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UNIT ONE IN-CLASS NOTES
8/21
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objects in space
movement of objects in space
Astronomy is the scientific study of the universe and everything inside of it & what is contains
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Science is a progress report & is constantly changing and science is an ongoing process
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What we know and how we learn it
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A mnemonic to remember the steps in a simplified version of the scientific method is :
People : problem
On : observations
Hairy : hypothesis
educated possible solution; educated because of the observations
Elephants : experiments
Always : analysis
Cry : conclusions
In 2006, Pluto got demoted and is not a planet anymore
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8/23
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What is a unit?
o The standard sizes we are comparing too that everybody agrees on
Units of length
o 1 meter=5280 feet
o 1 foot=12 inches
Metric units
smallest to largest
o Nanometer
10^-9
o Micrometer
10^6
o Millimeter
10^-3
o Centimeter
10^-1
o 1 meter
m
o 1 kilometer
km
o Megameter
= 1 million km
o Gigameter
=10^9
o Terameter
=10^12
trillions
Solar system = everything that belongs to sol, the sun
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Like the eight planets and 5 dwarfs
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184 moons
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galaxy= stars bound together by gravity orbiting a common center of gas
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We get around 250 billion stars
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called island universes
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There is only one that we know of
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Our universe is
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The big bang is the start of the universe
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Create clusters called filaments and walls around voids
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49 x 10^8 km
o Used to measure things in the solar system
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Scale 10 cm= 1 AU
The speed of light is constant
Distance = speed X time
Units must cancel to do multiplication, so you have to convert
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5 times in a second
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5
Other sciences, you can see it in real time and you can touch the other sciences but in space, we
can’t see the sky as it is today
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8/28
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If a hypothesis always worked multiply times, it becomes a theory
A theory has been tested and it works
model: a description of nature
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9999% empty
Everything is made of atoms & atoms can be taken apart
Atoms
o Protons
o Neutrons
o Electrons
Plasma is an ionized gas
the atoms are charged
The universe started with the Big Bang
The Big Bang happened January 1st
The ancient Greeks and romans thought the earth was the center of the universe
o They thought the sky was a ball and turned around the earth once a day
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It’s the earth that’s spinning
The earth orbits the sun in 365
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The earth moves eastward against the stars
Some effects of the motion around the sun are that we see different stars in difference seasons
The sun moves around 1 degree per day around the stars
o That has consequences when the sun sets

8/30
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Globe is a model, the celestial sphere is a concept
Earth in the middle of a model is geocentric cosmology
The Earth rotates and revolves around the sun
It takes 24 hours for the Earth to spin
The earth spins toward the east, makes the people disappear towards the west
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Revolution
• Going around a point in space or object
• The earth is revolving around the sun
• The earth is rotating
• Takes a year for the earth to go around the sun, it’s not equal to a year but it’s shorter
because the earth wobbles
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Dayton’s latitude is 40 degrees because that’s where we are on the globe
At noon, you must face south to see it
• The shadow will be pointing north
The sun is never over head in Dayton
Angles
• Separation between two intersecting lines
• 360 degrees in a full circle
• Zenith and horizon is 90 degrees, ¼ of a circle
• Angular separation = one of the units to say how big something is
• The distance between two objects
• Angular size is one way we use angles
• The size of an object
• Tilt: angle between our rotational axis and perpendicular
• Coordinates
• Coordinates are also angles
• 1 degree= 60’ (x’= minutes)
• 60’ = 60” (x”=seconds)
• 3,600” in an hour/degree
What angle does the sun appear to travel along the ecliptic every day?
• The sun moves about one degree everyday
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360 degrees is 24 hour
• One hour, the Earth spins through 15 degrees
• In 60 mins, the Earth will spin another 15”
• In one degree, the difference is four minutes
• The actually time it takes for the Earth to spin once is four minutes short of the typical 24
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These stars orbit the center of the galaxy and move because the Earth wobbles
The word planet means “wanderer” because the planets moved behind the stars
• The Greeks thought earth was not a planet because they were standing on it
Each of the day of week is named after a planet and the planets are named after the Greek gods,
like hercules and Neptune
We use the Anglo saxon names for the week names
• Sunday-for the sun, sol
• To the ancient Greeks, the sun and the moon were planets
• Monday - moon lunda
• Tuesday- from mars
• Wednesday -mercury
• Thursday- Jupiter
• Friday-Venus - friga
• Saturday-satum
• 7 days of the week because there were 7 planets to the Greeks and romans
Asterism - pattern of stars
Out of the 3000 stars you can see, only 300 have word names
Constellation: area or region of the sky
Take the sky, cut it into pieces and each piece is a constellation
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All boundaries= there are no boundaries
We connect the bright stars to make pictures, everything in a boundary in the sky, are in a
constellation
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On the earth we have longitude and latitude
Longitudes is east and west, 360 degrees each way so 720 is the most we can go
Latitude is north and south
The international date lines
• A line between Asian and Europe and north America
• When you step over it, you go one day forward (going west) or one day behind it (going
east)
• Europe and Asia is ahead of us
• We are the last ones to get anything
• At the same time, it can be two different dates
The poles don’t have longitude coordinates
Right ascension is the angle measured eastward from there the ecliptics and CE cross on the first
day of spring
The path of the sun= the ecliptic
The seasons depend on the sun
The Celestial equator → right above the earth’s equator
When the sun is going north - vernal equinox
start of spring
• Around March 20th
when the sun is going south → autumnal equinox
starts of Autumn
• Around September 21st
Summer solstice - the highest the sun is in the sky, around June 21
Winter solstice - the lowest the sun is in the sky, around December 21

