1. Earth-Sun-Moon System

2. 1-1: Movement in Space The Night Sky Stars, Planets, and the Moon
What can we see in the night sky with our naked eye?
Stars, Planets, and the Moon
Stars - are seen as dots of light, but are really giant balls of gas
Planets – orbit around the Sun (star)
Moon – Earth’s natural satellite

3. 1-1: Movement in Space - Meteors and Comets
Meteors are flashes of light when a meteoroid (small rock) burns up in atmosphere
Comets are chunks of dust and ice that orbit a star, they form tails when close to the Sun

4. 1-1: Movement in Space Constellations
-Patterns seen in a group of stars
-People imagined they saw figures, animals, or objects
-Sky is divided up into constellations
- Some constellations are named for Greek myths

5. 1-1: Movement in Space Movement in the Sky
Movement of objects in the sky depend on the movements of Earth
Seasonal Changes
Constellations and star patterns change from season to season
Ex. Orion visible in winter, not in summer

6. 1-1: Movement in Space Movement in the Sky Planets
Appear to move against the background of stars
Appear to move through a narrow band in the sky called the zodiac

7. Models of the Solar System
1-1: Movement in Space
Models of the Solar System
Geocentric Model
Aristotle based model on observations
Earth at the center of the universe
All planets and stars circle Earth
Ptolemy added to model, planets made small circles as they moved in their orbit paths

8. 1-1: Movement in Space Models of the Solar System Heliocentric Model
Copernicus
proposed that Earth’s rotation and revolution around the Sun explained the movements of stars and planets
Brahe and Kepler
Used Brahe’s observations to determine the orbit of each planet is an ellipse, not a perfect circle
Galileo
Discovered moons around Jupiter, showed that not everything travels around Earth

9. 1-2: Earth’s Movement in Space
How Earth Moves
Rotation
Earth spins on its axis
Earth rotates from west to east
Stars, the moon, the Sun appear to move from east to west in the sky
Earth takes 24hr, or a day, to complete 1 rotation

10. 1-2: Earth’s Movement in Space
How Earth Moves
Revolution
Movement of Earth around the Sun
Earth follows a path, or orbit
Earth’s orbit is an ellipse, but very close to being a circular path
Earth takes days, or one year, to complete 1 revolution

12. 1-2: Earth’s Movement in Space
The Seasons
Sunlight hits in different amounts due to Earth’s shape
Locations near the equator get direct sunlight, locations near the poles get angled sunlight.
This why it is warmer near the equator and colder at the poles

13. 1-2: Earth’s Movement in Space
The Seasons cont’d
Seasons depend on the tilt of the Earth’s axis
Earth’s axis is tilted 23.50
Earth’s tilt creates changes in temperature due to amount of sunlight
Earth has seasons because its axis is tilted as it revolves around the Sun.

14. 1-2: Earth’s Movement in Space
The Seasons cont’d
Day Length
Part of Earth tilted toward the sun get more hours of daylight than the part of Earth tilted away from the sun
Summer = Longer daylight hours
Winter = Shorter daylight hours

15. 1-2: Earth’s Movement in Space
The Seasons cont’d
Solstices and Equinoxes
Solstices
When Northern or Southern Hemisphere is tilted toward or away from the Sun
December Solstice, June Solstice
Equinoxes
When hemisphere is tilted toward or away from the Sun

17. Solstices

18. Equinoxes

19. 1-2: Earth’s Movement in Space
Gravity and Orbits
Gravity
Force that keeps the Earth in orbit around the Sun
Newton’s Law of Universal Gravitation
Every object in the universe attracts every other object
Strength of force of gravity between 2 objects depends on –
Masses of objects
Distance between objects

20. 1-2: Earth’s Movement in Space
Gravity and Orbits
Inertia
Inertia keeps the Earth from being pulled into the Sun
The tendency of an object to resist a change in motion
Newton’s 1st Law = Inertia
An object at rest will stay at rest and an object in motion will stay in motion unless acted upon by a force

21. 1-2: Earth’s Movement in Space
Gravity and Orbits
Orbital Motion
Inertia and Force of gravity keep objects in their orbital motion
Earth’s gravity pulls the moon toward it
The Moon’s inertia keep it in its orbital path
Without Earth’s gravity, the Moon would fly off into space in a straight line

22. The Appearance of the Moon
1-3: Phases and Ellipses
The Appearance of the Moon
The Two Sides of the Moon
Near side – faces Earth
Darker areas – maria
Lighter areas – highlands
Craters
Far side – faces away from Earth

23. 1-3: Phases and Ellipses The Appearance of the Moon
Motions of the Moon
The Moon rotates and revolves
The Moon’s rotation period and revolution period are both about 1 month
The same side of the moon always faces the Earth
From space, half of the moon is always lit from the Sun
From Earth, the lit part of the moon visible from Earth changes

24. 1-3: Phases and Ellipses The Appearance of the Moon Phases of the Moon
Different shapes of the lit side of the moon visible from Earth
New moon
Waxing cresent
First quarter
Waxing gibbous
Full moon
Waning gibbous
Third quarter
Waning cresent

26. 1-3: Phases and Ellipses The Appearance of the Moon Eclipses
When an object in space comes in between the Sun and a third object it casts a shadow
Shadow has 2 parts
Umbra – darkest shadow, total eclipse
Penumbra – lighter shadow, partial eclipse
2 types of Eclipses
Solar Eclipse – moon between Earth and Sun
Lunar Eclipse – Earth between Moon and Sun

28. 1-3: Phases and Ellipses The Appearance of the Moon Tides
Rise and fall of ocean water that occur about every 12.5 hr
The Moon and the Sun
Moon’s gravity pulls on the side of Earth facing the moon
Pull causes a tidal bulge on one side of the Earth
Another tidal bulge forms on the opposite side of the Earth
As Earth rotates, the tidal bulge will move creating high and low tides

29. 1-3: Phases and Ellipses Tides cont’d The Moon and the Sun
The Sun’s gravity can influence tides as well, just not as much as the Moon
The changing positions of the Sun and Moon affect the changing levels of the tides
Spring and Neap Tides
Spring Tide – most significant difference in low and high tides
Neap Tide – least significant difference in low and high tides