unit 7 astronomy
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Name:______________________ Period:____. Unit 7 Astronomy. Focus Questions. ___1. How and why do stars move through our sky? ___2. Explain the apparent motion of the Sun through our sky? How does the path of the Sun change throughout the year? ___3. Why do we have seasons? - PowerPoint PPT PresentationTRANSCRIPT
Unit 7Astronomy
Name:______________________ Period:____
Focus Questions___1. How and why do stars move through our sky?
___2. Explain the apparent motion of the Sun through our sky? How does the path of the Sun change throughout the year?
___3. Why do we have seasons?
___4. How does latitude and the angle of the Sun affect daylight hours?
___5. Explain why we see the Moon’s phases?
___6. Explain what happens during a lunar and solar eclipse?
___7. Why do we have tides?
___8. What is the true shape of an orbit and what are the parts of an orbit?What is the equation to measure an orbit’s eccentricity?
___9. Explain what the HR diagram is used for? Explain our Sun’s properties by using the HR diagram.
___10. Describe galaxies and what theory is used to describe the formation of the universe? How can we tell if celestial objects are moving towards or away from us?
A. Celestial Observations1. The objects in the sky collectively are called _________________________________________
--They include ____________________________________
--They appear to move in the sky ______________________
--The path they appear to take is in the shape of _______________
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celestial
The Sun, planets, moons, stars, etc.
From East to West
An arc
objects
Celestial Sphere
2. All objects in the night sky appear to travel in a set path around ____________which is located almost directly over the North Pole of Earth.
Polaris
Many of the stars form specific patterns, or ________________. Some of these never go below the horizon in New York State. Instead, they appear to circle Polaris over the course of a night.
This is about a ten hour time exposure of the northern sky. The arcs are the paths of the stars circling the North Star (Polaris) in the center.
These stars can be seen year-round in the northern sky although their exact location each night will vary throughout the year.
Orion
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constellations
Other stars appear to move throughout the night from east to west.
These are trails of stars that are further to the south in our night sky. Their trails appear almost straight.
The constellations and the stars that make them up also appear in different locations throughout the year.
All celestial objects appear to move at a rate of 15 degrees per hour. (From horizon to horizon is about 180 degrees.) Why do these objects appear to move at a rate of 15 degrees per hour?
_______________________________________________________
We call this motion the_________________________________
3. Apparent Solar Day: _________________________________
_________________________________________ 5
Because Earth rotates 15 degrees per hour
Apparent daily motion
How long it takes the Sun to move through our sky.
B. Terrestrial Observations1. There are two main motions of Earth:a. Revolution: ___________________________________________ ____________________________________________
Evidence: Different constellations appear in our night sky at different times of the year.
The motion of one object around another object. The planets revolve around the Sun. Moons and satellites revolve around planets.
b. Rotation: __________________________________________ ____________________
Evidence:
(1) Foucault’s Pendulum:
_____________________________
_____________________________
_____________________________
_____________________________
_______________________ ______
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A mass suspended from a wire at a single point. When set in motion, its apparent change in position is the result of the rotation of the Earth.
The spinning of an object on its axis. Earth rotates once every 24hrs.
(2) Coriolis Effect:
______________________________
______________________________
______________________________
______________________________
______________________________
The deflection of a an object that is moving above the Earth’s surface. In the Northern Hemisphere, the Coriolis effect causes moving objects to be deflected to their right, while in the Southern Hemisphere, the deflection is to the object's left.
2. Apparent Motion of the Sun: It changes with the seasons and latitude due to: ________________________ Earth does not lie directly straight up and down, it is tilted _____________
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Earth’s Tilt23 ½ degrees
Summer: __________________
__________________________
__________________________
___________ but the sun is NEVER directly overhead for us! Because the path of the sun is longest in the summer, days are longest.
