how and why wonder book of time

8/11/2019 How and Why Wonder Book of Time

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T H E H O W A N D W H Y W O N D E R B O O K O F

T I M E

W r i t t e n b y G E N E L I B E R T Y

I l l u s tr a t e d b y J O K O T U L A

E d i t o r i a l P r o d u c t i o n : D O N A L D D . W O L F

E d i t e d u n d e r t h e s u p e r v i s i o n o f

D r . P a u l E . B l a c k w o o dW a s h i n g t o n , D . C .

Te x t a n d i l l u s t r a t io n s a p p r o v e d b y

O a k e s A . W h i t e

B r o o k l y n C h i l d r e n ' s M u s e u m ,

B r o o k l y n , N e w Y o r k

W O N D E R B O O K S N E W Y O R K


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I n t r o d u c t i o n

W h a t i s t i m e ? T i m e i s s o m e t h i n g e l u s i v e w h i c h i s a t t h e c e n t e r o f o u rd a y t o d a y a c t i v i t i e s . S o m e t i m e s w e s a y t i m e f l i e s ; s o m e t i m e s w e s a y i t d r a g s .W e c a n n o t s e e t i m e o r f e el it o r h e a r i t . B u t w e c a n m e a s u r e i t .

Ti m e , i t h a s b e e n s a i d , is t h e i n t e r v a l b e t w e e n e v e n t s . T o m e a s u r e t i m ey o u m u s t s e l e c t r e g u l a r l y o c c u r i n g e v e n t s a n d t h e n d e v i s e w a y s o f m e a s u ri n g t h e in t e r v a l s b e t w e e n t h e i r o c c u r r e n c e a n d r e o c c u r r e n c e . The How andWhy W onder Book of Time t e l ls o f m a n ' s s e a r c h t h r o u g h t h e a g e s f o rp r a c t i c a l w a y s o f m e a s u r i n g t h e s e i n t e r v a l s . T h i s b o o k a l s o t e l l s h o w t i m ei s i m p o r t a n t t o e a c h o f u s a n d p a r t i c u l a r l y t o s c i e n t is t s i n t h e i r u n e n d i n gq u e s t f o r n e w k n o w l e d g e a b o u t t h e u n i v e r s e .

T h e i n v e n t i v e n e s s o f p e o p l e i s d e m o n s t r a t e d b y t h e m a n y k i n d s ofc l o c k s t h a t h a v e b e e n d e v e l o p e d . D o y o u k n o w h o w a b u r n i n g r o p e o r aw a t e r c l o c k o r a m o l e c u l a r c l o c k t e ll s t i m e ? C o u l d y o u m a k e a s u n d i a l , ac a n d l e c l o c k o r a s a n d g l a s s ? The How and Why Wonder Book of Timea n s w e r s t h e s e q u e s t i o n s a n d m a n y m o r e , a n d a l s o g i v e s y o u i n s t r u c t i o n s f o rm a k i n g y o u r o w n c l o c k s . T h i s b o o k , s t u d i e d a t h o m e a n d i n s c h o o l , w i l le n l i g h t e n y o u n g r e a d e r s a b o u t m a n y f a s c i n a t i n g a s p e c t s o f m a n ' s p r e o c c u p at i o n w i t h t h e " i n t e r v a l b e t w e e n e v e n t s . "

Paul E. Blackwood

Dr. Blackwood is a professional employee in the U. S. Office of Education.This book was edited by him in his private capacity and no official support orendorsement by the Office of Education is intended or should be inferred.


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C o n t e n t s

S E C O N D S A N D C E N T U R I E S 5

H o w d id m en f i rs t t e l l t im e? 5W h a t d o s h a d o w s te ll u s a b o u t t i m e ? 6

C A L E N D A R S O L D A N D N E W 7

W h o w e r e t h e t i m e t e l le r s o f B a b y l o n ? 7W h y d o w e h a v e tw e l v e m o n t h s ?W h a t i s u n u s u a l a b o u t t h e n u m b e r

s ix ty?C o u l d w e h a v e a t w e n t y o r a f o r t y

h o u r d a y ?

H o w w e r e t h e d a y s n a m e d ?W h y d o w e h a v e l e a p y e a r s ?W h y d i d E g y p t i g n o r e t h e l e a p y e a r ?H o w w a s t h e c a l e n d a r a b u s e d b y

R o m a n o f f ic i al s ?W h a t w a s w r o n g w i t h t h e J u l i a n

C a l e n d a r ?T h e m o n t h s o f t h e y e a rH o w d i d a " w a n d e r i n g h o l i d a y " g i v e

u s o u r p r e s e n t c a l e n d a r ?W a s G r e g o r y ' s c a l e n d a r a c c e p t e d

b y t h e w o r l d ?W h y d o w e o b s e r v e a S a b b a t h ?W h y is t h e M o s l e m C a l e n d a r

c o n f u s i n g ?H o w a r e s o m e O r i e n t a l C a l e n d a r s

a r r a n g e d ?W h a t w a s t h e M a y a n C a l e n d a r l i k e ?Wo u l d y o u p r e f e r t h e Wo r l d

C a l e n d a r ?

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2 0

T I M E I N T H E S O L A R S Y S T E M 2 1

H o w f a r d o e s t h e e a r t h r o t a t e i no n e h o u r ? 21

W h e n d o t h e s u n ' s r a y s s l a n t t h em o s t ? t h e l e a s t ? 2 2

W h e r e d o e s a y e a r e q u a l a d a y ? 2 2W h a t i s a l i g h t y e a r ? 2 2C a n w e r e l y o n t h e s u n t o m e a s u r e

t i m e ? 2 3W h y d o w e u s e a n i m a g i n a r y s u n

f o r t i m e k e e p i n g ? 2 3W h a t i s a s t a n d a r d t i m e z o n e ? 2 3

W h e r e is t h e t i m e c e n t e r f o r t h ew h o l e w o r l d ? 2 6

S t a n d a r d t i m e s i n d i f f e r e n t c i t i e so f t h e w o r l d 2 7

H o w c a n y o u l o s e o r g a i n a d a y ? 2 8W h a t i s s t a r t i m e ? 2 8W h y i s s t a r t i m e u n p r a c t i c a b l e ? 2 8W h a t t i m e s y s t e m i s u s e d b y t h e

a r m e d s e r v i c e s ? 2 9H o w a r e t h e h o u r s o f d a y l i g h t

i n c r e a s e d ? 2 9H o w t o c h e c k y o u r w a t c h b y t h e s t a r s 3 0

H o w t o f i n d d i r e c t i o n s b y u s i n g y o u rw a t c h a n d t h e s u n 31

T I M E K E E P E R S F R O M F I R ET O T H E A T O M 3 2

H o w d id f ire he lp to t e l l t im e? 32W h e r e d o e s t h e r o d o f a s u n d i a l

p o i n t ? 3 2H o w t o m a k e a c a n d l e c l o c k 3 4H o w t o m a k e a s u n d i a l 3 5H o w w e r e m o v i n g s a n d a n d m o v i n g

w a t e r u s e d t o m e a s u r e t i m e ? 3 6M a k e y o u r o w n w a t e r c l o c k 3 8H o w t o m a k e a s a n d g l a s s 3 8H o w d i d t h e f i r s t m e c h a n i c a l c l o c k s

l o o k ? 3 9W h a t a r e t h e f o u r p a r t s u s e d in a l l

c l o c k s a n d w a t c h e s ? 3 9H o w w e r e c l o c k s r e d u c e d i n s i z e? 4 0W h y a r e p e n d u l u m c l o c k s s o

a c c u r a t e ? 4 1H o w m a n y t i m e s d o e s y o u r w a t c h

t ick in a da y ? 4 2W h a t is a r a d i o c a r b o n c l o c k ? 4 2H o w o l d i s a n c i e n t J e r i c h o ? 4 2W h a t t y p e of m o t i o n is u s e d i n a l l

c l o c k s o f t o d a y ? 4 3H o w d o e s a n a t o m i c c l o c k w o r k ? 4 4W h y i s t i m e f r e q u e n t l y c a l l e d t h e

f o u r t h d i m e n s i o n ? 4 6W h a t d o e s t i m e t e ll u s ? 4 6

S P E C I A L W O R D S 4 7


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Early man observed tthe cycle of the phasof the moon from moon to new moand back to full malways took the saamount of time.


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S e c o n d s a n d C e n t u r i e s

T i m e is m e a s u r e d b y t h e j o u r n e y o f o u r p l a n e t t h r o u g h s p a c e . T h e e a r t h ' s

y e a r l y t r i p a r o u n d t h e s u n , t h e m o n t h l y o r b i t o f t h e m o o n , a n d t h e d a i l y r o t a t i o n

o f t h e e a r t h o n it s a x i s g i v e u s a s t a n d a r d f o r t h e l e n g t h o f t h e y e a r , t h e m o n t h

a n d t h e d a y . L i k e g r a v i t y a n d t h e a t o m , t i m e i s o n e o f t h e g r e a t n a t u r a lp h e n o m e n a t h a t w e a r e l e a r n i n g t o e x p l o r e a n d u n d e r s t a n d .

T i m e h a s a q u a l i t y t h a t i s a s h a z y a n d d i s t a n t a s a n i g h t s k y b e f o r e r a i n .

T h e h a z e o c c a s i o n a l l y c le a r s f o r o n e o f o u r s c i e n t is t s o r p o e t s , a n d t h r o u g h t h e m

a g l i m p s e o f t h e s t r u c t u r e o r m e a n i n g o f t i m e i s r e v e a l e d .