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Mayans had a calendar that was based on Venus
• They had long cycles
• They thought the earth was going to end in 2012 but it was just their first cycle ending
The solstices are when the sun is as far away from the equator as it gets
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5 tilt
Tropic circles
• Tropic of cancer and tropic of Capricorn are the highest and lowest the sun will reach at
the solstices
• Summer solstices - tropic of cancer
• Winter solstice- tropic of Capricorn
Arctic circle
• Winter solstice - 24 hours of dark
Antarctic
• Winter solstice - 24 hours of light

9/6
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Light pollution is wasted
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The sun’s motion is in between the cardinal directions
We lose daylight as we get closer to winter
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5 mean solar days, we don’t have 29
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) must be evenly divisible by 400
We use the Gregorian calendar
• Pope Gregory the 14th did calendar reform
• The extra days has caused the VE to drift and spring wasn’t starting on the correct day
When is Easter → first Sunday after the first moon, after the VE?
• Easter would show up late if they didn’t change the calendar
Study about pope Gregory

9/11
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Phases of the moon and eclipses
Closest neighbor to earth
The moon is orbiting the Earth
The moon is naturally occurring satellite
Moon preliminaries
We never see the full moon
• We always see just one side of the moon
Synchronous rotation
• Set things equal, one spin = one orbit

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We call the side of the moon that we can’t see from here is called the ‘far side’ or the ‘other side’
or the ‘back side’
There are 8 phases of the moon
Waxing means growing and waning means shrinking
Waxing phases are visible during the evening
Waning phases are visible during the morning
Moon is only seen for 12 hours of the day
The new moon is up during the day at noon
Age of moon - age of the phase the moon is in
Harvest moon - first full moon closest to the autumnal equinox, can be before or after
• Normally in September but can be in October
Full moon is bright enough for farmers to harvest during the nighttime
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Perigee - when the moon is closest to the earth
Apogee- when the moon is the furthest from the earth
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3 days
The sidereal month is 27
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• Partial - if the moon gets the earth on the edge
• Penumbral - if the moon misses the earth entirely
Red light from the sun can make the moon red

9/13
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Astronomy is the oldest science
People have been looking at stars ever since they could look at stars

