9.12.12

9.12.12Before the BellEnter QUIETLY

Take a seat BEFORE THE BELL RINGS

Turn to Pg 36 in notebook and begin Warm-UpWarm-UpOpen your notebooks to Pg 36Make a list of EVERYTHING that you can think of that is dependent on the SunTHINK HARD!Classroom CultureNot good enoughThe more yall help Ms. M, the better class will beGrades are almost a DIRECT reflection of how much EFFORT you put in!Guided Notes3 topics to cover todayRotation of earthRevolution of earthRotation of Earth_What We KnowEarth rotates on its axis

It takes approx. 24 hours for the earth to rotate

Rotation of Earth_NEWThe rotation of the earth causes day & night

When the earth faces the sun, it is day

When the earth faces away from the sun, it is nightRotation ActivityMusical Chairs

Board is Sun

Ms. M will play music, when playing turn in a circle, when stop, freeze

Notice if you are in daylight or darkness

What happens to day/nighttime if turn faster?Concept Application_ From 9/11How would the length of day & night change if the earth rotated slower?How would these lengths change if the earth rotated faster?Earths Revolution_What We KnowEarth revolves around the sun once per year

It takes 365 days for the sun to rotate

As the sun rotates, it spins on its axisEarths Revolution_NEWCaused by the Sun

The Sun exerts a pull on the Earth

Without the Sun, the earth would travel in a straight line into outer spaceRevolution ActivityRotate around the classroom QUIETLY

Discuss in groups how this relates to earths revolution around the SunAnimationClasszone.com/books/earth_science/terc/content/visualizationses0408The Seasons

Earths axis of rotation is inclined vs. the normal to its orbital plane by 23.5, which causes the seasons.

The Seasons (2)

They are not related to Earths distance from the sun. In fact, Earth is slightly closer to the sun in (northern-hemisphere) winter than in summer.Light from the sunSteep incidence SummerShallow incidence WinterThe Seasons are only caused by a varying angle of incidence of the suns rays.

Seasons

(SLIDESHOW MODE ONLY)The Seasons (3)Northern summer = southern winter

Northern winter = southern summer

The Seasons (4)Earths distance from the sun has only a very minor influence on seasonal temperature variations.SunEarth in JulyEarth in JanuaryEarths orbit (eccentricity greatly exaggerated)

Astronomical Influences on Earths Climate (2)

Last glaciationEnd of last glaciationPolar regions receiving less than average energy from the sunPolar regions receiving more than average energy from the sun

COPY AND ANSWER

How would the seasons be different if Earth were inclined 90 instead of 23.5? 0 instead of 23.5?

What would happen to life on earth if the Sun went away?Discussion Questions

News BroadcastThe Sun has just burned out

Create a broadcast that announces this to your fellow POB peers that describes what will happen to our life on Earth

Write the broadcast on NOTEBOOK PAPER!

Will have a few presentJournal EntryStudents will write a detailed short answer response that explains what would happen to life on earth if the seasons changedSociallyEconomy: Grocery stores, FarmersHousingPlant lifeAnimal life

The Motion of the PlanetsThe planets are orbiting the sun almost exactly in the plane of the Ecliptic.JupiterMarsEarthVenusMercurySaturnThe Moon is orbiting Earth in almost the same plane (Ecliptic).

Shadow and Seasons

(SLIDESHOW MODE ONLY)The Motion of the Planets (2)

All outer planets (Mars, Jupiter, Saturn, Uranus, Neptune and Pluto) generally appear to move eastward along the Ecliptic. The inner planets Mercury and Venus can never be seen at large angular distance from the sun and appear only as morning or evening stars.

The Motion of the Planets (3)Mercury appears at most ~28 from the sun.It can occasionally be seen shortly after sunset in the west or before sunrise in the east.Venus appears at most ~46 from the sun. It can occasionally be seen for at most a few hours after sunset in the west or before sunrise in the east.

Astronomical Influences on Earths ClimateFactors affecting Earths climate: Eccentricity of Earths orbit around the Sun (varies over period of ~ 100,000 years) Precession (Period of ~ 26,000 years) Inclination of Earths axis versus orbital plane

Milankovitch Hypothesis: Changes in all three of these aspects are responsible for long-term global climate changes (ice ages).