A l t h o u g h o u r k n o w l e d g e of t i m e i s g r o w i n g , a n d w e c a n a c c u r a t e l y

m e a s u r e i t s p a s s a g e , t i m e i ts e lf r e m a i n s a l o o f f r o m o u r c o n t r o l . M e n h a v e n e v e r

b e e n a b l e t o c h a n g e t i m e . I t i s t i m e t h a t h a s p e r m i t t e d m e n t o s e e c h a n g e .

P r i m i t i v e m a n r e s p o n d e d t o t h e p a s s i n g

o f t i m e o n l y a s i t

p a c e d t h e s p a n of h i s

s u r v i v a l . D a y l i g h t w a s

a p e r i o d f o r h i m t o h u n t f o o d , a n d d a r k -

How did menfirst tell time?

n e s s a l l o w e d r e s t . H e k n e w t h e o v e r a l l

s e a s o n a l r h y t h m s w h e n t h e y b r o u g h t

d i f f e r e n t p e r i o d s o f n i g h t a n d d a y, e x

t r e m e s o f h o t a n d c o l d , a n d a s h i f t i n

t h e b o u n t y of g a m e a n d p l a n t f o o d . U l -

A large circle of monoliths orvery large stones stands atStonehenge, in England. Formany centuries no one reallyknew where the stones came

from and for what purposethey were put there. Todaysome scholars think thatStonehenge was a calendarfor one da y. This day wasabout June 22, the summersolstice (the longest day ofthe year) 4000 years ago.The heel stone, slaughterstone and altar stone wereapparently arranged so thatthey pointed toward the rising sun only on this day.


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t i m a t e l y t h e g r o w t h o f h i s c h i l d r e n a n d

t h e a g i n g of h i s b o d y r e v e a l e d t o h i m

t h a t h e h a d l i v e d t h r o u g h a g r e a t m a n y

n i g h t - a n d - d a y c y c l e s a n d s e a s o n a l

c h a n g e s . Y e a r s w e r e a c c u m u l a t i n g .

A s t h e h u m a n r a c e e v o l v e d , t r ib e s b e

c a m e o r g a n i z e d . T h e r e w a s a n e e d t o

c o o r d i n a t e h u n t i n g p a r t i e s , c o u n c i l s a n d

r e l i g io u s c e r e m o n i e s . W h e n d o w e m e e t ,

w h e n d o w e t a l k , w h e n d o w e a p p e a l

t o o u r g o d s ? A m e a s u r e m e n t o f t i m e

t h a t e v e r y b o d y c o u l d u s e w a s r e q u i r e d ,

a n d s o m e w h e r e b a c k in o u r h i s t o r y , l o n g

b e f o r e t h e a g e s o f m e t a l o r t h e w r i t t e n

r e c o r d , t i m e - t e l l i n g s t a r t e d .

T h e m e a s u r e m e n t of t i m e p r o b a b l y

b e g a n w i t h o b s e r v a t i o n s b a s e d o n t h e

m o v e m e n t s o f t h e s u n a n d t h e m o o n .

T h e r i s i n g a n d s e t t i n g o f t h e s u n m a r k e d

t h e d a y . I n t h e e v e n i n g s , c e r e m o n i e s a r

r a n g e d t o s t a r t w h e n t h e m o o n w a s f u ll

o r p a r t l y v i s i b l e , g a v e m e n a b r o a d e r

m e a s u r e o f t i m e .

I n t h e i n t e r v a l f r o m f u l l m o o n t o f u l l

m o o n , a p p r o x i m a t e l y 2 9 Vi d a y s w e r e

c o u n t e d . T h e n m e n b e g a n t o r e c o r d

t h e s e m o o n - m o n t h s a n d d i s c o v e r e d t h a t

1 2 o f t h e m a d d e d u p t o a f u l l c y c l e o f

t h e f o u r s e a s o n s . T h e a r i t h m e t i c o f o u r

o w n c a l e n d a r w a s s l o w l y d e v e l o p i n g .

What do shadowstell us about time?

S h a d o w s c a s t b y t h e c h a n g i n g p o s i t i o n

o f t h e s u n a r e

o n e o f t h e s i m

p l e s t w a y s t o

m e a s u r e t h e d a y . M e n o b s e r v e d t h a t

m o r n i n g a n d e v e n i n g s h a d o w s w e r e t h e

l o n g e s t a n d t h a t a t n o o n , w h e n t h e s u n

i s o v e r h e a d , t h e s h a d o w i s t h e s h o r t e s t .

T h e f ir s t s u n d i a l s w e r e t r e e s a n d r o c k s

a n d t h e n , p e r h a p s , a s t r a i g h t b r a n c h s e ti n t h e c e n t e r o f a c i r c l e o f r o c k s . H o u r s

w e r e a s y e t u n k n o w n , b u t m e n h a d

l e a r n e d t o d i v i d e t h e t i m e b e t w e e n s u n

r i s e a n d s u n s e t i n t o s m a l l e r p e r i o d s .

Fragments of stonefound in the ruins ofancient Babylonia show

what appears to be anincised (cut in) designof a map. The earthappears as a disc.

The astronomer-priests of Babylonia were keen observers of the stars and had a broad knowledge ofastronomy. ^


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C a l e n d a r s O l d a n d N e w

O v e r m a n y t h o u s a n d s o f y e a r s , p r i m i t i v e w a y s o f l if e g r a d u a l l y w e r e

r e p l a c e d b y t h e d e v e l o p m e n t o f c i v i l i z a t i o n . C i t i e s t o o k f o r m , l e a r n i n g a n d

k n o w l e d g e i n c r e a s e d i n i m p o r t a n c e , t r a d e r e a c h e d t o f a r a r e a s , a n d s k i l le d

c r a f t s m u l t i p l i e d . L i f e b e c a m e m o r e c o m p l i c a t e d a n d m e n b e g a n t o s e e k b e t t e r

w a y s o f t e l l i n g t i m e t o g u i d e t h e i r a c t i v i t i e s .

O n e o f t h e f ir st g r e a t a d v a n c e s i n t i m e

t e l l i n g w a s t h eW h o w e r e t h e t i m e , , , ,

r e m a r k a b l e lu-t e l l e r s o f B a b y l o n ?

n a r ( m o o n )

c a l e n d a r o f t h e a n c i e n t B a b y l o n i a n s .

T h e s t u d y o f t h e h e a v e n s a m o n g t h e s e

p e o p l e o f t h e E u p h r a t e s Va l l e y w a s c a rr i e d o n b y t h e a s t r o n o m e r - p r i e s t s , w h o

b l e n d e d s u p e r s t i t i o n w i t h b r i l l i a n t a s

t r o n o m y .

R e l i g i o u s p r o p h e c y a n d g u i d a n c e

p r o v e d t o b e p r o f i t a b l e o c c u p a t i o n s

#

a m o n g a n u n e d u c a t e d p e o p l e . T h e

a s t r o n o m e r - p r i e s t s m a n i p u l a t e d t h e i r

s t a r c h a r t s t o b r i n g t h e m w e a l t h a n d

p o l i t i c a l a u t h o r i t y . Y e t m u c h o f t h e i r

s c i e n c e of t h e s k ie s , a c h i e v e d w i t h o u t

t e l e s c o p e s o r f in e i n s t r u m e n t s , w a s s o

p r a c t i c a l a n d r e l i a b l e t h a t w e s t il l u s e

i t t o d a y .

T h e a s t r o n o m e r - p r i e s t s c a r e f u l l y s e p

a r a t e d t h e h e a v e n s i n t o a g i a n t c i r c u l a r

b a n d o f 1 2 e q u a l d i s t a n c e s c a l l e d t h e

zodiac. E a c h d i s t a n c e w a s i d e n t i f ie d

b y a c o n s t e l l a t i o n , o r c l u s t e r of s t a r s ,

t h a t s e r v e d a s a s i g n p o s t t o p o i n t o u t

t h e r o u t e o f t h e s u n a s i t s e e m e d t o

p a s s f r o m o n e c o n s t e l l a t i o n t o t h e n e x t .

A c t u a l l y t h e a s t r o n o m e r - p r i e s t s d i d

n o t k n o w t h a t i t w a s t h e m o v e m e n t o f

A Babylonian stone cutter makes a ca lenda r basedon the observations of the moon by the astronomers.


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t h e e a r t h t h a t m a d e t h e s u n a p p e a r t o

b e i n m o t i o n . U n l i k e t h e p a s s e n g e r w h o

r e a l i z e s t h a t i t i s a c t u a l l y h i s t r a i n t h a t

i s m o v i n g w h e n t h e l a n d s c a p e s e e m s t o

r u s h p a s t , t h e a s t r o n o m e r - p r i e s t s w e r e

d e c e i v e d b y o u r i n a b i l i t y t o s e e t h e e a r t h

m o v e .

T h e s u n t o o k o n e y e a r t o c o m p l e t e i t s

a p p a r e n t c y c l e

t h r o u g h t h e 1 2

s e c t i o n s o f t h e z o

d i a c . T h e s o l a r y e a r w a s d i v i d e d i n t o 12

Why do we havetwelve months?

The Babylonian astronomer-priests dividedspace as well as tim

Names and figuresdesignating the constellations of the zodiacare still the same. Thenner band shows the

Greek signs which westill use today.