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9/18

Archeoastronomy- the study of how ancient cultures used astronomy to develop systems of time
and the calendar
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During Aristotle’s time, they did not have scientist, they have philosophers
Phases of the moon are not caused by the earth’s shadow
• The earth’s shadow is never straight
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Uniform circular motion - perfect circles at constant speeds
People thought the heaven had be perfect, so they lived a perfect life so that they would go to
heaven
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Eratosthenes measured the side of the earth
He found that the sun hit the Earth at different points, so he made an equation
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Hipparchus looked at the stars
Smaller the number, the brighter the object is how we use our magnitude scale for stars today
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The Earth orbits the sun, spins on an axis and wobbles
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Claudius Ptolemy made a model of the universe from Hipparchus and Aristotle's information
They thought the Earth stood still and the celestial sphere was going counterclockwise, and the
sun and moon were in between the sphere and earth and were going clockwork
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Claudius Ptolemy invented epicycle and deferent cycles
He wrote a book but the great library in Alexandria was burned so it was lost
Almagest means the greatest, he had in that book all the cycles and all the speeds
They used to believe in astrology
Astrology is not science
• Started over 2,000 years ago when they believed the god had an influence on your life
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• He made a simple version
• Wrote a book
• The book was published the year he died
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Books make people think and question if he could be right or not
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Put under house arrest, 70 years old and blind from looking at the sun
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His daughters were nuns and he was buried by one of his daughters
Sir Isaac Newton
o He was too busy to go to his own wedding
o Discovered the universal law of gravitation
o An apple hit him on the head, and he discovered gravity
o Invented calculus, the other one was a German
o Came up with three laws of motion
Gravity is an attractive force; it’s always pulling never pushing
A force - push or pull
Weight - pull of gravity
Weight if a force
Force’s units are newton
Only four shapes gravity can be:
o Ellipses and circles will come back, but hyperbola and parabola will not come back
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9/25/18
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Light is electromagnetic radiation

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Radioactivity is a reaction that shoots out particles
James clerk Maxwell, studies electricity and magnetism
Wanted to study charges that moved
Developed equations
The attraction between opposite charges is responsible for chemical bonding
Field - how objects interact if they’re not touching
Earth sets up a gravitational field and the moon is inside of the field, so the moon is
interacting in the field, not the earth
Sound is compression wave
o Requires a medium to travel through
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Trough to trough or crest to crest is counted as one wavelength
We use the Greek letter, lambda for symbolize wavelength
The speed of light is 3
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Double one, cut the other in half
o Wavelength and frequency are inversely proportional
Between the earth and sun is a vacuum
o Light will travel through empty space
o Sound cannot travel through the vacuum thought; it requires something to
compress
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You go twice as far, it’s going to be 4 times dimmer
Spectrum - to spread something out
With light, when we say spectrum, we’re going to spread the light out
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o Humans radiate infrared

9/27/18
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Purple is the pigment and violet are the light that it’s reflecting because the human eye
cannot see violet
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In emission, dropping to a lower
lever and giving off energy
The doppler effect
o How it’s moving, waves get stretched as they’re moving away and scrunched
when moving towards you
o Caused by the motion of the object relative to the observer
o Can be used to measure the speed of objects in space, used for radial velocity
Toward you, wavelength is compressed, and frequency is higher, blue shifted
Away is redshifted
Radial velocity is like spokes in a wheel
Motion that doesn’t change its distance from you is circular
The type of motion that DOES NOT cause a doppler effect is a tangent line - tangential
velocity
Speed of the object / speed of the wave = change of the wavelength/ wavelength is rest
o Change in wavelength / wavelength in lab
Negative is toward, positive is away
Light can be brought to a focus in two ways
o Bounding and bending
Bouncing is reflection, bending is refraction
We use refraction to bring light to a point
o We need to use a convex lenses
For a lenses
o How wide is it and what the focal length is
Angle of incidence is equal to the angle of reflection