Astronomical Influences on Earths Climate (2)

Last glaciationEnd of last glaciationPolar regions receiving less than average energy from the sunPolar regions receiving more than average energy from the sun

constellationasterismmagnitude scaleapparent visual magnitude (mv)celestial spherehorizonzenithnadirnorth celestial polesouth celestial polecelestial equatornorth pointsouth pointeast pointwest pointangular distanceminute of arcsecond of arcangular diametercircumpolar constellationscientific modelprecessionrotationrevolutioneclipticvernal equinoxsummer solsticeautumnal equinoxwinter solsticeperihelionaphelionevening starmorning starzodiachoroscopeMilankovitch hypothesisNew Terms

1. Have you thought of the sky as a ceiling? as a dome overhead? as a sphere around Earth? as a limitless void?

2. How would the seasons be different if Earth were inclined 90 instead of 23.5? 0 instead of 23.5? Discussion Questions

Quiz Questions1. The remaining 48 ancient constellations that we still recognize today are located

a. along the ecliptic.b. along the celestial equator.c. near the south celestial pole.d. at mid and northern celestial latitudes.e. uniformly around the celestial sphere.Quiz Questions2. Which statement below most accurately describes modern constellations?

a. They are 88 well defined regions on the celestial sphere.b. They are 88 connect-the-dot mythological sky figures.c. They are 13 connect-the-dot mythological sky figures along the ecliptic.d. They are 13 well defined sky regions along the ecliptic.e. They are 88 groups of stars with members of each constellation physically close together in space.Quiz Questions3. What is the most likely Greek letter name of the second brightest star in the constellation Lyra?

a. alpha Lyrae.b. beta Lyrae.c. gamma Lyrae.d. delta Lyrae.e. epsilon Lyrae.Quiz Questions4. The apparent visual magnitudes of four stars are listed below. Of these four stars which one appears dimmest in the sky?

a. - 0.5b. +2.8c. -1.2d. +0.7e. It cannot be determined from the given information.Quiz Questions5. Which pair of apparent visual magnitudes listed below indicates that we receive about 16 times as much visible light from star W than from star X?

a. mv star W = 16, and mv star X = 1 b. mv star W = 1, and mv star X = 16 c. mv star W = 1, and mv star X = 6d. mv star W = 5, and mv star X = 2 e. mv star W = 2, and mv star X = 5 Quiz Questions6. The apparent visual magnitude of star A is 2 and the apparent visual magnitude of star B is 1. Based on this information which statement below must be true?

a. Star A emits more light than star B.b. Star B emits more light than star A.c. Star A is closer than star B.d. Star B is closer than star A.e. Light output and distance cannot be determined from a star's apparent visual magnitude alone.Quiz Questions7. If the apparent visual magnitude of the Sun is -26.5 and that of the full moon is -12.5, what is the light intensity ratio of sunlight to moonlight received at Earth on the day of the full moon?

a. 40b. 100c. 4000d. 10,000e. 400,000Quiz Questions8. When you observe a star on the celestial equator for a period of a few hours, you notice that it

a. moves from north to south relative to the horizon.b. moves from south to north relative to the horizon.c. moves from east to west relative to the horizon.d. moves from west to east relative to the horizon.e. does not move relative to the horizon.Quiz Questions9. What is responsible for the motion described in the previous question?

a. All celestial objects orbit around Earth. b. Earth's rotation on its axis.c. Earth's revolution around the Sun. d. The Sun's motion around the center of the galaxy.e. The motion of Earth's tectonic plates.Quiz Questions10. At what location on Earth is an observer who has the south celestial pole directly overhead?

a. At Earth's equator (0 degrees latitude).b. At Earth's North Pole (90 degrees North latitude).c. At Earth's South Pole (90 degrees South latitude).d. At 45 degrees North latitude.e. At 45 degrees South latitude.Quiz Questions11. At what location on Earth is an observer who has the celestial equator passing through a point directly overhead?

a. At Earth's equator (0 degrees latitude).b. At Earth's North Pole (90 degrees North latitude).c. At Earth's South Pole (90 degrees South latitude).d. At 45 degrees North latitude.e. At 45 degrees South latitude.Quiz Questions12. If the tilt of Earth's axis were to change from 23.5 degrees to 0 degrees what celestial circles would coincide for all observers?

