1. Sun-Earth-Moon connections

2. Review Question
People once believed that all planets and stars orbited around ____.
Mercury
Earth
Venus
Mars

3. The Rotating Earth is a sphere, a round 3-dimensional shape
bulges slightly at equator and flattens slightly at poles
Radius: same from all points on the surface
Axis/Tilt: imaginary vertical line through the north and south poles it spins on

4. What is Earth’s rotation?
Rotation: spinning of earth on its axis, causes days and nights
One complete rotation in 24 hours
completes 365 rotations in a one year journey around the Sun
rotates from west to east

5. What is a Foucault pendulum?
Weight on a string suspended from a support and swings freely.
Swings in a constant direct but as earth turns it appears the pendulum shifts orientation.

6. Earths Rotation
Compass always points north is evidence of earth’s magnetic field
Earth’s magnetic axis and rotational axis are not at the same points
Thus, your compass would take you to magnetic north not the north pole
Magnetic north changes and moves around rotational north

7. What is the Coriollis Effect?
rotation of Earth causes ocean currents and wind belts to curve to the left or right

8. What is Earths Revolution?
Revolution- the motion of a body that travels around another body in space; one complete trip along an orbit
a satellite of Sun
Earth’s orbit around the Sun is an Ellipse, an elongated closed curve
is traveling around the sun at an average speed of 29.8 km/s.
Aphelion: planet is farthest from the sun
Perihelion: planet is closest to the sun.

9. What causes the changes in seasons ?
is tilted 23.5°
causes our change in seasons
makes daylight longer in summer and shorter in winter
hemisphere tilted toward the Sun has longer hours of daylight and makes summer warmer

10. Reasons for Seasons

11. What is an Equinox?
Equinox: occurs when the Sun is directly over the equator; causing spring and fall
THINK EQUAL: Hours of daylight and nighttime
Spring equinox is Mar 21 and Fall equinox Sep 22

12. What is a Solstice?
hemisphere tilted toward the Sun receives and absorbs more solar radiation; causing summer
Solstice: is the day when the Sun rays are at its greatest/least distance from the equator
June 21:longest daylight
Dec 21: shortest daylight

13. Reasons for Seasons

14. Incoming solar radiation

16. The Moon: Properties, history, phases, eclipses, and tides

17. What is the moon? A natural satellite
Satellite: a natural or artificial body that revolves around planet.
One of more than 96 moons in our Solar System
The only moon of the planet Earth

18. What is the moons Distance, Size, and Gravity?
About 384,000 km (240,000 miles) from Earth
3,468 km (2,155 miles) in diameter (about ¼ the size of Earth)
1/6 of Earths gravity

19. What is the moons internal structure?
3 major divisions of the Lunar interior
Crust - average thickness of about 70 kilometers
Mantle
Core - radius is between 300 and 425 kilometers
Determined via seismic data from “moonquakes”

20. What are some lunar features?
No atmosphere
No liquid water
Extreme temperatures
Daytime = 130C (265°F)
Nighttime = -190C (-310 F)

21. Lunar Features – Highlands (Terrae)
Mountains up to 7500 m (25,000 ft) tall
Rilles (trenchlike valleys)
Anorthosite: light patches seen on the moon’s surface

22. Lunar Features - Craters
a bowl-shaped depression that forms on the surface of an object when a falling body strikes the object’s surface or when an explosion occurs]
Up to 2500 km (1,553 miles) across
Most formed by meteorite impact on the Moon
Some formed by volcanic action inside the Moon

23. Crater Formation

24. Crater formation

25. Lunar Features - Maria
Originally thought to be “seas” by early astronomers
Darkest parts of lunar landscape
Filled by lava after crash of huge meteorites on lunar surface 3-4 billion years ago
Mostly basalt rock

26. Prominent Maria

27. Craters vs Maria

28. What is the moons rotation and revolution?
Revolution – Moon orbits the Earth every 29.5days
The moon rises in the east and sets in the west
The moon rises and sets 50 minutes later each day
Rotation – Moon turns on its axis every 29 days
Same side of Moon always faces usarth

29. What shape is the moons orbit around the sun?
The orbit of the moon around Earth forms an ellipse, the distance between Earth and the moon varies over a month’s time

30. Apparent Size
The illustration, based on Galileo spacecraft images, shows the approximate difference in apparent size between a full moon at perigee (the closest point in the lunar orbit, pictured at left) and a full moon at apogee, the farthest point in the lunar orbit.

31. The near side The Moon rotates in 29.5 days.
The Moon orbits Earth in 29.5 days.
Because the Moon rotates and revolves at the same rate, we only see one side
The NEAR side
There is NO DARK SIDE
There is a FAR side….

32. Far side

33. How was the moon formed? 3 major theories
1. Capture theory: large object ventured too near the forming earth and got trapped by gravity
2. Simultaneous formation theory: Earth and moon formed at the same time.
3. Impact theory: Most widely accepted.

34. How was the moon formed? The Giant Impact Hypothesis 3 stages
1. began when a large object collided with Earth more than 4 billion years ago
2. collision ejected chunks of Earth’s mantle into orbit around Earth
3. debris eventually clumped together to form the moon.