10/4/18
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Images are inverted, so pictures are backwards
Least important thing a telescope does is magnify
m= f
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Objective / fl
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▪ Every asteroid is orbiting the sun
▪ Minor planet is what we used to call asteroids
o Must have enough mass to be pulled into a sphere
▪ Must be round
o A planet must have to clear it’s orbital space
Physical
o Size
o Mass
o Density
o Composition
Terrestrial is earth like
o Mercury, Venus, ,earth and mars
Jovian planets are Jupiter like
o Jupiter, Saturn, uranus and neptune
o Can be called giant planets
Mass is stuff and measured in either grams or kilograms
Volume is 3 dimensional space
o L x w he
o Centimeters or meters cubed
Density of water is 1 g/cm^3
o Water is used to set the scale

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o 1 gram per unit density
Rock is more dense because it sinks if it’s in water
o Rock is anywhere from 2 -3 g/cm^3
Density tells us what types of materials things are made of
Somewhere inside of earth is denser than rock and water
o Which leads us to believe we have an iron core
Mercury is the most iron rich planet of the solar system
Saturn is the least dense planet because it has little mass in a large size
Neptune’s surface is frozen, no gaseous atmosphere the surface is slush, a big slush
ball

10/11/18
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7 large moons
o Earths
o Io
o Europa
o Ganymede
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Calisto
▪ 4 Galilean moons of jupiter -what he saw through his telescope
o Titan - with Saturn
o Triton - with Neptune
Large moons are moons because they orbit a planet, not the sun
o Size is not something that makes something a planet
Asteroids are very small, only about km wide
o Left overs from the terrestrial planets
Comets are made of ice and dust
o Dirty snowballs of the universe
o Left over from the Jovian planets
o Orbits are eccentric
o Keilter belt objects
▪ When they get kicked out, they become comets
Earth formed from comets
Comets vaporize as they get closer to the sun
Dust grains between the planets
Small bits of dust -meteoroids
Meteor Showers are related to comets
Neon and helium are noble gasses
o They are special
o Do not bond to make molecules
o Anti-social
Hydrogen is the most common
Water, ammonia, and methane are ices
o Very common
Gold is hard to make
o It’s made by merging neutron stars which does not happen often
o Only way it’s made
Hydrogen and helium were made in the big bang
You cannot have liquids in space because there’s not enough pressure for them to
exist
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Two forms of heat
o Collisions
o Naturally occurring radioactive decay
radioactive decay is still heating the inside of the earth
Differentiation is what gives our planets layers
Asteroids are the oldest rocks in the solar system
We date meteorites to get the age of the solar system
Venus has the hottest because it’s atmosphere has trapped heat
o The greenhouse effect, how we learned about the greenhouse effect
Mercury has the greatest range of temp
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2 km/second - 25,000 miles per hour
Gas - look at the temperature
o Give the average speed of the gas
o Hotter it is, the faster it will go
Absolute temp is proportional to kinetic energy
o Kinetic energy depends on the mass
Geological activity can e
Voyager found the dust ring
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Saturn only has c,b,a (3 rings) visbile from earth
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o Cassini division between the a and b ring (c closest to the planet)
There’s a tiny moon in the gap
Moonlets are particles in the rings
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F, g, e going from planet outwards
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Mimas is the death star
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There are moons on both sides of the f ring
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As one of the moons go at differnet speeds, it makes the ring particles move
back and forth due to the energy volt and loss
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o Has a moon on either side of the ring and gives the ring a unique shape
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There’s a moon that’s imbedded in the e ring
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Something is causing the moon
to shoot ice particle in space and they’re getting left behind to create a ring
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Saturn’s rings are thin
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20 meters, from top to bottom of a ring
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Not all the asteroid's lay in the asteroid belt
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There’s a lot of asses in jupiter's orbit
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o Trojan asses if they get caught in there
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o Runs 2-3 au’s from the sun
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Kirkwood gaps are regions where there are fewer asses because jupiter would push
it down in a lower orbit
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If things get too close to jupiter, it puts the object in a short orbit
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Unit Four - Astronomy Notes
11/13/18
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Venus’s tilt is 177 degrees, it’s the only upside down planet
Uranus’s rotation is sideways
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They are common because they were made with the common elements
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You had ices and rocks to build your cores from, once you build your cores, you can
hang on to the gasses
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o Might get hit by an asteroid
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o It did the grand tour
▪ Replies on the planets being aligned properly
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o They line up every 175 years for the grand tour
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Earth to jupiter was five years
