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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