1. Earth, Moon, and Sun – Course 3
5-1 Earth in Space

2. Vocabulary
Axis- An imaginary line that passes through a planet’s center and its north and south poles, about which the planet rotates. Rotation- The spinning motion of a planet on its axis. Revolution- The movement of an object around another object. Calendar- A system of organizing time that defines the beginning, length, and divisions of a year. Solstice- Either of the two days of the year on which the sun reaches its greatest distance north or south of the equator. Equinox- Either of the two days of the year on which neither hemisphere is tilted toward or away from the sun.

3. My Planet Diary pg. 182 The Seasons:
Misconception: The seasons change because Earth’s distance from the sun changes. Fact: Seasons are the result of Earth’s tilted axis. Evidence: Earth’s distance from the sun does change, but that’s not why Earth has seasons. If that were the cause, people in the Northern and Southern hemispheres would have the same seasons at the same time. Instead, seasons in the Northern and Southern hemispheres are reversed. As Earth moves around the sun, sometimes the Northern Hemisphere is tilted toward the sun. At other times the Southern Hemisphere is tilted toward the sun.
Why are summers generally warmer than winters?
Why are the winters warmer in Florida than in Massachusetts?

4. rotation and revolution
How Does Earth Move? Pg. 183
Until a few hundred years ago, most people thought that Earth stood still and the sun, moon, and stars moved around it. But today, Scientists know that Earth itself moves and that objects seem to move across the sky because of Earth’s motion.
Earth moves in space in two major ways:
rotation and revolution

5. Rotation pg. 183
Earth moves in space in two major ways: rotation and revolution. Rotation is the spinning of Earth on its axis. Earth’s axis is an imaginary line that passes through Earth’s center and the North and South poles. The rotation of Earth causes day and night.
Draw an arrow to show the
Direction In which the Earth rotates.
Draw a line separating day from
Night.
Sequence- In which city will the
Sun set next?__________________
Challenge- Where on Earth is it
Noon? Midnight?________________
______________________________

6. Revolution pg. 184
Revolution is the movement of one object around another. One revolution of Earth around the sun is one year. Earth’s path, or orbit, around the sun is an ellipse. The ellipse brings the planet closest to the sun in January. People of many cultures have used the motions of Earth and the moon to establish calendars.

7. Calendar pg. 184
A calendar is a system of organizing time that defines the beginning, length, and divisions of a year.

8. Assess Your Understanding pg. 185
1a. Identify- Earth’s ________________causes day and night. b. Explain- How does the sun’s gravitational attraction impact Earth’s motion? ____________________________________ ___________________________________________________ c. Infer- Why do people use Earth’s motions to determine units of time? ____________________________________________ I get it! Now I know that Earth moves by ___________________

9. How Sunlight Hits Earth Pg. 186
Near the equator, sunlight hits Earth’s surface from almost overhead. Near the poles, sunlight arrives at a steep angle. As a result, near the poles sunlight is spread out over a greater area. That’s why it is warmer near the equator than near the poles.
INFER- DRAW A
CIRCLE AROUND
THE AREA WHERE
SUNLIGHT IS MOST
DIRECT. MARK AN
X ON THE PLACES
THAT SUNLIGHT
REACHES, BUT
WHERE IT IS LESS
DIRECT.

10. Earth’s Tilted Axis pg. 186
If Earth’s axis were straight up and down relative to its orbit, temperatures in an area would remain fairly constant year-round. There would be no seasons. However, Earth’s axis is tilted at an angle of 23.5˚ from the vertical. So as Earth revolves around the sun, the north end of its axis is tilted away from the sun for part of the year and toward the sun for part of the year. Earth has seasons because its axis is tilted as it revolves around the sun.
The diagram shows how
Earth moves during the
Year. It is not drawn to
Scale.
Compare the weather and
Sunlight in the Northern
And Southern hemisperes
In March and September.

11. Solstices pg. 188
The sun appears farthest north or south of the equator twice each year. Each of these days is called a solstice. In the Northern Hemisphere, the summer solstice occurs around June 21. That is the longest day of the year in the Northern Hemisphere and the shortest day in the Southern Hemisphere. Similarly, around December 21, the winter solstice occurs in the Northern Hemisphere, while the summer solstice occurs in the Southern Hemisphere.

12. Equinoxes pg. 188
Halfway between the solstices, neither hemisphere is tilted toward the sun. Each of these days is called an equinox. On an equinox, the noon sun is directly overhead at the equator, rises due east, and sets due west.

13. Solstices and Equinoxes
The diagrams show the apparent path of the sun at the solstices and equinoxes in the Northern Hemisphere. What is the sun’s path at the equinoxes and the December solstice for the Southern Hemisphere?
Draw the sun’s
Path at the
Equinoxes
And the
Winter solstice
For the
Southern
Hemisphere.

14. Do the Math! Calculating Percents
The table shows the number of hours of sunlight in three cities at different times of year. What percentage of a 24-hour day has sunlight in Miami on January 1?
Step 1- Divide the number of hours of sunlight by the total number of hours
Step 2- Multiply by 100 to find the percent
Calculate- What percentage
Of a day has sunlight in
Helsinki on July 1 ?
___________________________
2. Calculate- What is the
Difference in the percentage of
The day that has sunlight in
Helsinki and in Toronto on
January 1?
3. Infer- What percentage of the
Day would you expect to have
Sunlight at the equator in
January? In June?

15. Assess Your Understanding pg. 189
2a. Define- The noon sun is directly overhead at the equator during (a solstice/an equinox). b. What causes the seasons?_______________________________ __________________________________________________________________________________________________________ c. How would the seasons be different if Earth were not tilted on its axis? Explain. ________________________________________ I get it! Now I know that Earth’s seasons are caused by __________ ______________________________________________________