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Voyager one and two are still working, they’re past the sun’s magnetic dominance,
where the sun’s magnetic field merges into the background - in the scattered disk
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o Jupiter gave it energy and made it go faster
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Years to decades to get the jovians, it takes hours to get signals from the jovians
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Jupiter is the biggest and it takes the longest to cool off
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Jupiter has a red spot, it’s a storm
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o It’s been there since we’ve been able to see the planets, but it’s shrinking
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Neptune is blue and it has clouds
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Cloud patterns are driven by internal heat and convection
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They crashed Galileo into Jupiter because we didn’t want it to hit Europa, Jupiter’s
moon, because the moon has a liquid water ocean crust
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We did the same thing with Cassini, bopped it into saturn
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Uses three solar panels, solar
powered
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It’s good at absorbing
red light, showing blue
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Jupiter is a radio source
By studying the radio waves, we know how fast it spins
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Solid body rotation - periods are the same, speed is not
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-- differential
rotation
Jupiter almost has no tilt, so no reasons
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Uranus’s moons names are from shakespeare and pope plays
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o 42 years in dark and 42 years in light
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o Density is 35 g per cubic centimeter, very dense
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All jovian planets have magnetic fields
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o They have internal energy sources, they're all different
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Neptune is contracting, converts gravitational energy into heat
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Saturn is the last dense, low gravitational pull
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Jupiter has the longest lived storm
Has the most moons
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Uranus is tilted sideways, most extreme seasons
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They’re not aligned with their spin axis and not centered
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Helium falling as rain in saturn
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Neptune has gravity by contracting
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- has the biggest bulge - oblateness - how non spherical
something is
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Things that are spinning have a bulge
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o Thin atmosphere
o Lower gravity
o Expands outwards
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If it moves against the background of stars - it’s a planet
Herschel saw it’s orbit and realized it was a planet
Ura
o The moon always keep the same face turned towards the Earth
o Dark side - back side of the moon
9-6-18 Ch 4 S 4
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o Solar Eclipse - when the moon’s shadow hits the Earth
o The shadows consist of 2 parts
▪ Umbra - where it’s the darkest
▪ Penumbra - region where it’s the lightest
o The angular side of the moon and sun vary depending on their distances from the Earth
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o If the sun and moon are property aligned, then the moon’s darkest shadow intersects the
ground at a small point on Earth’s surface
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o Partial solar Eclipse - observers on a larger area of Earth's surface who are in the
penumbra (light side ) will only see a part of the sun eclipsed by the moon
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o The average time for an Eclipse is about 7 minutes
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▪ There is a lot of traveling by water and air, you need money
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o During a solar Eclipse, the sky gets so dark that we could see some of the planets and
stars
o corona - sun’s outer atmosphere, consisting of sparse gases that extend for millions of
miles in all directions from the apparent surface of the sun
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o Lunar can take place when the sun, earth and moon are in line
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o Lunar Eclipses can last up to 1 hour and 40 minutes
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o Eclipses can be predicted centuries in advance due to our technology
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• Ch 2 S 2
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▪ Their yearly cycle corresponded with the flooding of the nile river
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Mayan culture madea calendar based on the Venus
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Cosmology - our concept of the cosmos where it came from and it’s origin(s)
Anvicnet’s cosmology included theri beliefs of the heavens and philosophical and
religious symbolisms
Pythagoras said that sphere are perfect forms and therefore, the earth should be a sphere
Greeks said the moon should be a sphere as well
Asistole
▪ Tutor of alexander the great (King of Ancient greek Kingdom)
▪ Describe the moon's phases and how the sun had to be far away
▪ Arguments were that the Earth had to be around because the shadow on the moon
was round and that if the earth was flat everybody would be able to see the stars
but as travelers crossed a curved surface, they saw the stars at angles
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Parallax- the apparent shift in direction of an object as a result of the motion of the
observer

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