Seasons and Tilt

Objective: To learn the different seasons, and what causes them.

Define “Rotation” at the top of your paper.

“Rotation”: The spinning of the planet on its axis.

“Revolution”: Means going in an orbit around the sun.

Why is it that during the summer its hot, & yet during the winter it is cold?

Most adults would say its because the Earth is closer to the Sun during the summer-so its hotter.

& that the Earth is farther from the Sun during the Winter—so its colder.

Winter Summer

Farther Away CloserSunE E

Turns out that, that is totally false, & back wards. We are farther away in the summer & closer in the winter.

WinterSummer

Farther Away CloserSunE E

Its Reverse of the other diagram.

How could we be hotter when we are farther away during the summer?

It is because of Earth’s TILT, & the proportion of the Sun’s rays that reach the Earth.

To outside of orbit is: Night

Notice the dashed “orbit line”. Note to the outside it is Night time. Label the top right corner.

Notice the dashed “orbit line”. Note to the inside it is Day time. Label the bottom right corner.

To inside of orbit is: Day

Color Code the Sun Yellow in the center.

Sun

Notice: At the Dec. 22 position the Earth is tilted away from the Sun. Label this above the Sun.

N. Hemisphere TiltedAway

Sun E

Dec. 22

Earth is tilted away from the Sun=Winter.

Notice on Dec. 22 in the diagram that most of the Sun’s rays hit the Earth from the equator to the S. Pole.

MostFew

Dec. 22

Sun

Color code from the equator to the South Pole “Dark” Orange below the dashed orbit line.

MostFew

Dec. 22

Sun

Since “Most” (70%) of the rays hit in the Southern Hemisphere that’s where it would be “summer”.

Label that part of your diagram Summer.

Dec. 22

Sun

SummerAway

Now color code from the equator to the North Pole Light Orange below the dashed orbit line.

Dec. 22

Sun

SummerAway

Label that section “Winter” on your diagram.

Dec. 22

Sun

SummerAway

Winter

Color code above the dashed orbit line dark blue, in the Northern Hemisphere.

Color code above the dashed orbit line light blue, in the Southern Hemisphere.

Note that during the summer we have long days (dark orange) and short nights (light blue).

Its reverse during the winter we have short days (light orange) and long nights (dark blue).

Color code to the inside of the dashed orbit line medium orange, at the Mar. 22 Position.

Sun

Mar. 22

Earth is tilted sideways (not pointing toward or away

from Sun)=Spring.

E

Color code to the outside of the dashed orbit line medium blue, at the Mar. 22 Position.

Label the Northern Hemisphere Spring & the Southern Hemisphere Fall on your diagram.

Fall

Spring

Notice we have 12 hrs. of light, & 12 hrs. of dark, during Fall & Spring. Label this on your paper.

Fall

Spring12hrs. Light

12hrs Dark

Go to the bottom of your paper & define Equinox: Equal amounts of light & darkness, 12hrs. of each.

Now label the left side of the Mar. 22 position Vernal (Vernal means Spring) Equinox.

Fall

Spring

Ver

nal

Eq

uin

ox

Your diagram should look like this now.

Fall

Spring

Ver

nal

Eq

uin

ox SummerWinter

Away

Label below the Sun that the N. Hemisphere is tilted “Toward” the Sun.

Fall

Spring

Ver

nal

Eq

uin

ox SummerWinter

Away

Toward SunN. Hemisphere Tilted

Sun

June 22

Earth is tilted toward the Sun=Summer.

E

Color code to the inside of the dashed orbit line dark orange, in the Northern Hemisphere at the June 22 position

Color code to the inside of the dashed orbit line light orange, in the Southern Hemisphere.

Now label the June 22 position Summer in the Northern H. & Winter in the S. Hemisphere.

Summer Winter

June 22

Color code to the outside of the dashed orbit line dark blue for winter & light blue for summer.

June 22

Earth is tilted sideways (not pointing toward or away from the Sun=Fall.

Sun

E

Sept. 22

Color code to the inside of the dashed orbit line medium orange, & to the outside medium blue, at the Sep. 22 position.

Label the Northern Hemisphere Fall & the Southern Hemisphere Spring at the Sept. 22 position.

Fall

Spring

Notice we have 12 hrs. of light, & 12 hrs. of dark, during Fall & Spring. Label this on your paper.

Fall

Spring

12hrs. Light12hrs Dark

Label the right side of the Sept. 22 position Autumnal Equinox.

Fall

Spring

Au

tum

nal

Eq

uin

ox

Your diagram should look like this now.

Fall

Spring

Ver

nal

Eq

uin

ox SummerWinter

Away

Sun

Toward

Summer Winter

Fall

Spring

Au

tum

nal

Eq

uin

ox

Go to the bottom of your paper and define Solstice.

Solstice: This is where the Earth reaches the 2 farthest ends of the ellipse orbit.

Sun

Summer Solstice

Earth is tilted toward the Sun=Summer Solstice.

E E

Winter Solstice

June 22 Dec. 22

Earth is tilted away from the Sun=Winter Solstice.

From the Earth the Sun sets the farthest South during a Winter Solstice, & the farthest North during a Summer Solstice.

Solstice: This is where the Earth reaches the 2 farthest ends of the ellipse orbit.

Go above the Dec. 22 Position & label it Winter Solstice, & below the June 22 position & label it Summer Solstice.

Fall

Spring

Ver

nal

Eq

uin

ox SummerWinter

Away

Sun

Toward

Summer Winter

Fall

Spring

Au

tum

nal

Eq

uin

ox

Winter Solstice

Summer Solstice

Now color code the tip end of each Arctic North & South Pole Red at each position.

Note: To the outside of the orbit line at the Winter & Summer Solstice positions it is dark 24 hrs. a day. Label this.

24 hrs Dark

24 hrs. Dark

Note: To the inside of the orbit line at the Winter & Summer Solstice positions it is light 24 hrs. a day. Label this.

24 hrs. Light

24 hrs. Light

Now answer the questions on the Left side of notebook.

In illustration (a) the northern hemisphere would be experiencing what season?________

Sun’s Rays Date:_________

(a)

_______________

In illustration (b) the northern hemisphere would be experiencing what season?________

_______________

Sun’s Rays

Date:_________

(b)

Draw a diagram and write down what season is being described.

(a) The number of daylight hours equals the number of hours of darkness.

_______________

Sun’s Rays

Date:_________

How did ancient people know the seasons of the year, or when a new

year had come?

OBSERVATIONS!!!OBSERVATIONS!!!

Chaco Canyon, NM

Summer Solstice

Winter Solstice

Equinox

Casa Grande Ruins Coolidge Arizona

It is the only Native American ruin structure of its kind in the U.S. The Casa Grande dates to approximately A.D. 1300-1400 and includes calendar holes in the walls which let in light at specific times of the year, such as the summer solstice and the fall and spring equinox.

SinaguaPetroglyphs

The Vernal and Autumnal Equinox aligns three concentric circles

The full corn planting is marked in the third week of May by

concentric circles and the corn stalk centered in the sun shaft.

The Summer Solstice is marked when the concentric circles

frame the upper shadow line, and the lower line stops at the dancers

The Winter Solstice is marked by the sun's appearance at the

lowest point between the petroglyph panel and the stone pillar.

Closure

• Write 2-3 complete sentences explaining,

• What is happening at the solstices with light?

• What is happening during the equinoxes with light?