THE TWELVE CONSTELLATIONS OF THE ZODIAC

L i b r a , t h e B a l a n c er i e s , t h e R a m

T a u r u s t h e B u l l

G e m i n i , t h e T w i n s

C a n c e r , t h e C r a b

L e o , t h e L i o n

V i r g o , t h e V i r g i n

p a r t s . T h e r e w e r e n o w 1 2 d i v i s i o n s o f

t h e y e a r , e a c h a n i n t e r v a l o f t i m e m a t c h

i n g t h e 1 2 z o d i a c m e a s u r e m e n t s o f

d i s t a n c e .

T h e t i m e i t t o o k f o r t h e s u n t o t r a v e l

b e t w e e n t w o c o n s t e l l a t i o n s o f t h e z o d i a ca l s o r o u g h l y e q u a l l e d t h e t i m e r e q u i r e d

b y t h e m o o n t o c o m p l e t e a ll o f i ts

p h a s e s . B o t h d u r a t i o n s o f t i m e w e r e

w h a t w e n o w c a l l a m o n t h . W i t h t h e

t w o h e a v e n l y b o d i e s i n a g r e e m e n t , t h e

y e a r b e c a m e 3 6 0 d a y s o f 1 2 e q u a l

m o n t h s , e a c h m o n t h c o n t a i n i n g 3 0 d a y s .

T h e z o d i a c i s s t il l u s e d b y a s t r o n o

m e r s t o m a p t h e s k i e s a n d a l s o b y p r e s

e n t d a y a s t r o l o g e r s , w h o h a v e k e p t a l i v e

t h e h e a v e n l y s u p e r s t i t i o n s o f t h e B a b y

l o n i a n p r i e s t s . T h e y u s e t h e z o d i a c s i g n s

t o p r e d i c t t h e f u t u r e o f h u m a n a f f a ir s .

I n c u r r e n t E n g l i s h , w o r d s l i k e saturnine

moon-struck, ill-starred lunatic a n d

capricious a r e p a r t o f t h e s u p e r s t i t i o u s

i n h e r i t a n c e o f a s t r o l o g y .

S c o r p i o , t h e S c o r p i o n

S a g i t t a r i u s , t h e A r c h e r

C a p r i c o r n u s , t h e G o a t

A q u a r i u s , t h e W a t e r c a r r i e r

P i s c e s , t h e F i s h e s

8


11/52

The diagram above shows the sun (center), the earth and its orbit, and the apparent circle the constellations ofthe zodiac seem to make around the solar system.

T h e B a b y l o n i a n s u s e d t h e n u m b e r 6 0

f o r t h e s t a n -W ha t i s unusual about . . ,.j . , . 0 d a r d o f mea-the number sixty?

s u r e i n b o t h

c i vi l a f fa i rs a n d a s t r o n o m y . A l t h o u g h6 0 w a s a m y s t i c n u m b e r , i t w a s a s i m

p o r t a n t t o s c i e n c e a s i t w a s t o r e l i g i o n .

S i x t y h a s g r e a t v e r s a t i l i t y b e c a u s e i t c a n

b e d i v i d e d b y m o r e n u m b e r s t h a n a n y

o t h e r l o w e r n u m b e r . T h i s e a s e o f d iv i

s i o n m a d e 6 0 a n e x c e l l e n t c h o i c e f o r

s c ie n ti f i c m e a s u r e m e n t .

D a y a n d n i g h t w e r e e a c h a s s i g n e d 1 2

h o u r s i n r e c o g n i t i o n o f t h e p o w e r o f t h ez o d i a c . T h e n u m b e r of m i n u t e s i n a n

h o u r w a s t h e n s e t a t 6 0 , a n d e a c h m i n

u t e w a s s u b d i v i d e d i n t o 6 0 s e c o n d s . I f

y o u l o o k a t y o u r w a t c h , y o u w i l l s e e

h o w n a t u r a l l y 5 m i n u t e p e r i o d s , q u a r t e r -

h o u r s a n d h a l f - h o u r s a r e d i v i d e d . C o m

b i n a t i o n s l i k e 1 0 , 2 0 o r 4 0 m i n u t e s a r e

r e v e a l e d a t a g l a n c e .

T h e a s t r o n o m e r - p r i e s t s d i v i d e d s p a c e

a s w e l l a s t i m e . T h e y s p l i t t h e c i r c l e i n t o

3 6 0 d e g r e e s . E a c h d e g r e e h a d 6 0 m i n

u t e s , a n d e a c h m i n u t e h a d 6 0 s e c o n d s .

T h e w e e k a n d t h e h o u r a r e i n v e n t i o n s o fs u p e r s t i t i o n a n d

C o u l d w e h a v e c o n v e n i e n c e . T h e

* W 6 | i > d a y , t h e m o n t h a n df o r t y h o u r d a y ? "

t h e y e a r d e p e n d o n

t h e m o v e m e n t o f b o d i e s i n s p a c e , b u t

t h e w e e k a n d t h e h o u r a r e a r t i f i c ia l

m e a s u r e m e n t s t h a t h e l p u s t o o r g a n i z e

o u r o w n a c t i v i t i e s w i t h o u t a n y d i r e c t i o n

f r o m n a t u r e . W e p r o b a b l y c o u l d l iv ej u s t a s c o m f o r t a b l y if o u r d a y w e r e

d i v i d e d i n t o 2 0 o r 4 0 u n i t s a n d o u r w e e k

i n t o 6 o r 8 u n i t s . B u t 2 4 h o u r s a n d 7

d a y s a r e t h e u n i t s t h a t h a v e b e e n w i t h

u s a l o n g t i m e , a n d a c h a n g e t o n e w

u n i t s i s u n l i k e l y . T h e a n c i e n t S c a n d i

n a v i a n s , h o w e v e r , h a d a 5 d a y w e e k ,

a n d s o m e t r i b e s i n A f r i c a s t i ll u s e w e e k s

o f 3 , 4 , 5 , 6 a n d 8 d a y s .


12/52

ENGLISH

S u n d a y

M o n d a y

T u e s d a y

W e d n e s d a y

T h u r s d a y

F r i d a y

S a t u r d a y

THE DAYS OF THE WEEK

ANGLO-SAXON

S u n ' s d a y

M o o n ' s d a y

T i w ' s d a y ( N o r s e g o d o f w a r )

W o d e n ' s d a y ( N o r s e g o d o f s t o r m s )

T h o r ' s d a y ( N o r s e g o d o f t h u n d e r )

F r i g g ' s o r F r e y a ' s d a y( N o r s e g o d d e s s o f l o v e )

S a t e r ' s d a y ( f r o m S a t u r n , t h e

R o m a n g o d o f a g r i c u l t u r e )

J ..:.

T h e B a b y l o n i a n w e e k h o n o r e d t h e s u n ,

t h e m o o n a n d t h eH o w w e r e t h e , , . . - , 5 p l a n e t s t h a t w e r e

d a y s n a m e d ? r

k n o w n a t t h e t i m e .

E a c h d a y w a s i n t e n d e d f o r t h e w o r s h i p

o f a d i f f e re n t h e a v e n l y b o d y . O t h e r p e o

p l e l a t e r d e d i c a t e d t h e d a y s t o o t h e r

g o d s , a n d a l t h o u g h t h e i r r e l i g i o u s s ig n if ic a n c e i s g o n e , t h e a n c i e n t n a m e s o f t h e

d a y s a r e n o t l o s t . T h e y h a v e p a s s e d

t h r o u g h m a n y l a n g u a g e s a n d a r e re

t a i n e d i n m o d e r n E n g l i s h .

T h e a s t r o n o m e r - p r i e s t s s o o n d i s c o v e r e d

t h a t t h e i r 1 2W h y d o w e h a v e . ,. 0 rr ,

_ m o n t h y e a r o f 3 6 0l e a p y e a r s ? J

d a y s w a s t o os h o r t . T h e e r r o r o f a p p r o x i m a t e l y 5

d a y s p e r y e a r a c c u m u l a t e d q u i c k l y : i n

t h e b r i e f t i m e o f 6 y e a r s a f u l l m o n t h o f

3 0 d a y s w a s l o s t . T h e y p a r t i a l l y o v e r

c a m e t h i s d e f i c i e n c y b y a d d i n g a t h i r

t e e n t h m o n t h t o t h e s i x t h y e a r . T h e

c o r r e c t e d c a l e n d a r n o w c o n t a i n e d 5

c o n s e c u t i v e 1 2 m o n t h y e a r s f o l l o w e d b y

1 y e a r w i t h 13 m o n t h s . T h i s w a s t h e

first c a l e n d a r t o i n t r o d u c e t h e leap year.

A l e a p y e a r i s a n y y e a r w h i c h h a s a n

e x t r a d a y o r d a y s a d d e d t o i t i n o r d e r

t o c o m p e n s a t e f o r s h o r t a g e s i n t h e c a l

e n d a r .

I t i s a l s o t h e y e a r w h e n t h e l a d i e s

t r a d i t i o n a l l y a b a n d o n t h e i r g e n t l e m a n

n e r a n d c h e e r f u l l y c h a s e a f t e r e l i g i b l e

g e n t l e m e n w i t h p r o p o s a l s o f m a r r i a g e .

