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Ch. 1 Earth, Moon, and Sun
The document discusses Earth, the Moon, and the Sun, covering topics like Earth's rotation and revolution, the reasons for seasons, phases of the Moon, and tides. It explains how Earth's orbit and axial tilt influence day/night cycles and seasonal changes, as well as detailing the phenomenon of eclipses and the characteristics of the Moon's surface. Additionally, it describes the Moon's formation, its lack of atmosphere, and the significance of gravity in these processes.
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Ch. 1 Earth, Moon, and Sun
- 2. Ch. 1 Earth, Moon,and Sun This amazing Earthrise above the moon's horizon was seen by astronaut Michael Collins in the Apollo 11 moon orbiter Columbia.
- 3. Objectives Identify the effectsof Earth’s rotation and revolution. Explain the causes of the seasons on Earth.
- 4. Section 1, Earthin Space Why Does Earth Have Day and Night?
- 5. Introduction Egyptian farmers planted their crops after the floods every year. They noticed that the star Sirius became visible before the floods. That’s when they could start predicting the floods. The Egyptians were the first people to study the stars.
- 6. Days and Years Astronomy is the study of the moon, stars, and other objects in space.
- 7. Rotation Axis - the imaginary line that passes through Earth’s center and the North and South poles. Rotation - the spinning of Earth on its axis. A point on the equator rotates at about 1,600 km per hour.
- 8. Rotation Earth’s rotation onits axis causes day and night. Earth rotates eastward. It takes 24 hours to rotate once on its axis. This is called a day.
- 9. Revolution Earth also travelsaround the sun. Revolution - the movement of one object around another object. Earth’s orbit is an oval shape.
- 10. Calendars The Egyptians countedthe number of days between Sirius stars which was about 365. Earth’s orbit around the sun is about 365 1/4 days. Four years of 365 1/4 days each can be approx. by taking 3 years of 365 days and a fourth year of 366 days. This is known as leap year. On a leap year, one extra day in February is added for 29 days.
- 11. Calendars Dividing the yearinto smaller parts (months) was difficult. Early people used the moon cycle which is 29 1/2 days but this only added up to 354. The Egyptians had a plan to have 12 months of 30 days and 5 extra days. The Romans borrowed the calendar and devised the one that we have today with 11 months of 30 to 31 days and February with 28 or 29 days.
- 12. Seasons on Earth Most places have four seasons: winter, spring, summer, and autumn.
- 13. Earth’s Tilted Axis Earth has seasons because its axis is tilted as it moves around the sun.
- 14. Earth in June The north end of Earth’s axis is tilted toward the sun. It is summer in the Northern Hemisphere and winter in the Southern Hemisphere.
- 15. Earth in December The south end of Earth’s axis is tilted toward the sun. It is summer in the Southern Hemisphere and winter in the Northern Hemisphere.
- 16. Both in Juneand December Summer solstice - longest day of the year (June 21). Winter solstice - shortest day of the year (December 21). Both of these are in the Northern Hemisphere and the opposite in the Southern Hemisphere.
- 17. Earth in March& September Neither hemisphere is tilted toward or away from the sun. So the days and nights are in an equinox which is equal.
- 18. Earth in Marchand September Vernal equinox, or spring equinox occurs around March 21 and is the first day of spring. Autumnal equinox, or fall equinox occurs around September 23 and is the first day of fall.
- 19. Solstices and Equinoxes Solsticesoccur when the sun reaches its greatest distance north or south of the equator twice each year, each of these days, when the sun is the farthest north or south of the equator. Equinoxes occur twice a year, when the noon sun is directly overhead at the equator.
- 20. Plants and Animals Plants and animals are effected by the amount of day light hours. In the spring and summer, plants grow, and animals feed on the plants. Insects and animals get more food. In the winter, animals go dormant and birds travel to warmer climates to find food.
- 21. Reasons for theSeasons
- 22. Reasons for theSeasons Lab Books, Styrofoam balls and flashlights.
- 23. Gravity and Motion Gravity gives the Universe its structure It is a universal force that causes all objects to pull on all other objects everywhere It holds objects together It is responsible for holding the Earth in its orbit around the Sun.
- 24. Inertia Galileo established the idea of inertia A body at rest tends to remain at rest A body in motion tends to remain in motion Through experiments with inclined planes, Galileo demonstrated the idea of inertia and the importance forces (friction) This concept was incorporated in Newton’s First Law of Motion : An object at rest will remain at rest, an object in motion will remain in motion in a straight line, unless acted on
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- 27. For a masson a string to travel in a circle, a force must act along the string to overcome inertia. Without that force, inertia makes the mass move in a straight line.
- 28. Phases, Eclipses, and Tides
- 29. Objectives Describe the causesof the moon’s phases. Explain what causes solar and lunar eclipses. Identify the cause of the tides.