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The Sun rises N of
due East and sets N of due
West. The noon Sun is highest
in the sky
Summer Solstice: _____________________________
___________________________________________
Winter: _____________________________________
___________________________________________
Winter Solstice: ______________________________
___________________________________________
Occurs approx. on June
21st
The Sun rises S of due East and sets S of
due West. The noon Sun is lowest in the sky
Occurs approx. on
December 22nd.
Spring and Fall:
______________
______________
______________
______________Vernal Equinox:
Autumnal Equinox:______________At the _______________, day and night are 12 hours long everywhere on Earth.Latitude: The closer you are to the poles, the lower the noon time sun and the greater the difference between the winter and summer length of daylight. At the equator, day and night are 12 hours long all year.
Important Note: We do not have summer in June because we are closer to the sun. We are actually closest to the sun in December, the beginning of winter. 11
The Sun rises due East and
sets due West. The noon Sun
is at approx. 48 degrees.
Approx. March 21st
Approx. September 22nd
Equinoxes
Tropics of Cancer and Capricorn: 23.5o north and south latitude. Mark the furthest north and south travel of the direct rays of the sun. Sun is directly over the Tropic of Cancer on June 21st and the Tropic of Capricorn on December 21st.
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Sun’s apparent path for four different observers on June 21st. Notice how the path and position of the noontime sun change for each location.
Because the sun is higher in the sky in the summer, the rays of the sun shine down at a more direct angle.
The length of shadows cast by a stick are also affected by the height of the sun. In the summer, the sun is high in the sky, so the shadows it casts are ______. Shadows cast in spring and fall are __________. In the winter, the sun is very low in the sky, so the shadow it casts is very ____.
long
longershort
C. Geometry of OrbitsI. Terms
A. Revolution: __________________________
B. Orbit:_______________________________1. Example: __________________________
2. Ellipse: _____________________________________________________________________
3. Focus (foci): _______________________
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The motion of one object around another object.
Path of movement of a satellite around its primary body.
The moon around the Earth.
Shape of planet’s orbits around the Sun (flattened or squashed circle).
4. Eccentricity: ___________________________
_________________________________________
a. Formula:
____________
____________
____________
____________
____________
5. Period: _________________________________
__________________________________________
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Ratio of focal length to length of major axis of an ellipse. (How flat an ellipse is)
E=d/L
II. Force and Energy
A. Gravity: __________________________________________________________________
B. Inertia: ___________________________________________________________________
C. Energy and Orbits1. At perihelion: ____________________
________________________________________________________________________________
2. At aphelion: _____________________________________________________________________________________________________ 15
The force that keeps all satellites moving inward in their curved orbits.
The tendency of an object in motion to continue in motion in a straight path.
Earth is furthest from the Sun; pull of gravity is weaker
Earth is closest to the Sun; pull of gravity is greatest
III. Orbits and Johannes KeplerA. Orbital Velocity: _____________________
B. Earth’s Orbit1. perihelion: ________________________
_________________________________________
2. aphelion: __________________________________________________________________
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Speed of orbiting object
Earth is moving the fastest
Earth is moving the slowest
C. Kepler’s Laws of Planetary Motion-Johannes Kepler, a German astronomer during the late 1500’s to early 1600’s, developed three laws of motion of objects in the sky to help better explain and predict their motions. Before Kepler, most astronomers agreed that planetary orbits were circular.1. Elliptical Orbits: ______________________
_________________________________________
2. Equal Areas: __________________________________________________________________
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The orbits of the planets are ellipses, with the Sun at one focus of the ellipse.
The line joining the planet to the Sun sweeps out equal areas in equal times as the planet travels around the ellipse.
_________
________
Orbit
Note that as the orbiting body gets closer to the object it is orbiting, the pull of gravity becomes stronger. Therefore, its forward speed must also be greater to compensate.18
Inertia
Gravity
3. Harmonic Motion:
a. Astronomical Unit: _____________________________________________________________
the period for a planet to orbit the Sun increases rapidly with the radius of its orbit
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The distance between the Earth and the Sun; 93 million miles.