T o d a y l e a p - y e a r h u s b a n d s a r e h u m o r

o u s l y r e g a r d e d a s v i c t i m s o f u n o f f i c ia l

c u s t o m , b u t t h e r u l e s f o r c a t c h i n g a

b a c h e l o r w i t h t h e h e l p o f t h e c a l e n d a r

w e r e o n c e w r i t t e n i n t o t h e l a w s o f s o m e

c o u n t r i e s .

O n e of t h e e a r l i e s t o f t h e s e l a w s ,

w h i c h m a n y h i s t o r i a n s b e l i e v e i s a n

a m u s i n g m y t h , w a s s u p p o s e d t o h a v e

b e e n e n a c t e d i n S c o t l a n d i n 1 2 8 8 : " I t

i s s t a t e d a n d o r d a i n e d t h a t d u r i n g t h e

r e i n ( r u l e ) o f h i s m o s t b l e s s e d M a j e s t y ,

f o r e v e r y y e a r e k n o w n a s l e p e y e a r e ,

e v e r y m a i d e n l a d y e o f b o t h h i g h a n d

l o w r a n k s h a l l h a v e l i b e r t y t o p r o p o s e

t o t h e m a n s h e l i k e s , s h o u l d h e r e f u s e

t o t a k e h e r t o b e h i s l a w f u l w y f e , h e

1 0


13/52

The chase is on: leapyear 1288 in Scotland,legally sanctioned.

s h a l l b e fined f o r t h e s u m of o n e p o u n d

o r l e s s, b e f i t t i n g h i s r a n k ; e x c e p t a n d

a l w a y s if h e c a n m a k e i t a p p e a r e t h a t h e

is b e t r o t h e d t o a n o t h e r w o m a n h e t h e n

s h a l l b e f r e e . "

I n E g y p t , t h e p r i e s t s w e r e a l s o g i f t e d a st r o n o m e r s . I t

W h y d id E g y p t ^ ^ t Qignore the leap year?

e s t a b l i s h t h e

e x a c t d a t e o f t h e first E g y p t i a n c a l e n d a r ,

b u t s o m e h i s t o r i a n s a g r e e t h a t i t w a s

4 2 4 1 B . C . T h i s d a t e i s s o m e t i m e s c a l l e d

t h e o l d e s t r e c o r d e d y e a r i n h i s t o r y .

S t a r t i n g w i t h a 1 2 m o n t h y e a r o f 3 6 0

d a y s , t h e E g y p t i a n s e v e n t u a l l y l e a r n e d

t h a t t h e y n e e d e d m o r e d a y s t o c o m p l e t e

t h e y e a r . F i v e f e a s t d a y s w e r e a d d e d t o

t h e e n d of t h e y e a r ; h o w e v e r , t h e n e w

Houses of worship in Egypt were used not only forreligious purposes. They were also used as observatories for the sun and stars. At Karnak, for instance,the temple had a row of columns pointing to the risingsun at midsummer's day. Only once in 365 days didthe sun's rays shine straight along that line.

11


14/52

The Egyptian pyramids or tombs, shown on page 13,were used at the same time by the priests for sighting Istars. Priests pinpointed the position of certain stars {'in relation to a fixed object.

Above, Sirius the Dog Star in the constellation of the Greater Dog.

W T t l e

LI .;

- i o w a s i r r e g u l a rby Roman o ff i c i a l s?

a n d c o n f u s i n g .

M o n t h s w e r e s h o r t e n e d o r l e n g t h e n e d

f o r p o l i t i c a l p u r p o s e s , s o t h a t o f fi c ia l s

c o u l d v a r y t h e i r t e r m s o f o f f ic e t o a c

c o m m o d a t e f a v o r a b l e s c h e m e s . T h e

c a l e n d a r w a s c h a n g e d s o m a n y t i m e s

An old Roman stone calendar-almanac of the first century A.D.had three months on each of itsfour sides. The front slab carriesinformation and advice coveringthe months of January, Februaryand March.

a n d h a d f a l l e n s o f a r b e h i n d , t h a t i t

b e c a m e i m p o s s i b l e t o p l a n t h e d e t a i l so f c i v i l a d m i n i s t r a t i o n o r t r a d e .

R e f o r m w a s n e c e s s a r y a n d C a e s a r

t u r n e d t o t h e G r e e k a s t r o n o m e r S o s i ge -

n e s f o r a d v i c e . T h e t w o m e n d e c i d e d

t o r e p l a c e t h e o l d R o m a n c a l e n d a r w i t h

MEVSISM\R1 VSDt& \V\I

Ml\\Dtu not. xtiM< VHORXtf

. 'ANVAR. | TEBKAR*rt,S V*


16/52

The calendar invented by Julius Caesar and Sosigenes wasused by the Western world from 5 B.C. until 1582 A.D.

a n a l t e r e d v e r s i o n of t h e s o l a r c a l e n d a r

o f t h e E g y p t i a n s .T h e 5 a d d i t i o n a l d a y s p l a c e d a t t h e

e n d o f t h e E g y p t i a n y e a r w e r e a b o l

i s h e d , a n d e a c h y e a r w a s a s s i g n e d 3 6 5

c a l e n d a r d a y s . B u t a s t h e a c t u a l l e n g t h

o f t h e y e a r w a s a p p r o x i m a t e l y o n e

q u a r t e r d a y l o n g e r t h a n 3 6 5 d a y s ,

C a e s a r d e c r e e d t h a t e v e r y f o u r t h y e a r

s h o u l d b e a l e a p y e a r o f 3 6 6 d a y s . T h e

e x t r a d a y o f t h e l e a p y e a r w a s a d d e dt o t h e s h o r t e s t m o n t h , F e b r u a r y .

T h e J u l i a n c a l e n d a r , n a m e d a f t e r J u l i u s

C a e s a r , w a sW h a t w a s w r o n g w i t h ,.. . ,. - . . 0 i n a u g u r a t e dthe Ju l i an Ca lenda r?

J a n u a r y 1 ,

4 5 B . C . A l t h o u g h i t w a s a b o l d a n d

s u c c e s s f u l c a l e n d a r t h a t w a s s u p e r i o r

t o i t s p r e d e c e s s o r s , a n e r r o r w a s r e

v e a l e d c e n t u r i e s l a t e r . T h e t r u e s o l a r

y e a r m e a s u r e s 3 6 5 d a y s , 5 h o u r s , 4 8

m i n u t e s a n d 4 6 s e c o n d s , a figure t h a t

i s 1 1 m i n u t e s a n d 1 4 s e c o n d s l e s s t h a n

t h e 3 6 5 V \ d a y s u s e d b y C a e s a r a n d

S o s i g e n e s . B e c a u s e t h e R o m a n y e a r

w a s s l i g h t l y l o n g e r t h a n t h e s o l a r y e a r ,

t h e p r a c t i c e o f a d d i n g a d a y t o t h e

f o u r t h y e a r i n t r o d u c e d a n e r r o r o f

a b o u t 3 d a y s e v e r y 4 0 0 y e a r s .

I n a n c i e n t R o m e a l l m o n t h s e x c e p t

F e b r u a r y h a d e i t h e r 2 9 o r 3 1 d a y s

b e c a u s e o d d n u m b e r s w e r e c o n s i d e r e d

l u c k y . T h e e n d o f t h e y e a r w a s t h o u g h t

t o b e u n l u c k y , a n d F e b r u a r y w a s m a d e

t h e s h o r t e s t m o n t h a n d g i v e n a n e v e n

2 8 d a y s . T h i s t r a d i t i o n p a r t l y i n f l u e n c e d

t h e sc ien t i f i c r e f o r m o f C a e s a r . H e

a s s i g n e d 3 1 d a y s t o s e v e n o f t h e m o n t h s ;

3 0 d a y s , a n u n l u c k y e v e n n u m b e r , t o

f o u r o f t h e m o n t h s ; a n d r e t a i n e d t h e

s h o r t l e n g t h of 2 8 d a y s f o r F e b r u a r y .

T h e n a m e s of t h e m o n t h s t h a t w e u s e

t o d a y a r e d e r i v e d f r o m t h e a n c i e n t

R o m a n n a m e s .

1 4


17/52

THE MONTHS OF THE YEAR

JA N U A R Y F r o m t h e d o u b l e - f a c e d

( 3 1 d a y s ) R o m a n g o d Janus, w h o s et w o f a c e s l o o k e d i n t o b o t h

t h e p a s t a n d f u t u r e . H e

i n f l u e n c e d t h e b e g i n n i n g s

o f a l l u n d e r t a k i n g s a n d

w a s h o n o r e d b y r e c e i v i n g

t h e n a m e o f t h e f ir s t m o n t h

o f t h e y e a r .

F EB RU A RY F r o m Februa a R o m a n

( 2 8 o r 2 9 f e s t i v a l o f p u r i f i c a t i o n ,

d a y s ) h e l d o n F e b r u a r y 1 5 .

M A R C H F r o m Mars t h e R o m a n

( 3 1 d a y s ) g o d o f w a r . T h e A n g l o -

S a x o n s c a l l e d M a r c h t h e

" l e n g t h e n i n g m o n t h " b ec a u s e t h e d a y s g r o w l o n g e r .

APRIL E x a c t d e r i v a t i o n i s u n c e r -

( 3 0 d a y s ) t a i n . A p r i l m a y h a v e c o m e

f r o m t h e L a t i n v e r b " t o

o p e n , " aperire a r e f e r e n c e

t o t h e s p r o u t i n g o r o p e n

i n g o f v e g e t a t i o n i n t h e

s p r i n g .

