“Win

ter

is a

n et

chin

g,

sprin

g a

wat

erco

lor,

sum

mer

an

oil

pain

ting

and

autu

mn

a m

osai

c of

them

all”

-S

tanl

ey H

orow

itz

Wha

t We

Will

Lea

rn T

oday

•W

hat c

ause

s se

ason

s on

Ear

th?

•W

hy d

o w

e se

e ph

ases

of t

he M

oon?

The

Rea

son

for

Sea

sons

Why

is s

umm

er is

hot

ter

than

win

ter?

A.

The

Sun

bur

ns h

otte

r du

ring

sum

mer

B.

We

are

clos

er to

the

Sun

dur

ing

sum

mer

C.T

he E

arth

’s a

xis

is ti

lted

with

res

pect

to

the

eclip

ticD

.Ear

th r

otat

es s

low

er d

urin

g su

mm

er,

mak

ing

for

long

er d

ays

Clu

es R

egar

ding

Sea

sons

•D

ays

are

hotte

r in

the

sum

mer

•D

ays

are

long

er in

the

sum

mer

•S

easo

ns r

epea

t with

a p

erio

d of

one

ye

ar•

Sea

sons

are

mild

nea

r th

e E

quat

or

and

seve

re n

ear

the

pole

s•

Whe

n it

is s

umm

er h

ere,

it is

win

ter

in

Aus

tral

ia!

The

Rea

son

for

Sea

sons

Why

is s

umm

er is

hot

ter

than

win

ter?

A.

The

Sun

bur

ns h

otte

r du

ring

sum

mer

B.

We

are

clos

er to

the

Sun

dur

ing

su

mm

erC

.The

Ear

th’s

axi

s is

tilte

d w

ith r

espe

ct

to th

e ec

liptic

D.E

arth

rot

ates

slo

wer

dur

ing

sum

mer

, m

akin

g fo

r lo

nger

day

s

23.5

o

Nor

ther

n H

emis

pher

e S

umm

er

Sun

’s r

ays

The

Ecl

iptic

Sum

mer

Day

s A

re H

otte

r &

Lon

ger

Nor

ther

n H

emis

pher

e S

umm

er•

Vie

w fr

om th

e S

un–

Nor

ther

n H

emis

pher

e is

tilte

d to

war

ds th

e S

un–

Can

see

mor

e of

the

Nor

ther

n H

emis

pher

e–

Can

see

it fo

r lo

nger

as

Ear

th s

pins

(da

ys a

re

lo

nger

)–

Ray

s co

ncen

trat

ed in

NH

(d

ays

are

hotte

r)

The

Sea

sons

•N

ote:

The

sea

sons

are

nam

ed fr

om th

e no

rthe

rn

hem

isph

ere’

s pe

rspe

ctiv

e

Fig

2.1

5

Sun

’s P

ath

as S

een

Fro

m E

arth

+40o

0o

+90o

Dec

linat

ion

•V

iew

from

40o

N (

say

Col

umbu

s, O

H)

•S

un a

lway

s ris

es d

ue E

ast,

right

? N

o!–

NE

in s

umm

er, S

E in

win

ter,

E a

t equ

inox

es

Fig

S1.

17

Sun

’s P

ath

from

Pol

e &

Equ

ator

•S

un r

ises

& s

ets

ever

y da

y, r

ight

?–

Not

at t

he p

oles

!

Vie

w fr

om N

pol

eV

iew

from

Equ

ator

Fig

S1.

19F

ig S

1.20

Spe

cial

Lat

itude

s on

Ear

th

Bas

ed o

n S

un’s

pat

h in

the

sky F

ig S

1.18

The

Tro

pics

•B

etw

een

the

Tro

pics

of C

ance

r an

C

apric

orn

–S

un w

ill r

each

Zen

ith a

t noo

n on

two

days

of t

he y

ear

The

Arc

tic &

Ant

arct

ic C

ircle

s

•A

t the

se c

ircle

s, th

e S

un s

tays

abo

ve th

e ho

rizon

for

at le

ast o

ne d

ay p

er y

ear

–A

lso,

bel

ow th

e ho

rizon

!

•A

t the

pol

es, w

e ha

ve th

e ex

trem

es–

6 m

onth

s of

ligh

t and

6 m

onth

s of

dar

knes

s

Fig

2.1

8

Pha

ses

of th

e M

oon

•W

hat c

ause

s th

e ph

ases

of t

he

Moo

n?•

Wha

t are

the

phas

es?

•W

hen

does

the

Moo

n ris

e &

set

?

Moo

n’s

Mot

ion

in O

ur S

ky

•R

ises

Eas

t, S

ets

Wes

t–

Due

to E

arth

’s s

pin

•M

oves

Wes

t to

Eas

t–

Due

to M

oon’

s or

bit a

roun

d E

arth

•R

esul

t–

Moo

n ris

es 1

day

and

51 m

inut

es la

ter

each

day

(on

ave

rage

)

Moo

n P

hase

Dem

onst

ratio

n

Fig

2.2

2

Moo

n’s

Syn

chro

nous

Rot

atio

n

Fig

2.2

3

Mis

nom

er: D

ark

side

of t

he M

oon