D. Satellite MotionsI. The Moon: ____________________________
A. Orbit ______________________________________________________________________
1. Sidereal month: _____________________________________________________________________________________________________
2. Synodic (lunar) month: _______________________________________________________________________________________________
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Earth’s natural satelliteThe moon revolves in its orbit at the same rate that it rotates
The moon’s phases take about 29 ½ days to go through one cylce.
The moon takes 27 days to complete one revolution around Earth.
One synodic month later (29 ½ days)
(27 1/3 days)
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B. Phases: ____________________________________________________________________________________________________________________
C. Phases change from: ____________
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The apparent change in the shape of the moon caused by the changing positions of Earth, the Sun, and the Moon.
Waxing to Waning
New Moon New Crescent First Quarter
New Gibbous Full Moon Old Gibbous
Third Quarter Old Crescent
D. Because of the moon orbiting Earth, each day the moon rises over the eastern horizon ______________ ___________.
E. As a result, if you look at the moon two consecutive nights, the moon is farther ________ the second night and each night thereafter.
Day 1
in a different spot
East
C. Tides: _____________________________________________________________________________________________________________________
1. High and Low: __________________________________________________________________
2. Normal: ________________________________________________________________________
NOTE: Even though the sun is much larger, the moon is much closer so the primary force pulling on the tides is the moon.
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The twice-daily rise and fall of the oceans due to the gravitational attraction of the moon and the Sun.
2 highs and 2 lows per day, every 6 hours
Normal tidal change is less than 3 feet
3. Spring:___________________________________________________________________________
4. Neap: ____________________________________________________________________________
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Smallest change between high and low tides, moon is in the quarter phases.
Highest high tides and lowest low tides, moon phase is near full and new.
D. Eclipses: __________________________________________________________________________
1. Shadow Geometry
a. umbra: ____________________________
b. penumbra: ___________________________________________________________________
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The partial or complete obscuring (hiding) of one celestial body by another.
Inner, darker part
Outer, lighter part
2. Solar Eclipse: __________________________________________________________________
a. total: ______________________________
b. partial: ____________________________
c. annular: __________________________________________________________________
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when sun "gets dark" because the moon blocks sunlight from reaching the Earth.Solar Eclipses happen during a New Moon.
When the entire Sun is blocked out by the moon
When some of the Sun is blocked out
When the moon is further away from the Earth and you see an orange ring around the moon.
3. Lunar: ___________________________________________________________________________
a. total: __________________________________________________________________________
b. partial: ________________________________________________________________________
NOTE: Lunar eclipse does not occur during every full moon because the plane of the moon’s orbit is slightly off from Earth’s. 27
When the full moon moves into Earth’s shadow.
When the moon is closer to Earth and the Earth’s shadow completely covers it.
When the moon is further from Earth and the Earth’s shadow partially covers it.
E. The Solar SystemI. Solar System: __________________________
A. Models
1. Geocentric: __________________________________________________________________
epicycle: ____________________________________________________________________
Retrograde Motion: ___________________
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A star and it’s surrounding planets.
Model of the solar system with the Earth at the center.
The planets revolve around the Sun in circular orbits called epicycles.
Geocentric Model of the Solar System
Problem:_________________________________________________________________
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Did not explain the Focault Pendulum and the Coriolis Effect
2. First Heliocentric: ________________________________________________________________
Problem: ___________________________________________________________________________
3. Revised Heliocentric: _______________________________________________________________________________________________________ 30
Had circular orbits.
Did not explain the changing size of the Sun.
Planets move in ellipses.
B. Objects1. Sun: __________________________________
____________________________________________
a. sunspots: ___________________________
___________________________________________
b. flares/prominences: ___________________
____________________________________________
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A star that is the basis of the solar system and that sustains life on Earth, being the source of heat and light.