M AY F r o m Maia t h e R o m a n

( 3 1 d a y s ) g o d d e s s o f g r o w t h .

J U N E E x a c t d e r i v a t i o n i s u n c e r -

( 3 0 d a y s ) t a i n . O n e p o s s i b i l i t y i s t h a t

J u n e w a s n a m e d fo r Juno

t h e R o m a n g o d d e s s w h o

w a s q u e e n o f h e a v e n ; i t

a l s o c o u l d h a v e c o m e f r o m

t h e n a m e Junius.

9

J U LY N a m e d f o r J u l i u s C a e s a r ,

( 3 1 d a y s ) w h o w a s b o r n i n t h e m o n t ho f J u l y.

A UG UST N a m e d f o r t h e R o m a n e m -

( 3 1 d a y s ) p e r o r O c t a v i u s A u g u s t u s

b e c a u s e o f h i s m a n y v i c

t o r i e s i n t h i s m o n t h .

S E PT E M B ER F r o m t h e L a t i n septem,

( 3 0 d a y s ) m e a n i n g s e v e n . I n t h e o l d

R o m a n c a l e n d a r , S e p t e m

b e r w a s t h e s e v e n t h m o n t h .

T h e S w i s s c a l l S e p t e m b e r

Herbstmonat t h e m o n t h

o f h a r v e s t .

it*' is:

OCTOBER

( 3 1 d a y s )

ftJ )

JZ^,

N O V E M B E R

( 3 0 d a y s )

D E C E M B E R

( 3 1 d a y s )

F r o m t h e L a t i n octo

m e a n i n g e i g h t . T h e S l a v s

c a l l e d O c t o b e r t h e " y e l l o w

m o n t h " t o d e s c r i b e t h e

t i m e o f y e a r w h e n l e a v e s

t u r n y e l l o w.

F r o m t h e L a t i n novem,

m e a n i n g n i n e . T h e " w i n d

m o n t h " a n d t h e " b l o o d

m o n t h " w e r e A n g l o - S a x o n

n a m e s f o r N o v e m b e r .

F r o m t h e L a t i n decern

m e a n i n g t e n . Heligh-

monath ( h o l y m o n t h ) i s

a n o l d S a x o n n a m e f o r

D e c e m b e r , t h e m o n t h o f

C h r i s t m a s .

1 5


18/52

C a e s a r l e f t a v a l u a b l e b e q u e s t t o

c a l e n d a r s c i e n c e , b u t h i s c a l e n d a r c o u l d

n o t o u t l i v e i t s e r r o r s . A c h a n g e w a s

n e e d e d . T h i s t i m e i t w a s a r e l i g i o u s

g r o u p t h a t p r o d u c e d t h e n e x t g r e a t

c a l e n d a r r e f o r m .

C a t h o l i c o f fi c ia l s w e r e d i s t u r b e d t o find

tha t the er-How d id a wand e r ing r o r i n t h eholiday' give us our , ,. ,

' , . - J u l i a n calen-present calendar?

d a r w o u l d

u l t i m a t e l y c a u s e E a s t e r t o a r r i v e i n t h e

w i n t e r . E a s t e r is t r a d i t i o n a l l y c e l e b r a t e d

i n t h e s p r i n g , a n d r e l i g i o u s l e a d e r sw a n t e d t o p e r p e t u a t e t h e t r a d i t i o n .

F o r h u n d r e d s o f y e a r s u n s u c c e s s f u l

a p p e a l s f o r a n e w c a l e n d a r h a d b e e n

m a d e t o r u l e r s a n d p o p e s . F i n a l l y P o p e

G r e g o r y X I I I d e c i d e d t o g i v e h i s a t t e n

t i o n t o t h e p r o b l e m o f t h e d a t e o f E a s t e r .

I n t h e y e a r 1 5 8 2 A . D . , G r e g o r y , a s s i s t e d

b y a c o u n c i l o f s c i e n t i s t s , s t a b i l i z e d t h e

c a l e n d a r t o w i t h i n 2 6 s e c o n d s o f t h es o l a r y e a r a l o s s o f o n l y o n e d a y i n

3 , 3 2 3 y e a r s .

T h i s a c c u r a c y w a s a c h i e v e d w i t h a

n e w l e a p y e a r r u l e t h a t a f f e c t s t h e c e n

t u r y y e a r s . C e n t u r y y e a r s a r e t h o s e

y e a r s t h a t e n d w i t h a d o u b l e z e r o , f o r

e x a m p l e , 1 8 0 0 a n d 1 9 0 0 . T h e P o p e a n d

h i s c o u n c i l o r d e r e d t h a t n o c e n t u r y y e a r

c o u l d b e a l e a p y e a r u n l e s s i t w a s

d i v i s i b le b y 4 0 0 . T h u s 1 6 0 0 , 2 0 0 0 a n d

2 4 0 0 a r e l e a p y e a r s , b u t 1 7 0 0 , 1 8 0 0 a n d

1 9 0 0 a r e r e g u l a r y e a r s . A l l o t h e r y e a r s

a d h e r e t o t h e f o u r y e a r r u l e ( o n e 3 6 6

d a y e v e r y f o u r y e a r s ) o f t h e J u l i a n

c a l e n d a r . T h e o m i s s i o n o f 3 l e a p y e a r

d a y s o u t o f e v e r y 4 0 0 y e a r s w a s t h e

s i m p l e f o r m u l a t h a t r e t i r e d t h e J u l i a n

c a l e n d a r .

T h e G r e g o r i a n c a l e n d a r , w h i c h w e u s e

t oday, wasW as Gregory's calendar . , ,accepted by the world? 4 ^

s t a l l e d i n

S p a i n , P o r t u g a l , F r a n c e , p a r t s of

I t a l y a n d t h e C a t h o l i c s t a t e s o f G e rm a n y . T h e P r o t e s t a n t c o u n t r i e s o f S w e

d e n a n d D e n m a r k a n d t h e P r o t e s t a n t

s t a t e s o f G e r m a n y a c c e p t e d t h e G r e g o

r i a n c a l e n d a r i n 1 7 0 0 . G r e a t B r i t a i n

a n d t h e A m e r i c a n C o l o n i e s m a d e t h e

c h a n g e i n 1 7 5 2 , J a p a n i n 1 8 7 3 a n d

C h i n a in 1 9 1 2 . R u s s i a a d o p t e d t h e

G r e g o r i a n c a l e n d a r i n 1 9 1 8 b u t l a t e r

a b a n d o n e d i t t o e x p e r i m e n t w i t h s o m e

o r i g i n a l c a l e n d a r s . F i v e a n d s i x d a y

w e e k s w e r e t r i e d b u t t h e s e w e r e n o t t o o

s u c c e s s f u l , a n d i n 1 9 4 0 R u s s i a r e t u r n e d

t o t h e G r e g o r i a n s y s t e m .

T h e c a l e n d a r t h a t G r e g o r y m o d i f i e d

a n d p a s s e d o n t o u s r e s e m b l e s a h i s t o r y

b o o k w i t h p a g e s t h a t m i x n a r r a t i v e s o f

s c i e n c e , r e l i g i o n , p a g a n l e g e n d s a n d t h e

p r i v a t e p o l i t i c s o f a n c i e n t c i v i l i z a t i o n s .

A l t h o u g h s o m e o f t h e h i s t o r y o f t i m e

m e a s u r e m e n t is t o o o l d a n d d i m t o b e

r e a d e a s i l y , t w o c o n t r i b u t i o n s s t a n d

o u t a s t h e c l e a r e s t i n f l u e n c e s o n o u r

c a l e n d a r .

T h e f ir s t o f t h e s e w a s t h e i n s p i r e d

s o l a r c a l e n d a r s o f t h e B a b y l o n i a n s a n d

E g y p t i a n s . T h e i r s w a s p e r h a p s t h e

g r e a t e s t a c h i e v e m e n t o f c a l e n d a r s ci

e n c e , f o r i t c r e a t e d a d e p e n d a b l e s y s t e m

o f t i m e m e a s u r e m e n t t h a t r e g u l a t e d

h u m a n a c t i v i t i e s t o t h e s e a s o n s .

O u r s e c o n d d i r e c t l i n k b e t w e e n t h e c a le n d a r a n d t h e

W h y d o w eobserve a Sabbath? P f t gives us one

o f t h e p a t t e r n s

o f m o d e r n l i fe t h e w e e k l y o b s e r v a n c e

1 6


19/52

The French Revolutionswept away many oldtraditions. The calendarwas discarded alongwith Sundays, royalty

and religious festivals.The new calendar haddifferent names for themonths and the days,and started with 1792to commemorate theyear of French liberty.After a few years, however, the internationalGregorian Calendarwas restored:

* % r >

The longest night inAmerican history oc-cured on September 2,1 7 5 2 . D u r i n g t h echange-over from theJulian to the GregorianC a l e n d a r, 1 1 dayswere lost. Americanswho went to bed on thenight of Sept. 2 wokeup on the morning ofSeptember 14.

The Julian Calendar isstill used by the Greekand Russian Churches.People of these faithscelebrate Christmas

after the Catholic andProtestant festivals.


20/52

The ruins of the observatory ofChichen Itza in Yucatan, Mexico,once the center of the secondMayan empire.