a. The celestial equator and the horizon.b. The horizon and the ecliptic.c. The celestial equator and the ecliptic.d. The horizon and the celestial equator.e. The horizon, the ecliptic, and the celestial equator.Quiz Questions13. Why does the rotational axis of Earth precess?

a. The Sun and Moon pull on Earth's equatorial bulge.b. The Earth's spin rate is decreasing.c. The Earth's spin rate is increasing.d. The shrinking of the Antarctic ice sheet, brought on by global warming.e. The Sun's magnetic field interacts with Earth's magnetic field.Quiz Questions14. The precession of Earth's rotational axis causes the location of the

a. north celestial pole and south celestial pole to change.b. vernal equinox and autumnal equinox to change.c. summer solstice and winter solstice to change.d. Both a and b above.e. All of the above.Quiz Questions15. If you could see the Sun and stars during the daytime for several weeks you would notice that the Sun

a. never moves relative to the stars.b. moves slowly westward relative to the stars.c. moves slowly eastward relative to the stars.d. sometimes moves westward and at other times eastward relative to the stars.e. rises in the west and sets in the east.Quiz Questions16. Why does the Sun move relative to the stars as described in the previous question?

a. It is due to Earth rotating on its axis.b. It is due to Earth revolving around the Sun.c. It is due to the Sun rotating on its axis.d. It is due to the Sun revolving around the center of our galaxy.e. The Sun does not move relative to the stars.Quiz Questions17. Why is amount of solar heating less on a clear day in January at northern latitudes than on a clear day in July?

a. The Sun is above the horizon for less than 12 hours in January in the north.b. Earth is farther from the Sun in January and closer in July.c. At low Sun angles, the received sunlight is spread over a larger surface area.d. Both a and b above.e. Both a and c above.Quiz Questions18. When it is autumn in Asia, what season is it in Antarctica?

a. Autumn.b. Winter.c. Spring.d. Summer.e. Antarctica does not have seasons.Quiz Questions19. The five naked-eye planets and three telescopic planets that wander among the stars in the sky are always near the

a. horizon.b. celestial equator.c. ecliptic.d. Moon.e. Sun.Quiz Questions20. The Milankovitch hypothesis proposes that the ice ages on Earth are due to long-term changes in the amount of seasonal solar heating brought about by

a. changes in the shape of Earth's orbit.b. precession of Earth's rotational axis.c. changes in the tilt angle of Earth's rotational axis.d. Both a and c above.e. All of the above.Answers1.d2.a3.b4.b5.e6.e7.e8.c9.b10.c11.a12.c13.a14.e15.c16.b17.e18.c19.c20.eNote that the following lectures include animations and PowerPoint effects such as fly ins and transitions that require you to be in PowerPoint's Slide Show mode (presentation mode).The Cycles of the MoonChapter 3

In the preceding chapter, we saw how the sun dominates our sky and determines the seasons. The moon is not as bright as the sun, but the moon passes through dramatic phases and occasionally participates in eclipses. The sun dominates the daytime sky, but the moon rules the night. As we try to understand the appearance and motions of the moon in the sky, we discover that what we see is a product of light and shadow. To understand the appearance of the universe, we must understand light. Later chapters will show that much of astronomy hinges on the behavior of light. In the next chapter, we will see how Renaissance astronomers found a new way to describe the appearance of the sky and the motions of the sun, moon, and planets. Guidepost

I. The Changeable MoonA. The Motion of the MoonB. The Cycle of Phases

II. The TidesA. The Cause of the TidesB. Tidal Effects

III. Lunar EclipsesA. Earth's ShadowB. Total Lunar EclipsesC. Partial and Penumbral Lunar EclipsesOutline

IV. Solar EclipsesA. The Angular Diameter of the Sun and MoonB. The Moon's ShadowC. Total Solar Eclipses

V. Predicting EclipsesA. Conditions for an EclipseB. The View From SpaceC. The Saros CycleOutline (continued)

The Phases of the Moon (1)

The Moon orbits Earth in a sidereal period of 27.32 days.27.32 daysEarthMoonFixed direction in space

The Phases of the Moon (2)

The Moons synodic period (to reach the same position relative to the sun) is 29.53 days (~ 1 month).Fixed direction in spaceEarthMoonEarth orbits around Sun => Direction toward Sun changes!29.53 days

The Phases of the Moon (3)From Earth, we see different portions of the Moons surface lit by the sun, causing the phases of the Moon.