Dark, irregular spots that are cooler than the surrounding areas on the Sun.
a brief powerful eruption of particles and intense electromagnetic radiation from the sun's surface
10,000-27 mil. Degrees F
2. Planets: _______________________________
a. Terrestrial: ______________________________________________________________________
b. Jovian: _________________________________________________________________________
3. Asteroids: __________________________________________________________________________
A celestial body moving in an elliptical orbit around a star.
Small, inner planets made up of mostly solid rock; high density
Large, outer planets made up of mostly gases; low density.
A small rocky body orbiting the sun. Large numbers of these are found between the orbits of Mars and Jupiter
B. Objects (cont.)4. Meteors: ____________________________
___________________________________________________________________________________________________________________________
5. Comets:___________________________________________________________________________________________________________________________
Sun
Earth
Comet
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A meteoroid is a sand- to boulder-sized particle of debris in the Solar System. The visible path of a meteoroid that enters Earth's atmosphere is called a meteor, or a shooting star. If a meteoroid reaches the ground then it is called a meteorite.
They are a mixture of ices (both water and frozen gases) and dust,“dirty snowballs”
F. The UniverseI. Parts of the Universe
A. Stars: ________________________________________________________________________
1. Energy: ___________________________________________________________________
2. Composition: ______________________________________________________________
a. spectrum: ________________________________________________________________
b. spectroscope: ______________________________________________________________
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Objects in space that emit their own light.
Stars create their energy through the process of nuclear fusion.
stars are big exploding balls of gas, mostly hydrogen and helium.
Pattern of lines that show the chemical makeup of a star.
breaks down the light emitted or absorbed by chemical elements into specific lines of color.
Nebula: ______________________________________
_____________________________________________
Star Life Cycle: Stars are like humans. They are born, live and then die.:
Cloud of gas and dust where new stars are born.
Protostar: _____________
_____________________
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Mature star:___________
____________
Red Giant:__________
___________________
_____________
new, just forming star; baby star
a star with a mass like our Sun that is in the last phase of its life
pre-teen Stage
White Dwarf: ______
_________________
_________________
_________________
Supernova: ______
________________
________________
________________
________________ 36
The explosive death of a massive star whose energy output causes its expanding gases to glow brightly
an old star that has used up all of its hydrogen. Very dense.
The life cycle of stars depends on their mass.
Small and medium stars become black dwarves once they die.
Larger stars become novae and die as: ____________
The most massive stars become supernovae and die as: ______________
Neutron Star: ______________________________
_________________________________________Black Hole: _____________________________
_______________________________________
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Neutron Stars
Black Holes
Star with density so great that a teaspoon of material weighs several thousand tons.
Body of infinite density and gravity so great that not even light can escape.
3. Classifying: _________________________________________________________________________________________________________________
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B. Galaxies: _________________________________________________________________________
1. Composition: ___________________________________________________________________
2. Size: ________________________________
3. The Milky Way: _______________________________________________________________
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Large systems of stars, gas, and dust.
Millions of stars revolving around the center of the galaxy
Light years wide
Our Galaxy, a spiral galaxy( 120,000 Light years wide)
These are galaxy clusters and separate galaxies taken by long-range telescope. The area of the sky covered is less than the diameter of the moon.
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C. Clusters: ______________________________________________________________________
II. Distance in the UniverseA. The speed of light: ___________________
_________________________________________
B. The Light Year: ______________________________________________________________
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Contain millions of galaxies
186,000 miles/sec.
How long it takes light to travel in one year
III. The Expanding UniverseA. The Big Bang Theory: ________________
__________________________________________________________________________________
B. Doppler ShiftShows a change in a star's spectrum; evidence that the
universe is expanding
1. red shift: ___objects are moving away from us_______________________
__________________________________________2. blue shift: __objects are moving towards us_______________________
__________________________________________
Since the spectrum for all galaxies show a _______ from Earth, we assume the universe is __________
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