Astronomy

1. Astronomy Grade 8St. Rocco School Miss Armstrong 2014-2015

2. Section 1: Earth in space Chapter 1: Earth, Moon, and Sun

3. 1-1: Earth in Space • Astronomy: The study of the moon, stars, and other objects in space. • Egyptians were the first to study astronomy. • Use the star, Sirius, to predict yearly flooding of the Nile River.

4. 1-1: Earth in Space • Days and Years • Earth rotates around a central axis, an imaginary line that passes through the North pole to the South pole. • The rotation, or spinning of the Earth on its axis causes day and night. • Part of Earth that faces the sun experiences day. • Part of Earth that faces away from the sun experiences night.

5. 1-1: Earth in Space • 1 rotation = 1 day = 24 hours • How many hours will it take for the Earth to rotate 365 times? 1 rotation = 1 day , therefore 365 rotations = 365 days 1 day = 24 hours, therefore 365 days x 24 hours = 8,760 hours

6. 1.1 Earth in Space • Earth travels around the sun in an oval-shaped orbit. • One complete orbit around the sun is called a revolution. • 1 revolution = 1 year A child has been alive for 4,745 days. How old is this child and how many revolutions has the Earth made in his/her lifetime?

7. 1.1 Earth in Space 365 days = 1 year 4,745 days / 365 days = 13 years 1 year = 1 revolution 13 years = 13 revolutions

8. 1.1 Earth in Space • Earth’s orbit around the sun takes 365 ¼ days • Distance of Earth’s orbit: 584,000,000 miles • To account for the ¼ day, every 4 years another day is added to the calendar. • Year 1: 365 days Year 3: 365 days • Year 2: 365 days Year 4: 366 days • Year four is considered a ‘leap year’ • An additional day is added to the month of February (29 days total)

9. 1.1 Earth in Space • Egyptians tried to divide the calendar into smaller parts called ‘moonths’ based upon the phases of the moon. • The Romans divided the calendar into 2 groups • 11 months with 30 or 31 days • 1 months with 28 or 29 days (February)

10. 1.1 Earth in Space • Places outside the tropics experience four seasons: winter, spring, summer, and autumn. • When Earth is tilted towards the sun, the equator receives direct sunlight, making it warmer near the equator. • When the sunlight that hits near the poles, the light is spread out due to the shape and tilt of the Earth. This is why the poles of the Earth are cooler.

11. Earth experiences seasons because of the tilt of Earth’s axis as it revolves around the sun. When the Earth’s tilt is TOWARDS the sun: When the Earth’s tilt is AWAY from the sun: Northern Hemisphere: Winter Southern Hemisphere: Summer • Northern Hemisphere: Summer • Southern Hemisphere: Winter

12. 1.1 Earth in Space In June, the noon sun is directly overhead at 23.5° north latitude. In December, the noon sun is directly overhead at 23.5° south latitude. Those living in the Southern Hemisphere receive the most sunlight, resulting in longer and warmer days. Those living in the Northern Hemisphere receive indirect sunlight, resulting in shorter days and cooler days. • Latitude: The measurement of distance from the equator expressed in degrees north or south. • Ex.: The equator is at 0° and the North Pole is at 90° • The portion of the Earth tilted towards the sun (Northern Hemisphere) have longer days with warmer temperatures.

14. 1.1 Earth in space • On two days each year, the noon sun is either at 23.5° south OR north. • These two days are referred to as a solstice • Winter Solstice occurs when the noon sun is overhead at 23.5° in the Northern Hemisphere • Occurs around December 21 • Shortest day for Northern Hemisphere; longest in Southern. • Summer Solstice occurs when the noon sun is overhead at 23.5° in the Southern Hemisphere • Occurs around June 21 • Shortest day for Southern Hemisphere; longest in the Northern.

16. 1.1 Earth in Space • Halfway through each solstice, the length of daylight is about equal to the length of nighttime. • Occur twice a year. • The sun rises directly over the equator. • Each of these days are called a equinox. • Vernal Equinox: occurs around March 21 (Spring in Northern Hemisphere) • Autumnal Equinox: occurs around September 23 (Fall in the Northern Hemisphere)

20. Section 1.2 Phases, Eclipses, and Tides

21. 1-2: Phases, Eclipses, and tides • The Moon • Closest planet to Earth • Average distance = 384,400 kilometers or 40,200,000 football fields away. • Similar to Earth, the moon moves in space. • Revolves around the Earth • The position of the moon, Earth, and the sun causes the phases of the moon, eclipses, and tides.

22. 1-2: Phases, Eclipses, and tides • Motions of the Moon • The moon rotates on its axis and revolves around the Earth • Moon’s orbit is oval shaped • 1 revolution = 27.3 days • 1 rotation = 27.3 days • 1 year= 1 day • Act out the movement of the moon around the Earth. • How old are you on the moon? • The Earth only sees one side of the moon.

23. 1.2: Phases, Eclipses, and Tides • Phases of the Moon • The light of the moon is generated by the reflection of the light from the sun. • Example: Candle • The different shapes of the moon that are seen from Earth are called phases. • The moon undergoes many phases as it revolves around the Earth.

24. 1.2 Phases, Eclipses, and Tides • What causes phases? • Change in the position of the moon, Earth, and sun. • The sun always shines on ½ of the moon. • If that is true, why do we have period of times where we cannot observe the moon on Earth? • The phases of the moon is dependent on how much of the sunlit portion of moon is facing Earth.