The Phases of the Moon (4)

New Moon First Quarter Full MoonEvening Sky

The Phases of the Moon (5)

Full Moon Third Quarter New MoonMorning Sky

The TidesCaused by the difference of the Moons gravitational attraction on the water on Earth 2 tidal maximaExcess gravity pulls water towards the moon on the near sideForces are balanced at the center of the Earth 12-hour cycleExcess centrifugal force pushes water away from the moon on the far side

Spring and Neap Tides

The Sun is also producing tidal effects, about half as strong as the Moon. Near Full and New Moon, those two effects add up to cause spring tides. Near first and third quarter, the two effects work at a right angle, causing neap tides.Spring tidesNeap tides

The Tidally-Locked Orbit of the Moon

The Earth also exerts tidal forces on the moons rocky interior.

It is rotating with the same period around its axis as it is orbiting Earth (tidally locked).

We always see the same side of the moon facing Earth.

Acceleration of the Moons Orbital Motion

Earths tidal bulges are slightly tilted in the direction of Earths rotation.Gravitational force pulls the moon slightly forward along its orbit.

Lunar Eclipses

Earths shadow consists of a zone of partial shadow, the Penumbra, and a zone of full shadow, the Umbra.If the moon passes through Earths full shadow (Umbra), we see a lunar eclipse.If the entire surface of the moon enters the Umbra, the lunar eclipse is total.

A Total Lunar Eclipse (1)

A Total Lunar Eclipse (2)

A total lunar eclipse can last up to 1 hour and 40 min.During a total eclipse, the moon has a faint, red glow, reflecting sun light scattered in Earths atmosphere.

Lunar Phases

(SLIDESHOW MODE ONLY)Lunar Eclipses: 2002-2012Typically, 1 or 2 lunar eclipses per year.

Small Angle Formula

(SLIDESHOW MODE ONLY)Solar Eclipses

The sun appears approx. as large in the sky (same angular diameter ~ 0.50) as the moon. When the moon passes in front of the sun, the moon can cover the sun completely, causing a total solar eclipse.

Solar Eclipses: 2002-2012Approximately 1 total solar eclipse per year

Total Solar Eclipse

ProminencesChromosphere and Corona

Solar Atmosphere Revealed

Diamond Ring Effect

Earth and Moons Orbits Are Slightly EllipticalSunEarthMoon(Eccentricities greatly exaggerated!)Perihelion = position closest to the sunAphelion = position furthest away from the sunPerigee = position closest to EarthApogee = position furthest away from Earth

Annular Solar Eclipses

The angular sizes of the moon and the sun vary, depending on their distance from Earth.When Earth is near perihelion, and the moon is near apogee, we see an annular solar eclipse.PerigeeApogeePerihelionAphelion

Annular Solar Eclipses (2)

Almost total, annular eclipse of May 30, 1984

Conditions for Eclipses (1)

A solar eclipse can only occur if the moon passes a node near new moon.The moons orbit is inclined against the ecliptic by ~ 50.A lunar eclipse can only occur if the moon passes a node near full moon.

Conditions for Eclipses (2)

Saros cycle: 18 years, 11 days, 8 hoursEclipses occur in a cyclic pattern.

The Saros Cycle

sidereal periodsynodic periodspring tidesneap tidesumbrapenumbratotal eclipse (lunar or solar)partial eclipse (lunar or solar)penumbral eclipsesmall-angle formulapath of totalityphotospherecoronachromosphereprominencediamond ring effectannular eclipseperigeeapogeenodeeclipse seasonline of nodeseclipse yearsaros cycleNew Terms

1. If the moon were closer to Earth such that it had an orbital period of 24 hours, what would the tides be like?

2. How would eclipses be different if the moons orbit were not tipped with respect to the plane of Earths orbit?

3. Are there other planets in our solar system from whose surface we could see a lunar eclipse? a total solar eclipse?

4. Can you detect the Saros cycle in Figure 3-18? Discussion Questions

Quiz Questions1. Which statement below best describes the motion of the Moon relative to the stars?