The Mayans, had a suncalendar, and used

spec i a l numera l sshaped l ike humanfaces for their recordsof dates. These werecarved on stone coTumns called steles.

o f a S a b b a t h . H i s t o r i c a l l y t h i s i s t h e

d e d i c a t i o n , w h i c h w e s t i l l o b s e r v e , o f

t h e s e v e n t h d a y o f t h e w e e k f o r r e s t

a n d w o r s h i p . S a b b a t h c o m e s f r o m t h e

H e b r e w shabbat m e a n i n g a d a y o f

r e s t . T h e J e w s p e r p e t u a t e d th i s c u s t o m

i n o r d e r t o d e v e l o p a b e t t e r w a y of l i f e

r a t h e r t h a n f o r s c i e n t i f ic r e a s o n s .

T h e t r a d i t i o n o f t h e S a b b a t h w a s n o t

f o r m a l l y b l e s s e d u n t i l t h e p r o c l a m a t i o n

o f t h e h o l i n e s s o f t h e s e v e n t h d a y i n t h e

T e n C o m m a n d m e n t s .

T h e a n c i e n t J e w i s h c a l e n d a r , i n w h i c h

t h e d a y b e g i n s a t s u n s e t , is u s e d b y t h e

g o v e r n m e n t o f I s r a e l a n d b y J e w s e v e r y

w h e r e f o r r e l i g i o u s p u r p o s e s . M o n t h s

a r e c a l c u l a t e d b y t h e m o o n , a n d t h e

s u n d e t e r m i n e s t h e y e a r . T h e f irst y e a r

i s r e c k o n e d f r o m t h e t r a d i t i o n a l C r e a

t i o n , 3 7 6 1 B . C . , a n d t h e N e w Y e a

g e n e r a l l y a r r i v e s i n S e p t e m b e r . Va r y

i n g f r o m 3 5 3 t o 3 8 5 d a y s , t h e J e w i s h

y e a r c o n t a i n s 1 2 m o n t h s o f 2 9 t o 3 0

d a y s e a c h a n d i s k e p t u p t o d a t e b y

i n s e r t i n g a 13 t h m o n t h 7 t i m e s d u r i n g

e v e r y 19 y e a r p e r i o d .

W hy is the MoslemCalendar confusing?

T h e M o s l e m c a l e n d a r i s e v e n m o r e c o n

f u s i n g t h a n t h e

J e w i s h . " T w e l v e

m o n t h s i s t h e

n u m b e r o f m o n t h s o r d a i n e d b y G o d

a c c o r d i n g t o G o d , " i s t h e v e r s e of t h e

K o r a n t h a t e s t a b l i s h e d t h e M o s l e m ca l -

1 8


21/52

e n d a r . T h e s e w o r d s w e r e t a k e n f r o m a

p r o c l a m a t i o n o f M o h a m m e d , a n d h i s

f o l lo w e r s a n a l y z e d t h e P r o p h e t ' s i n t e n t

i n a s t r i c t m a n n e r .

T h e y c r e a t e d a c o m p l e t e l y l u n a r c a l

e n d a r t h a t i g n o r e s t h e s u n a n d a l l o w s

t h e m o n t h s t o w a n d e r w i t h o u t r e g a r d

t o t h e s e a s o n s . F o r e x a m p l e , o n e y e a r

t h e m o n t h o f Rajah m a y b e a w i n t e r

m o n t h , b u t s e v e r a l y e a r s l a t e r i t w i l l

a p p e a r i n t h e s u m m e r . F o r t r a d e o r

i n t e r n a t i o n a l e x c h a n g e , h o w e v e r , M o s

l e m s n o w u s e t h e G r e g o r i a n c a l e n d a r ,

a n d m a n y o f t h e i r n e w s p a p e r s a r e

d o u b l e - d a t e d .

How are some OrientalCalendars arranged?

T h e C h i n e s e a l s o l i v e w i t h t w o c a l e n -

d a r s : t h e

Hsi-li, o r

G r e g o r i a n

C a l e n d a r , a n d t h e a n c i e n t ( 2 3 9 7 B . C . )

C h i n e s e c a l e n d a r i n w h i c h d a t e s a r e

g i v e n b y n a m i n g t h e d a y , t h e m o o n a n d

t h e y e a r . T h e d a y s a r e g r o u p e d i n t o

c y c l e s o f 6 0 , s i m i l a r t o o u r w e e k t h a t

u s e s a c y c l e o f 7 d a y s .

I n I n d i a t h e r e a r e c l o s e t o t h i r t y d i f

f e r e n t c a l e n d a r s , s o m e o f w h i c h a r e

b a s e d o n t h e s u n a n d t h e m o o n , w h i l e

o t h e r s r e l y o n r e l i g i o u s d o c t r i n e s a n d

a s t r o l o g y . T h e m u d d l e c a u s e d b y t h e

h o d g e p o d g e of c o m p e t i n g c a l e n d a r s h a s

s t i r r e d m a n y I n d i a n l e a d e r s t o w o r k f o r

a s i m p l e r s y s t e m . S i n c e 1 9 5 7 t h e g o v

e r n m e n t h a s o ff ic ia ll y r e c o m m e n d e d

t h a t o n l y t w o c a l e n d a r s b e u s e d t h e

G r e g o r i a n a n d a n e w n a t i o n a l c a l e n d a r .

>r- si A.4>


22/52

v a n c e d s c i e n c e , w e r e a b l e t o d e v e l o p a

r e m a r k a b l e c a l e n d a r o f 3 6 5 . 2 4 d a y s .

T h e M a y a n y e a r o f 3 6 5 d a y s w a s

d i v i d e d i n t o 18 m o n t h s o f 2 0 d a y s e a c h ,

t o w h i c h w e r e a d d e d 5 d a y s . T h e y u s e d

a p e r i o d o f 5 2 y e a r s f o r a l a r g e r u n i t

o f t i m e t h a t w a s c o m p a r a b l e t o o u r

c e n t u r y . C o r r e c t i o n s w e r e i n t r o d u c e d

a s r e q u i r e d , a n d d e s p i t e t h e c u m b e r

s o m e s y s t e m o f n u m b e r s , t h e s y m m e t r y

a n d o r d e r of t h e c a l e n d a r w e r e m a i n

t a i n e d .

N o t m u c h i s k n o w n a b o u t t h e M a y a n

s y s t e m of a s t r o n o m y . B u t f o r i t s t i m e

i t m u s t h a v e b e e n s u p e r l a t i v e ; t h e s e

p e o p l e a c c u r a t e l y d e t e r m i n e d t h e o r b i t

o f V e n u s w h o w a s w o r s h i p p e d a s t h e i r

m o s t i m p o r t a n t g o d , a f t e r t h e s u n .

Would you prefer theWorld Calendar?

M a n y i m p r o v e m e n t s h a v e b e e n su g

g e s t e d t o e l i m

i n a t e t h e i n

c o n s i s t e n c i e s

t h a t st i ll e x i s t i n o u r p r e s e n t G r e g o r i a n

c a l e n d a r . F r o m o n e y e a r t o t h e n e x t ,

n e w c a l e n d a r s h a v e t o b e p r i n t e d . N a

t i o n a l e v e n t s , h o l i d a y s , b i r t h d a y s , r e n t

a n d i n s u r a n c e p a y m e n t s , p a y d a y s a n d

a l l o f t h e b u s i n e s s a n d r e c r e a t i o n o f o u r

l i v e l y s o c i e t y n e v e r f a l l o n t h e s a m e d a y .

O n e r e f o r m , c a l l e d t h e W o r l d C a l e n d a r ,

u s e s t h e s a m e c a l e n d a r e v e r y y e a r a n d i s

d e s i g n e d w i t h s i m p l i c i t y a n d a r i t h m e t i

c a l p r e c i s i o n . T h e y e a r i s d i v i d e d i n t o 4

e q u a l q u a r t e r s o f 1 3 w e e k s e a c h a n de a c h q u a r t e r b e g i n s o n a S u n d a y a n d

e n d s o n a S a t u r d a y . T h e r e a r e 3 6 4 n u m

b e r e d d a y s i n t h e y e a r , a n d e v e r y m o n t h

The suggested W orld Calendar with four equal quarters of 13 weeks. W is Worldsday, a world holidaywhich follows December 30 every year. L, anotherworld holiday, is Leap Year Day and follows June 30in leap years.

2 0

h a s 2 6 w e e k d a y s i n s t e a d of t h e 2 4 t o 2 7

t h a t w e n o w h a v e .

T h e 3 6 5 t h d a y , p l a c e d a f t e r D e c e m

b e r 3 0 , i s c a l l e d W o r l d s d a y a n d i s

i n t e n d e d a s a n i n t e r n a t i o n a l h o l i d a y t o

a f fi r m t h e b o n d t h a t e x i s t s b e t w e e n a l l

p e o p l e . I n l e a p y e a r s , t h e e x t r a d a y is

a d d e d t o t h e e n d o f J u n e .

A t t h e b e g i n n i n g o f t h e n e w y e a r t h e

e x a c t c y c l e i s r e p e a t e d , a n d c o r r e s p o n d

i n g d a t e s o c c u r o n t h e s a m e d a y e v e r y

y e a r . T o i l l u s t r a t e : J u n e 3 , w h e t h e r t h e

y e a r i s 1 9 6 5 , 1 9 8 7 o r a n y y e a r s e l e c t e d

a t r a n d o m , w i l l a l w a y s b e a S u n d a y .

E v e r y y e a r , C h r i s t m a s , D e c e m b e r 2 5 ,

w o u l d f a ll o n a M o n d a y a n d a l l o w a

l o n g w e e k e n d .