26. 1.2: Phases, Eclipses, and Tides • Take some time to draw the image on page 26 in your notes. • Make sure to label what you draw! • Include color/shading

27. 1.2 Phases, Eclipses, and Tides • The Cycle of the Phases • New Moon: Side of moon that is lit faces awayfrom the Earth. • As the moon continues to revolve around Earth, more of the moon appears lit until the full moon appears. • After the full moon, the portion of the moon that is lit decreases to another new moon (approx. 29.5 days since 1st full moon).

29. 1.2: Phases, Eclipses, and Tides • Eclipse • Occurs when an object in space comes between the sun and a third object, casting a shadow on that object. • When the moon’s shadow hits Earth or Earth’s shadow hits the moon, and eclipse occurs. • Two types of eclipses • Solar • Lunar

30. 1.2 Phases, Eclipses, and Tides Solar Eclipse Lunar Eclipse Occurs when the there is a full moon and the Earth is directly between the moon and the sun. Earth blocks the sunlight from reaching the moon. • Occurs when the moon passes between the Earth and the sun, blocking sunlight from reaching Earth.

31. 1.2: Phases, Eclipses, and Tides Total Solar Eclipse Total Lunar Eclipse Similar to the moon, the Earth also has a umbra. When the moon is in Earth’s umbra, a total lunar eclipse appears. Unlike a solar eclipse, a lunar eclipse can be seen anywhere the moon is visible. • The darkest, cone shaped part of the moon’s shadow is called an umbra. • During a total solar eclipse, the sky is dark.

32. 1.2 Phases, Eclipse, and Tides Partial Solar Eclipse Partial Lunar Eclipse Most lunar eclipses, the Earth-Sun-Moon do not quite fall in line and a partial eclipse occurs. Occurs when the moon passes into the penumbra of Earth’s shadow. • The largest part of the shadow that is LESS dark than the umbra is called the penumbra • Part of the sun is visible from Earth. • People in the penumbra only see a partial eclipse.

33. Blood moon

35. Lunar Eclipse

37. 1.2 Phases, eclipses, and tides • Tides: the rise and fall of water, every 12.5 hours or so. • Tide rises for about 6.25 hours • Tide then falls for about 6.25 hours • The force of gravity pulls the moon and the Earth towards each other. • Force is dependent on mass and distance of the objects. • The tides occur mainly because of the differences in how much the moon pulls on different parts of the Earth

38. 1.2 Phases, Eclipse, and Tides • So we can conclude that the portion of the Earth closest to the Moon is experiencing high tide. • However, this means that were would only be one high tide at a time. • Is this true? • If not, explain.

39. 1.2 Phases, Eclipse, and tides

40. 1.2 Phases, Eclipses, and tides • The Tide Cycle • At any point in time, two places are experiencing high tide and two other places are experiences low tide. • How many tides occur in an approximately 24 hours time period? • Four (Two high tides and two low tides). All four occur in a 25 hour cycle.

41. 1.2 phases, eclipses, and tides • The sun’s gravity also affects Earth’s waters. • When the Earth-sun-moon (new moon) align, the gravity of the sun and moon pull the water in the same direction. • The combined forces produce a spring tide. • CAN THIS ALSO HAPPEN DURING A FULL MOON? • When the Earth-sun-moon (full moon) are positioned at a right angle, the water is pulled in two different directions. • This produces a tide with the least difference between low and high, called neap tide.

42. Earth’s moon Chapter 1 Section 4

43. 1.4 Earth’s Moon • For this section’s notes, create a Venn diagram Moon’s surface Earth’s surface

44. 1.4 Earth’s Moon • Features of the moon include: • Temperatures ranging from -170°C to 100°C • No air • No liquid water • Why does liquid water not exist on the moon? • In order for humans to investigate the moon, heavy spacesuits and air supply equipment is required.

45. 1.4 Earth’s Moon • Structure of the moon • 3,476 kilometers in diameter • Diameter is slightly less than the USA • ¼ of Earth’s diameter. • Mass of the moon is 1/8 as much as Earth. • Dense core with less dense outer layers • Average density of the Moon is about the same compared to Earth’s outer layers

46. 1.4 Earth’s Moon • Origin of the moon • Hypothesis 1 • The Earth spun so fast that material was flown off and became the moon • Hypothesis 2 • The moon was elsewhere in the solar system and Earth’s gravitation pull captured it as it came near. • Hypothesis 3 • Earth and moon were formed at the same time. • All of these ideas were rejected by scientists.

47. 1.4 Earth’s Moon • Origin of the moon • The theory that best fits is the collision theory • Occurred approximately 4.5 bya • An object the size of Mars collided with Earth • Material from the collision was thrown into orbit, formed the moon.

48. 1.4 Earth’s Moon • Observing the moon • Galileo Galilei used a device known as a telescope to observe objects at a distance. • A telescope is composed of two lenses in a wooden tube that focus light coming through the tube, making distant objects appear closer. • Galileo was able to observe the moon in more detail than anyone had ever seen it. • Galileo observed craters, highlands, and maria on the Moon’s surface

49. 1.4 Earth’s Moon • Galileo also observed highlands, or mountains. • The highlands and craters cast shadows along the Moon’s surface, which are observable.

50. 1.4 Earth’s Moon • Most of the moon’s surface is covered with round pits called craters. • Scientists believe these craters were created from volcanoes. • Today, we know that these craters are created from impact of meteoroids, rocks from space.