Astronomy Unit Chapter One: Earth, Moon, and Sun

1
Astronomy UnitChapter One Earth, Moon, and Sun

• Section One
• Earth in Space

2
Essential Question

• What effects are caused by the motions of Earth
  and the moon?

3
Objectives

• 1. Demonstrate how Earth moves in space.
• Explain what causes the cycle of the seasons.

4

• Astronomy-study of moon, stars, and other space
  objects
• How Earth Moves in Space
• -Earth moves through space in two major ways-
  rotation and revolution
• Rotation
• 1. axis- imaginary line that passes through
• Earths center and the North and South poles
• 2. rotation- spinning of Earth on its axis
• a. causes night and day
• b. rotates East to West
• c. Takes about 24 hrs. for Earth to
• rotate once 1
  day

5

• B. Revolution
• 1. Revolution- movement of 1 obj. around
• another
• 2. 1 complete revolution of Earth around sun
• 1 yr.
• 3. Orbit- elongated path Earth moves in
• around sun
• C. Calendars
• 1. Calendar- system of organizing time that
• defines beginning, length, and
  divisions
• of a yr.

6

• 2. 365 days 1 yr.
• 3. Earth orbits sun in about 365 ¼ days
• 4. Every 4 yrs there is an extra day added
• (leap year) to make up for this.
• II. The Seasons on Earth
• A. How Sunlight Hits Earth
• 1. Sunlight hits Earth most directly near
• equator warmer weather
• 2. Near poles of Earth, sunlight arrives at
• steep angles, so it is spread out
  over a
• greater area

7

• B. Earths Tilted Axis
• 1. Earth has seasons because its axis is tilted
• as it revolves around the sun
• 2. It is tilted at an angle of 23.5 degrees
• 3. As Earth revolves around sun, north end
• of its axis is tilted away from sun
  for part
• of yr.

8

• C. Earth in June
• 1. North end of Earths axis tilted toward sun
• (summer in northern hemisphere and
• winter in southern)
• D. Earth in December
• 1. Southern hemisphere receives the most
• direct sunlight (summer in southern
  
• hemisphere and winter in northern
• hemisphere)
• E. Solstices
• 1. Happen twice/yr in June and December
• 2. Solstice- Sun is farthest north or south of
• equator

9

• 3. Farthest north, summer solstice in
• northern Hemisphere and winter in
• southern hemisphere
• 4. Sun farthest south, winter solstice in
• northern hemisphere and summer
  solstice
• in southern hemisphere
• F. Equinoxes
• 1. Happen twice a yr in March and
• September
• 2. Equinox- equal night day and night are
• ea. about 12 hrs. long

10
Summary- answer the following questions in your
summary

• Explain what effects are caused by the motions of
  the Earth and moon.
• Explain the two ways Earth moves in space.
• Explain what causes the cycle of seasons on Earth.