A n u m b e r o f w o r l d l e a d e r s a n d s c ie n

t i s t s h a v e e n d o r s e d t h e W o r l d C a l e n d a r

a s a s t a b l e s y s t e m o f t i m e m e a s u r e m e n t .

B u t l i k e m a n y o t h e r w o r t h w h i l e r e

f o r m s , b e f o r e t h e W o r l d C a l e n d a r c a n

b e u n i v e r s a l l y a d o p t e d , i t w i l l h a v e t o

o v e r c o m e t r a d i t i o n a n d p r e j u d i c e .

JANUARYS M T W T F S1 2 3 4 5 6 78 9 10 11 12 13 1415 16 17 18 19 20 2122 23 24 25 26 27 2829 30 31

FEBRUARYS M T W T F S

1 2 3 45 6 7 8 9 10 1112 13 14 15 16 17 1819 20 21 22 23 24 2526 27 28 29 30

MARCHS M T W T

3 4 5 6 7 10 11 12 13 1417 18 19 20 2124 25 26 27 28

APRILS M T W T F S1 2 3 4 5 6 78 9 10 11 12 13 1415 16 17 18 19 20 2122 23 24 25 26 27 2829 30 31

MAYS M T W T F S

1 2 3 45 6 7 8 9 10 1112 13 14 15 16 17 1819 20 21 22 23 24 2526 27 28 29 30

JUNES M T W T

3 4 5 6 7 10 11 12 13 1417 18 19 20 2124 25 26 27 28

JULYS M T W T F S1 2 3 4 5 6 78 9 10 11 12 13 1415 16 17 18 19 20 2122 23 24 25 26 27 2829 30 31

AUGUSTS M T W T F S

1 2 3 45 6 7 8 9 10 1112 13 14 15 16 17 1819 20 21 22 23 24 2526 27 28 29 30

SEPTEMBS M T W T

3 4 5 6 7 10 11 12 13 117 18 19 20 2124 25 26 27 28

OCTOBERS M T W T F S1 2 3 4 5 6 78 9 10 11 12 13 1415 16 17 18 19 20 2122 23 24 25 26 27 2829 30 31

NOVEMBERS M T W T F S

1 2 3 45 6 7 8 9 10 1112 13 14 15 16 17 1819 20 21 22 23 24 2526 27 28 29 30

DECEMBS M T W T

3 4 5 6 7 10 11 12 13 1417 18 19 20 2124 25 26 27 28


23/52

Father Time a wellknown figure aroundDecember 31, once wasthe honored Roman godSaturn. His representation today with a scythecomes from the confusion of Saturn with theGreek god of the harvest, Cronos, who wasdepicted with a sickle.Cronos was thought tobe the Greek equivalentof the Roman Saturn.

T i m e i n t h e S o l a r S y s t e m

S c i e n t i f ic t i m e k e e p i n g i s b a s e d o n o u r k n o w l e d g e o f h o w t h e e a r t h , t h e

s u n a n d d i s t a n t s t a r s m o v e i n r e l a t i o n t o e a c h o t h e r .

I n t h e p a s t t h e c a l e n d a r a n d t h e c l o c k h a v e m o r e o r l e ss c o r r e s p o n d e d t o

t h i s m o t i o n t o g i v e u s a r o u g h b a s i s f o r m e a s u r i n g t i m e . B u t s c i e n t i s t s t o d a y

m u s t h a v e f a r m o r e a c c u r a t e k n o w l e d g e of t h e m o t i o n of t h e h e a v e n s . A d v a n c e s

i n p h y s i c s , c h e m i s t r y , b i o l o g y a n d m a t h e m a t i c s h a v e m a d e i t n e c e s s a r y t o

m e a s u r e t i m e w i t h g r e a t p r e c i s i o n .

T o a c h i e v e t h i s p r e c i s i o n , a s t r o n o m e r s u s e t h e s o l a r s y s t e m a n d t h e u n i v e r s e

a s a g i a n t t i m e k e e p e r , w h i l e t h e y i m p r o v e a n d r e f in e t h e i r o b s e r v a t i o n s . T h e

m e a s u r e m e n t o f t i m e h a s b e c o m e a s c i e n c e t h a t s e r v e s a l l o t h e r s c i e n c e s .

W h e n w e l o o k a t t h e c a l e n d a r t o find

o u t t h e d a t e , w e a r e ,H o w f a r d o e s m a s e n s e ? c h e c k i n gthe earth rotate , .,

. _ a s k y m a p t h a t r ei n o n e h o u r ? J r

v e a l s t h e e x a c t p o s i

t i o n of t h e e a r t h i n i t s o r b i t a r o u n d t h e

s u n . A n d a s t h e e a r t h r o t a t e s o n i t s a x i s ,w e k n o w t h a t t h e h o u r h a n d o f t h e c l o c k

w i l l m o v e t w i c e a s f a s t . F o r e v e r y 1 5

o f r o t a t i o n t h e c l o c k a d v a n c e s o n e h o u r .

A f t e r t h e e a r t h h a s r o t a t e d 3 6 0 , t h e

h o u r h a n d h a s t u r n e d t w o f u ll c i r c l e s

a n d t h e d a y i s c o m p l e t e d .

T h e i n t e r v a l of t i m e n e c e s s a r y f o r t h e

e a r t h t o t r a v e l a r o u n d t h e s u n i s d e f i n e d

a s a y e a r o r , m o r e s c i e n t i f i c a l l y, a s a

solar year. I t i s 3 6 5 d a y s , 5 h o u r s , 4 8

While the earth makesone full turn on its axis,the hour hand of theclock has to turn twicearound the dial; forevery 15 of rotationthe clock advances onehour.


24/52

m i n u t e s a n d 4 6 s e c o n d s l o n g . B e c a u s e

t h e e a r t h i s i n c o n t i n u o u s m o t i o n , w e

find i t c o n v e n i e n t t o m e a s u r e t h e s t a r t

a n d fin ish o f a s i n g l e s o l a r y e a r f r o m

o n e v e r n a l e q u i n o x t o t h e n e x t v e r n a l

e q u i n o x ( s e e F i g u r e 3 o n p a g e 2 4 ) .

A s t h e e a r t h c o n t i n u e s i n i t s o r b i t , i t

c r e a t e s o n e o f t h eW h e n d o t h e g r e a t l e s o f n a _sun's rays slant , . , ... ' t u r e in w h i c h t h ethe most?t h e l e a s t ? * o u r s e a s o n s f o l l o w

e a c h o t h e r i n a s e

q u e n c e t h a t is r e p e a t e d e v e r y y e a r . I f

t h e e a r t h s t o o d s t il l i n s t e a d o f p u r s u i n gi ts p a t h a r o u n d t h e s u n , t h e c l i m a t e i n

a n y s p e c if i c l o c a t i o n w o u l d a l w a y s b e

t h e s a m e . T h e c l i m a t e a n d t h e s e a s o n s

v a r y b e c a u s e t h e c o n s t a n t m o t i o n o f

t h e e a r t h c h a n g e s t h e a n g l e o f s u n l i g h t .

A d e s c r i p t i o n o f h o w t h e a n g l e o f s u n

l i g h t a f f e c t s t h e s e a s o n s i s g i v e n i n

F i g u r e 6 o n p a g e 2 5 .

Where does a yearequal a day?

O n o t h e r p l a n e t s , t h e s e a s o n s a n d u n i t s

o f t i m e v a r y

g r e a t l y f r o m

t h o s e w e k n o w

o n e a r t h . A n i n h a b i t a n t o f t h e r i n g e d

p l a n e t S a t u r n w o u l d l i v e w i t h a d a y

t h a t i s 1 0 h o u r s a n d 1 2 m i n u t e s o f o u r

t i m e a n d a y e a r t h a t e q u a l s 29Vi o f

o u r y e a r s . T h r o u g h t h e t e l e s c o p e w eo b s e r v e t h a t t h e p l a n e t V e n u s t a k e s IVi

m o n t h s t o j o u r n e y a r o u n d t h e s u n ,

w h i l e t h e p l a n e t M a r s m a k e s t h e t r i p i n

6 8 7 d a y s a n d h a s s e a s o n s a b o u t d o u b l e

t h e l e n g t h o f t h e e a r t h ' s .

A N e p t u n i a n y e a r e q u a l s 1 6 5 e a r t h

y e a r s , b u t a d a y o n t h i s d i s t a n t p l a n e t

l a s t s o n l y 1 5 h o u r s a n d 4 5 m i n u t e s

w h e n t i m e d b y o u r c l o c k . A c a l e n d a r

p r i n t e d f o r M e r c u r y w o u l d s h o w n o d i f

f e r e n c e b e t w e e n a y e a r a n d a d a y ,

b e c a u s e t h e p e r i o d of r o t a t i o n i s i d e n t i

c a l t o t h e p e r i o d r e q u i r e d t o c o m p l e t e

a f u l l o r b i t .

O u r s u n i s o n e o f m a n y s t a r s i n t h eu n i v e r s e . T h e r e i s s o m e e v i d e n c e t h a t ,

l i k e o u r s u n , o t h e r s ta r s h a v e p l a n e t s

r e v o l v i n g a r o u n d t h e m . T h e c a l c u l a t i o n

o f t i m e o n o n e o f t h e s e p l a n e t s w o u l d

n o t b e in a n y w a y r e l a t e d t o t h e m o v e

m e n t s o f o u r s o l a r s y s t e m . F o r a n

i n h a b i t a n t o f t h a t p l a n e t , t i m e w o u l d

d e p e n d so l e l y o n t h e s t a r ( s u n ) o f t h e

s o l a r s y s t e m i n w h i c h h e l i v e d .

