Sun-Earth-Moon System Ch 20. Section 1: Earth’s Motion I)Earth and Sun A) Earth is ALWAYS moving (even though we don’t feel it) B) Around the Sun 1) Nearest.

Sun-Earth-Moon System

Ch 20

Section 1: Earth’s MotionI) Earth and Sun

A) Earth is ALWAYS moving (even though we don’t feel it)B) Around the Sun

1) Nearest star – 150 million km away from Earth

2) 100 times bigger than Earth 3) Mass is 300,000 times greater

4) Inside Sun:*Nuclear Fusion – nuclei of atoms

combine releasing HUGE amounts of energy! * SMALL part (of Sun’s energy) reaches EARTH!

Sect. 1 Cont.C) Earth’s movement around Sun

1) Revolution ~ motion of one object around another object.

2) Orbit ~ the path an object follows as it moves around another object.

*Earth’s path is not a perfect circle (close but not quite) – ellipse.3) 365.24 days … (Know why we have leap year?? Make up for that .24!!) 4) Earth revolves around Sun because of … SUN’s GRAVITY pulls on Earth. 5) Demo … ball on string

Sect. 1 Cont.

D) Earth ROTATES on its axis.1) Causes ~ day (part of Earth facing Sun) and night (part of Earth away from Sun)!

2) Rotation ~ is spinning motion. 3) Rotation axis ~ line on which

an object rotates.4) Rotates COUNTERCLOCK wise.

Sect. 1 Cont.

5) Earth rotates from WEST to EAST ~ causing …* Sun / stars / moon to appear to move from East to West.

6) Earth’s axis is tilted ~ sometimes tilted toward Sun … sometimes away.

Sect. 1 Cont.

II)Shape of EarthA) Sphere – causes different parts to receive different amounts of Sun’s energy.

* Equator - more direct Sunlight /warmer

(receives more energy)* Northern / Southern Hemisphere

- more spread out / colder (receives less energy)

Sect. 1 Cont.B) Earth is Tilted 23.5 degrees …

* INFLUENCES our SEASONS!

III) Seasons A) Cause of Seasons ~ combination of

1) TILT !!! 2) Revolving around SUN 3) REMEMBER ~

*CLOSEST to Sun in WINTER *FARTHEST to Sun in SUMMER *TILT is what makes us warmer or

cooler!

http://www.youtube.com/watch?v=DuiQvPLWziQ

Sect. 1 Cont.

B) Solstice (Def: day when Earth’s rotation axis is the most toward or away from the sun) 1) December Solstice (Winter for us)

*Northern Hemisphere – shortest day and longest night. (Tilted AWAY from Sun)

*Southern Hemisphere – longest day and shortest night. (Tilted TOWARD Sun)

Sect. 1 Seasons Cont.

2) June Solstice (Summer for us)*Northern Hemisphere is tilted TOWARD Sun.

- Longest day and shortest night.*Southern Hemisphere is tilted AWAY from Sun. (Their winter)

- Shortest day and longest night.

Sect. 1 Seasons Cont.C) Equinox (Def ~ day when Earth’s rotation

axis is leaning along Earth’s orbit neither toward nor away from Sun.) 1) September Equinox

*Northern Hemisphere = Fall 12 hours day and night.

*Southern Hemisphere = Spring2) March Equinox

*Northern Hemisphere = Spring12 hours day and night

*Southern Hemisphere = Fall

Websites

• Teachers Domain – seasons • There is a “tutorial” on the book website too.

End Sect. 1

• Assignment …• Worksheets – yes due tomorrow!

Sect. 2 ~ The MOON

I) Moon infoA) Formation:

1) Shortly after Earth formed – Mars size planet hit Earth.

2) Sent vaporized rock into ring around Earth.

3) Eventually, formed into our Moon.

I) Moon Info cont. B) Surface: No atmosphere or liquid water or plate

tectonics to change surface.

1) Craters - bowl shaped dip from space objects crashing into the Moon.

2) Maria – dark flat areas that formed from lava hardening.

3) Highlands – light colored areas w/ craters (too high for the lava to cover so no maria there) … oldest area on moon.

4) Rays – bright streaks around craters.

I) Moon’s Info. Cont.C) Moon’s Motion

1) Revolves around Earth in 27.3 days – gravitational pull of Earth on Moon.2) Rotates counterclockwise around in 27.3 days – means …

#3) IMPORTANT … same side of Moon faces Earth at all times!!!

*Side we see = NEAR side*Side we do not see = FAR side

II) Phases of Moon• Phases – portion of Moon lit up by Sun (part

we see – some planets also have phases).A) Waxing Phases – increasing light on Moon(DRAW!!) **Right side lit up**

1) Waxing Crescent2) 1st Quarter3) Waxing Gibbous 4) Full Moon

Moon Earth Sun in a line

II) Phases Cont.

B) Waning Phases – light is decreasing ** Left side lit up **1)Waning Gibbous 2)3rd Quarter or Last 3)Waning Crescent4)New Moon

No light Earth Moon Sun in a line

Website …

Assignment ~

• Worksheets

Sect. 3 ~ Eclipses and TidesI) Eclipses: produced by shadows of Earth or

Moon.A) Parts of a shadow:

1) Umbrai) Darkest part of a shadowii) In the center or middle

2) Penumbrai) Lighter part of a shadow (light is partially

blocked.ii) On the sides … or outside of the umbra

I) Eclipses – cont.B) Solar Eclipse

1) Def: Moon’s shadow appears on Earth’s surface. 2) Position: Earth Moon Sun (New Moon Phase) 3) Total – occurs only for those in Umbra.4) Partial – occurs for those in Penumbra.5) Why don’t we have one every New Moon?

*Moon’s orbit is tilted about 5 degrees from Earth’s orbit so they rarely line up for Solar Eclipse.

Website

• http://www.teachersdomain.org/asset/ess05_vid_totaleclipse/

• How many people see a solar eclipse? • Very few – Moon’s shadow is small compared

to Earth.

I) Eclipses cont.

C) Lunar Eclipse:1) Def: Moon moves into Earth’s shadow.2) Position: Sun, Earth, Moon in a line – can ONLY occur during Full Moon. 3) Total and Partial occur.4) Again – doesn’t happen every full moon due to Moon’s orbit

Website:

• http://www.youtube.com/watch?v=IKQkM474UE0&feature=related

• How many people can see a lunar eclipse? • Anyone on Earth who can see the moon –

more than can see a solar eclipse.• How often can one occur?• About every 6 months.

II) TidesA) Def:

1) Daily rise and fall of sea level.2) Bulges of Earth’s Oceans. 3) P. 748 Figure 20 … High & Low Tide

B) Happens: twice each day.

C) Cause: 1) Moon’s gravitational pull on Earth.2) Sun’s gravitational pull has a smaller effect –

causes “special” ones …

II) Tides cont. D) where Moon & Sun’s grav. work together.

1) Spring Tides: Full & New Moon phase – E, M, S lined up.

*HIGH tides are higher than usual.*LOW tides are lower than usual.2) Neap Tides: S, E, M form a right angle

(90 deg.) *HIGH tides are lower than usual.*LOW tides are higher than usual.(P. 748 Fig. 21 bottom of page)

Finished Chapter – Whew!

• Review assignment:• P. 753 Copy and do Concept Map (8-15)• P. 754 (1-10 Multiple Choice)• P. 755 SENTENCES!! (14, 16, 17)