a. The Moon moves eastward relative to the stars about 1 degree per day.b. The Moon moves westward relative to the stars about 1 degree per day.c. The Moon moves eastward relative to the stars about 13 degrees per day.d. The Moon moves westward relative to the stars about 13 degrees per day.e. The Moon does not move relative to the stars.Quiz Questions2. How does the Moon's motion relative to the stars compare to the Sun's motion relative to the stars?

a. The Moon moves slower than the Sun and in the same direction.b. The Moon moves faster than the Sun and in the same direction.c. The Moon moves slower than the Sun and in the opposite direction.d. The Moon moves faster than the Sun and in the opposite direction.e. The Moon does not move relative to the stars.Quiz Questions3. How does one cycle of the Moon's motion relative to the stars compare to one cycle of the Moon's motion relative to the Sun?

a. The two cycles take the same amount of time.b. The cycle relative to the stars is shorter than the cycle relative to the Sun.c. The cycle relative to the stars is longer than the cycle relative to the Sun.d. The two cycles vary in length, such that at times the star cycle is shorter and at other times the Sun cycle is shorter.e. The Moon does not move relative to the Sun.Quiz Questions4. The time for one cycle of lunar phases is

a. about one day.b. about 24.8 hours.c. about one year.d. the same as the time for one cycle of the Moon relative to the stars.e. the same as the time for one cycle of the Moon relative to the Sun.Quiz Questions5. In one cycle of lunar phases each crescent and gibbous phase has a duration of about one

a. hour.b. day.c. week.d. month.e. year.Quiz Questions6. If the moon reaches Full phase on May 6, it is at _____ phase on May 17.

a. Newb. Waxing Crescentc. Waxing Gibbousd. Waning Gibbouse. Waning CrescentQuiz Questions7. During Third Quarter phase, the Moon will rise at about

a. Sunriseb. Noonc. Sunsetd. Midnighte. There is no way to predict the time that a particular phase rises.Quiz Questions8. Which statement below is the best simple description of the tidal force?

a. It is an attractive gravitational force due to the presence of very high-mass celestial bodies.b. It is a centripetal (center attracting) force due to rapid rotation.c. It is a centrifugal (center fleeing) force due to rapid rotation.d. It is a differential gravitational force that acts on the different parts of a body.e. It is a centrifugal force due to orbital motion.Quiz Questions9. The ocean tides on Earth are primarily due to the influence of what celestial body?

a. The Sun.b. The Moon.c. Venus.d. Mars.e. Jupiter.Quiz Questions10. How many tidal bulges on planet Earth are due to the Moon's gravitational influence?

a. Zero.b. One.c. Two.d. Three.e. Four.Quiz Questions11. The most extreme tides (Spring Tides) on planet Earth occur during which phase of the Moon?

a. Newb. First Quarterc. Fulld. Third Quartere. Both a and c above.f. Both b and d above.Quiz Questions12. What changes occur in the Earth-Moon system due to tidal forces?

a. Earth's rate of rotation is slowing.b. The same side of the Moon now always faces Earth.c. The Earth-Moon distance is increasing.d. Both a and c above.e. All of the above.Quiz Questions13. The least extreme tides (Neap Tides) on planet Earth occur during which moon phase?

a. Newb. First Quarterc. Fulld. Third Quartere. Choices a and c above.f. Choices b and d above.Quiz Questions14. Which of the following is true about the umbra of the Moon's shadow?

a. It is very dark, or a total shadow.b. It is semi-dark, or a partial shadow.c. Its "cone" points away from the Sun.d. Its "cone" points toward the Sun.e. Choices a and c above.f. Choices b and d above.Quiz Questions15. During a total lunar eclipse the Moon is

a. completely dark.b. a reddish color.c. in Earth's umbra.d. in Earth's penumbra.e. Both b and c above.f. Both a and c above.Quiz Questions16. Which type of eclipse may be visible to all the people on one side of Earth?

a. An annular eclipse.b. A total solar eclipse.c. A total lunar eclipse.d. None of the above.e. All of the above.