- 30. Engage/Explore Whendoes the moon appear? Moon Rise and Set
- 31. Discover Activity How Does the Moon Move? Quarter & penny P. 20
- 32. Motions of theMoon The moon revolves around Earth and rotates on its own axis. It takes 29.5 days to revolve around Earth. The same side of the moon always faces the Earth.
- 33. The same sideof the moon always faces Earth.
- 34. Phases of theMoon Phases of the moon are seen by the reflection of the sun on the moon’s surface. The different shapes of the moon you see from Earth are called phases. The moon goes through its whole set of phases each time it revolves around the Earth, about once a month.
- 35. What Causes Phases? Phases are caused by changes in the relative positions of the moon, Earth, and the sun. The phase of the moon you see depends on how much of the side of the moon faces Earth.
- 36. The Cycle ofthe Phases of the Moon
- 37. Eclipses When the moon’sshadow hits Earth or Earth’s shadow hits the moon, an eclipse occurs. Two types of eclipses: solar and lunar
- 38. Solar Eclipses During anew moon, most of the time the moon is a little above or below the sun in the sky. A solar eclipse occurs when the moon passes between Earth and the sun, blocking the sunlight from reaching Earth. It is really a new moon that blocks your view of the sun.
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- 40. Total Solar Eclipses Umbra - the darkest part of the moon’s shadow that is cone-shaped. The point of the cone can reach a small part of Earth’s surface.
- 41. Partial Solar Eclipses Penumbra - larger part of the shadow which is more visible on Earth. During a partial eclipse, part of the sun is visible. It is not safe to look at a partial eclipse.
- 42. Solar Eclipse August 11, 1999
- 43. Total Lunar Eclipses A lunar eclipse occurs at a full moon when Earth is between the moon and the sun. Earth blocks sunlight from reaching the moon.
- 44. Total Lunar Eclipse When the moon is in Earth’s umbra, you see a total lunar eclipse. You are more likely to see a total lunar eclipse than a total solar eclipse.
- 45. Partial Lunar Eclipses Occurs when the moon passes partly into the umbra of Earth’s shadow. The edge of the shadow appears blurry and you can watch it pass across the moon for up to two or three hours.
- 46. Tides Two high tidesand two low tides occur daily, over 24 hours. The water rises for about six hours, then falls for about six hours, in a regular cycles. Tides are caused mainly by differences in how much the moon ‘s gravity pulls on different parts of earth. The Tide cycle is representing the two points of high tides due to the strength and weakness of the moon’s gravity on the earth as a whole at those points causing the tides keeping between them the other two low tides.
- 47. Gravity and Tides Low tides occur The moon’s gravity between the two causes high tide on high tides. the side closest to the moon. The force of the moon’s gravity pulls Earth toward the moon, leaving the water behind
- 48. Spring Tides andNeap Tides: Spring Tides: the combined gravity forces of the sun and moon produce a tide of the greatest difference between consecutive low and high tides, called spring tide. It happens twice a month, at new moon and at full moon.
- 49. Neap Tides During the moon’s first quarter and third quarters, the line between earth and sun is perpendicular on the line between earth and moon, so the sun’s pull at right angles to the moon’s pull produces the Neap Tides. It occurs twice a month.
- 50. Section 4, Earth’sMoon Maria In 1609, The Italian Scientist Galileo Galileo succeeded to see that the moon has an irregular surface with a variety of remarkable features that are called craters (pits), by the help of a telescope that built to Highlands observe distant objects.
- 51. The Moon’s Surface Featureson the moon’s surface include Maria, craters, and highlands. Maria; they are dark, flat areas actually hundred rock formed from lava flows from 3 or 4 billion years ago. Craters; they were caused by the impacts of meteoroids, chunks of rock or dust from space, also on Earth, some craters were disappeared due to water, wind and other forces for billions of year. Highlands; They looked as light-coloured features as the peaks of the lunar highlands and the rims of craters cast shadows, which Galileo could see by his Telescope.
- 52. Characteristics of theMoon The moon is dry and airless, compared to Earth, the moon is small and has large variations in its surface temperature.
- 53. Size and Densityof the moon Diameter; is 3, 476 km. = ¼ Earth’s diameter. 1/8 as much as mass as Earth. Its average density = density of Earth’s outer layers. Its core is less denser than Earth’s core.
- 54. Temperature and Atmosphere Temperature on the moon vary so much because it has no atmosphere. It ranges from torrid 130 °C in direct sunlight to a frigid -180 °C at night. The moon surface gravity is so weak that gases can easily escape into space.
- 55. Water There is evidencethat there may be large patches of ice near the moon’s poles. The moon has no liquid water. Some areas are shielded from sunlight by crater walls.
- 56. The Origin ofthe Moon The moon is formed by “ Collision- ring theory” that says planet-sized objects collided with Earth to form the moon. i.e. materials from the object and Earth’s outer layers was ejected into orbit around Earth, where it is formed a ring. Gravity caused these materials to combine to form the moon.