35. Formation of the moon

36. What are phases?
Phase: in astronomy, the change in the illuminated area of one celestial body as seen from another celestial body; are caused by the changing positions of Earth, the sun, and the moon

37. Moon phases

38. Why are their phases of the moon?
Moonlight is reflected sunlight
Half the moon’s surface is always reflecting light
From Earth we see different amounts of the Moon’s lit surface
The amount seen is called a “phase”
Synchronous rotation: orbital and rotational periods are equal.

40. Waxing vs Waning Waxing – lit side is getting bigger
Waning – lit side is getting smaller
‘LEFT SIDE IS LIT, THE MOON IS LEAVING’
Left side, lit, leaving, waning

42. FOUR MAIN SHAPES
FULL
CRESCENT
QUARTER
GIBBOUS

43. For all phases: Note where the sunlight is coming from

44. Phases for the month

45. Review question
When only a small part of the moon is visible, the moon may be in its
first-quarter phase
waning-crescent phase
new moon phase
last-quarter phase

46. Why don’t we have eclipses every month?
MOON – SUN – EARTH: All do not travel in the same plane of orbit

47. What are eclipses?
an event in which the shadow of one celestial body falls on another
Bodies orbiting the sun cast long shadows into space

48. What is the shadow structure for an eclipse?
UMBRA (Latin for "shadow")
is the darkest part of the shadow
Penumbra
Umbra
PENUMBRA is a partial shadow,
grayish outer part of a sunspot

49. What is a solar eclipse?
A solar eclipse is when the moon comes between the sun and the Earth, so that a viewer is in the moon's shadow.
Total eclipses rare – only once every 360 years from one location!

50. How do I see a total solar eclipse?
Observers in the “umbra” shadow see a total eclipse (safe to view the Sun); can see the corona
Those in “penumbra” see a partial eclipse—not safe to look directly at Sun
Only lasts a few minutes
Path of Totality about 10,000 miles long, only 100 miles wide

54. The diamond ring

55. Why not a solar eclipse every month then?
Moon's orbit is tilted about 5o with respect to the Earth's orbit (ecliptic), so the shadows usually miss!
Moon
Earth
Ecliptic
Moon’s Orbit

56. What is a lunar eclipse?
the passing of the moon through Earth’s shadow at full moon
occurs when Earth is positioned between the moon and the sun and when Earth’s shadow crosses the lighted half of the moon

57. Lunar eclipse
Moon’s Path
Earth
Sun
Moon

59. Why is the Moon red during an eclipse?
The Earth’s atmosphere filters some sunlight and allows it to reach the Moon’s surface
The blue light is removed—scattered down to make a blue sky over those in daytime
Remaining light is red or orange
Some of this remaining light is bent or refracted so that a small fraction of it reaches the Moon
Exact appearance depends on dust and clouds in the Earth’s atmosphere

60. What causes the tides?
Tides: daily changes in the level of ocean water
influenced by the sun and the moon
occur in a variety of cycles
The combination of gravity and inertia create two bulges of water.
High Tide and Low Tide: How often tides occur and the difference in tidal levels depend on the position of the moon as it revolves around the Earth

61. What causes the tides?
The gravitational attraction between the Earth and the moon is strongest on the side of the Earth that happens to be facing the moon, simply because it is closer.
This attraction causes the water on this “near side” of Earth to be pulled toward the moon.
As gravitational force acts to draw the water closer to the moon, inertial force attempts to keep the water in place.
But the gravitational force exceeds it and the water is pulled toward the moon, causing a “bulge” of water on the near side toward the moon

62. On the opposite side of the Earth, or the “far side,” the gravitational attraction of the moon is less because it is farther away.
Here, the inertial force exceeds the gravitational force, and the water tries to keep going in a straight line, moving away from the Earth, also forming a bulge

63. Tides

64. Approximately how many days does it take the moon to go through a complete cycle? A. 7 B. 11 C. 26 D ow many days does it take the moon to go through a complete cycle?

65. When the visible portion of the moon is increasing, the moon is
A. waxing B. full C. waning D. waning-crescent

66. A solar eclipse is most likely to occur when the
sun is located between the earth and moon
moon is located between the sun and the earth
earth is located between the sun and the moon
earth and moon are at right angles to each other

67. Earth has seasons because
the temperature of the sun changes
Earth rotates on its axis
Earth's axis is tilted as it moves around the sun
the distance between Earth and the sun changes

68. The sun appears larger than other stars because
it is the biggest star in the universe
it is a double star
it is the closest star to the earth

69. A lunar eclipse is most likely to occur when
sun is located between the earth and moon
moon is located between the sun and the earth
earth is located between the sun and the moon
earth and moon are at right angles to each other

70. From new moon to full moon phase you see
a decreasing amount of the lighted side of the moon
an increasing amount of the lighted side of the moon
more of the lighted side, then less of the lighted side of the moon
the same amount of the lighted side of the moon

71. During what moon phase can a lunar eclipse occur?
waxing gibbous
first quarter
new moon
full moon