helium is being fused. ▪ This causes the star to collapse,
raising the temperature in the core. ▪ The outer surface of the star expands
and cools, giving it a reddish color. This phase will continue until the
star completely runs out of fuel
Planetary Nebulae When nuclear fusion stops Stars blow away their outer
layer of atmosphere
White Dwarf Remaining core of the star
▪ Present after atmosphere has blown away
Still very hot so it glows white until it cools off
Black Dwarf Cooled off core of a star
Death of A Massive Star Fusion of Hydrogen Stops
No longer a main sequence star
Red Supergiant Extremely large star that is
reddish or orange in color Reaching sizes of over 1000
times the star's original size. Late phase of development in a
star's life ▪ Hydrogen has been exhausted and
Helium is being fused. ▪ This causes the star to collapse,
raising the temperature in the core. ▪ The outer surface of the star expands
and cools, giving it a reddish color. This phase will continue until the
star completely runs out of fuel
Betelgeuse in Orion is an example of a red supergiant star.
Death of A Massive Star Continued Supernova
violent explosion ejects most of its
mass. often briefly
outshines an entire galaxy▪ fade from view
over several weeks or months
Neutron Star If the remaining mass of the star is
about 1.4 times that of our Sun, the core is unable to support itself and it will collapse further to become a neutron star.
The matter inside is compressed so tightly that its atoms are compacted into a dense shell of neutrons.
Black Hole If the remaining mass of the star is
more than about three times that of the Sun, it will collapse so completely that it will literally disappear from the universe.
What is left behind is an intense region of gravity called a black hole.
Planet Types
TERRESTRIAL PLANET GAS PLANET
Inner Four Planets Closest to the Sun Mercury, Venus,
Earth, and Mars
Close to the size of Earth
Solid, Rocky Surfaces
Outer four Planets Farthest from the
Sun Jupiter, Saturn,
Uranus, Neptune
Larger
More Gaseous
Lack Solid Surfaces
How Do Scientists Know How Our Solar System Formed?
Earth Based Studies Use of telescopes
in all wavelengths of the electromagnetic spectrum.
Data From Probes
Scientists Examined 1). Why the
planets are so different.▪ Especially Outer
and Inner Planets 2). Asteroids,
Meteorites, and Comets.
Formation of Our Solar SystemINTERSTELLAR CLOUDS
Huge Clouds of Dust and Gas in Space
Made of Hydrogen and Helium
Form Stars and Planets
These Interstellar Clouds usually look dark because the dust blocks light. Like Smog Stars behind this
cloud can’t shine through it.
Formation of our Solar System
INTERSTELLAR CLOUD
But….Sometimes the light from stars within the cloud causes these interstellar clouds to glow.
Formation of our Solar SystemLOCATION
There are many interstellar clouds found within our Milky Way Galaxy. We look for high
amounts of gas and dust.
When enough gas and dust is present, scientist think these interstellar clouds will condense because of gravity. Can form a star or
planet
Formation of our Solar System
COLLAPSING INTERSTELLAR CLOUD
Cloud begins collapsing slowly.
The smaller it gets the faster it begins to collapse and spin
This spinning motion with eventually form a rotating disk with a very dense center (core).
Formation of our Solar System
Scientist believe that one huge interstellar cloud called the solar nebula formed the Sun and all the planets.
The Sun formed first in the center of this cloud. Fits with why our Sun is
the brightest most dense thing in our solar system.
In the center of the cloud it was the hottest
On the edges of the cloud it was the coldest
Formation of our Solar System
SO WHAT?
This difference in temperature as the solar system cooled caused materials to condense and be located in very narrow regions of the solar system
This is why we see inner planets and outer planets have such different composition.
Development of Planets
Once these materials condense out they begin to collide and stick together.
Keep growing larger until they form planetesimals Objects 100’s of km
in diameter
To produce planets, planetesimals must collide and stick together
Development of PlanetsOUTER PLANET FORMATION
1st planet of the gas to form was Jupiter This is why Jupiter is the
largest. Had the most materials to
build with Then Saturn and the rest
of the gas giants formed▪ Not as large because Jupiter
hogged most of the materials; gas, dust, and ice to make itself.
Leftovers became Moons
Development of PlanetsINNER PLANET FORMATION
Inner planets were forming from the collision of planetesimals. Made of very
different things
Sun took all the gas and floating debris away from the inner planets. Why they are
rocky and dense Why Moons are
rare for inner planets.
Space Rocks 101
ASTEROID
Leftover pieces of Planetesimals
These were never planets
Asteroids can collide and break apart.
Space Rocks 101
METEOROID METEOR
When an asteroid or any space material falls toward Earth and enters Earth’s atmosphere.
The streak of light produced when a meteoroid burns up in Earth’s atmosphere.
Space Rocks 101
METEORITE
When a space object impacts Earth
Occurs when all of the meteoroid does not burn up in Earth’s atmosphere
Meteor Crater: Arizona
Gosses Bluff, Australia
Space Rocks 101
COMETS
Small icy and rocky bodies with a highly eccentric orbit around the Sun.
When Earth is in the way of a comet’s orbit we see a meteor shower