What is alight year?

I f w e l o o k b e y o n d o u r o w n s o l a r s y s t e m

i n t o o t h e r a r e a s o f t h e

u n i v e r s e , t h e d i s t a n c e s

b e c o m e s o g r e a t t h a t w e

c a n n o t u s e o r d i n a r y s y s t e m s o f m e a

s u r e m e n t . W e h a v e t o d e s c r i b e t h e s e

d i s t a n c e s i n light years a s p e c i a l u n i t

o f m e a s u r e m e n t t h a t c o m b i n e s b o t h d i st a n c e a n d t i m e .

A l i g h t y e a r is t h e d i s t a n c e t h a t l i g h t

t r a v e l s i n o n e y e a r . T h e v e l o c i t y of l i g h t

i s 1 8 6 , 0 0 0 m i l e s p e r s e c o n d , a n d o n e

l i g h t y e a r i s a p p r o x i m a t e l y s ix t r i l l i o n

m i l e s .

O n e l i g h t y e a r = 1 8 6 , 0 0 0

X 6 0 ( n u m b e r of s e c o n d s i n a m i n u t e )

X 6 0 ( n u m b e r o f m i n u t e s i n a n h o u r )

X 2 4 ( n u m b e r o f h o u r s i n a d a y )

X 3 6 5 1 / ( n u m b e r o f d a y s i n a y e a r )

= 5 , 8 8 0 , 0 0 0 , 0 0 0 , 0 0 0 m i l e s

o r a p p r o x i m a t e l y s i x t r i l l i o n m i l e s .

W h e n w e s a y t h a t A l p h a C e n t a u r i ,

t h e n e a r e s t s t a r , i s 4Vs l i g h t y e a r s a w a y,

w e m e a n t h a t i ts d i s t a n c e f r o m t h e e a r t h

i s 4 V 3 X 6 t r i l l i o n , o r 2 6 t r i l l i o n m i l e s .

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B u t a l i g h t y e a r g i v e s u s i n f o r m a t i o n

a b o u t t i m e a s w e l l a s d i s t a n c e , a n d w e

c a n a l s o s t a t e t h a t l i g h t f r o m t h e s t a r

w i l l t a k e 4V6 y e a r s t o r e a c h t h e e a r t h .

L i g h t f r o m o u r o w n s t a r , t h e s u n ,

t a k e s o n l y a l i t t l e m o r e t h a n 8 m i n u t e st o r e a c h u s . T h e A n d r o m e d a G a l a x y ,

w h i c h c a n b e s e e n o n a c l e a r n i g h t w i t h

o u t a t e l e s c o p e , i s 2 m i l l i o n l i g h t y e a r s

a w a y a d i s t a n c e o f 9 b i l l i o n b i l l i o n

m i l e s .

L i k e a l l p l a n e t s i n o u r s o l a r s y s t e m , t h e

e a r t h r e v o l v e s i n i tsC a n w e r el y Q r b i t a n d r o t a t e Q non the sun tomeasure time? i t s a x i s a t t h e s a m e

t i m e . D u r i n g r o t a t i o n ,

t h e s u n c r o s s e s e a c h m e r i d i a n ( F i g

u r e 2 o n p a g e 2 4 ) e v e r y 2 4 h o u r s . T h e

t i m e t h a t e l a p s e s f r o m o n e n o o n t o t h e

n e x t , t h a t i s , t h e t i m e b e t w e e n t w o s u c

c e s s i v e c r o s s i n g s o f t h e s a m e m e r i d i a n

i s c a l l e d a n apparent solar day. A s u n

d i a l t h a t i s c a r e f u l l y d e s i g n e d w i l l t h e r ef o r e m e a s u r e t h e h o u r s a n d m i n u t e s i n

a p p a r e n t s o l a r t i m e .

T h e s u n , h o w e v e r , i s a n u n r e l i a b l e

g u i d e f o r a c c u r a t e t i m e k e e p i n g . T h e

v e l o c i t y of t h e e a r t h i n i t s o r b i t v a r i e s

t h r o u g h o u t t h e y e a r , c a u s i n g t h e a p

p a r e n t m o t i o n of t h e s u n t o a p p e a r

i r r e g u l a r . T h e w o r d " a p p a r e n t " i s u s e d

b e c a u s e w h a t s e e m s t o b e t h e m o v e

m e n t o f t h e s u n i s a c t u a l l y t h e m o v e

m e n t o f t h e e a r t h .

A p p a r e n t s o l a r d a y s r e f le c t t h e i r re g

u l a r i t y o f t h e e a r t h ' s v e l o c i t y a n d a r e

n o t e q u a l i n l e n g t h . D a y s m e a s u r e d b y

a p p a r e n t s o l a r t i m e i n J u l y a v e r a g e

1 5 s e c o n d s s h o r t e r t h a n t h e d a y s i n

J a n u a r y , a n d D e c e m b e r 2 5 i s 5 0 s e c

o n d s l o n g e r t h a n S e p t e m b e r 13.

T o p r o d u c e d a y s o f i d e n t i c a l l e n g t h , i t

w a s n e c e s s a r y t oW h y d o w e u s e c o m p r o m i s e w i t ha n i m a g i n a r y s u n . ,

. , . _ t h e s o l a r s y s t e m .f o r t i m e k e e p i n g ? J

S c i e n t i s t s c r e a t e d

a n i m a g i n a r y o r h y p o t h e t i c a l s u n w h i c h

m o v e s t h r o u g h s p a c e w i t h a m e a n , o r

a v e r a g e , v e l o c i t y of a l l t h e a c t u a l v e l o c i

t i e s t h a t t h e r e a l s u n h a s . T h e y a l s o

i g n o r e d t h e v a r i a t i o n s i n v e l o c i t y o f t h e

e a r t h a s i t r o t a t e s o n i t s a x i s a n d f o l l o w s

i t s o r b i t a r o u n d t h e s u n . I n t h i s mean

solar system t h e l e n g t h o f t h e y e a r i s

n o t c h a n g e d , b u t t h e d a y s a r e a l l a s

s i g n e d a n e q u a l l e n g t h o f 2 4 h o u r s e a c h .

M e a n s o l a r t i m e i s f r e q u e n t l y c a l l e d

local time.

W ha t is a stand ardtime zone?

T h e i m a g i n a r y s u n o f t h e m e a n s o l a r

s y s t e m t r a v e l s

f r o m t h e e a s t t o

t h e w e s t a n d

c i r c l e s t h e g l o b e i n e x a c t l y 2 4 h o u r s .

L o n g i t u d e s 1 t o t h e e a s t o f u s a r e

4 m i n u t e s a h e a d i n l o c a l t i m e , a n d t h o s e

1 t o t h e w e s t , w h e r e t h e s u n h a s n o t

y e t a r r i v e d , a r e 4 m i n u t e s b e h i n d .

T o d a y , e a c h b a n d o f l o n g i t u d e ( s e e

F i g u r e 2 o n p a g e 2 4 ) h a s i t s o w n l o c a l

t i m e . Y e a r s a g o , w h e n c l o c k s v a r i e d

f r o m t o w n t o t o w n , i t w a s d i f f ic u l t f o r

t r a v e l e r s t o m e e t t r a i n s c h e d u l e s a n d t o

m a k e a p p o i n t m e n t s e v e n s h o r t d i s t a n c e s

a w a y . I n 1 8 8 3 , t h e U n i t e d S t a t e s a n d

C a n a d i a n r a i l r o a d s a d o p t e d a s y s t e m for

s t a n d a r d t i m e .

I n 1 9 1 8 , t h e U n i t e d S t a t e s C o n g r e s s

p a s s e d a l a w e s t a b l i s h i n g t h e f o u r S t a n

d a r d T i m e Z o n e s t h a t w e u s e t o d a y i n

t h e U n i t e d S t a t e s .

A m e r i d i a n o f 15 o f l o n g i t u d e s e p a

r a t e s e a c h z o n e . T h e d i v i d i n g l i n e s ,

CONTINUED ON PAGE 26


26/52

Figure 1. HEMISPHERES OF THE EARTHThe equator is halfway between the two poles

and divides the earth into the Northern and Southern Hemispheres. The earth rotates on its axis at avelocity of approxim ately 1000 miles per hour atthe equator. It takes the earth 24 hours to turncompletely through one full rotation.

Figure 2. GREAT CIRCLES OF LONGITUDEThe meridians of longitude are imaginary circles

of equal size which pass through both poles. Greenwich, England, is on the zero meridian. To the east,meridians are numbered 15 E, 30 E, 45 E, etc.Those to the west are numbered 15 W, 30 W,45 W until 180 W, which is the same longitude as

180 E. The earth rotates 15 or the distance fromone meridian to the next in 1 hour.

*oo*

*\D' **

Figure 3. WHEN DAY EQUALS NIGHTOn or about the dates March 21 and September

23, the sun is directly above the equator, and nightand day are each 1 2 hours long everywhere in theworld. March 21 is called the vernal equinox andSeptember 23, the autumnal equinox.

Figure 4. LONG DAYS AND SHORT NIGHTS

On June 21 there are 24 hours of daylight in the

North Pole region and 24 hours of darkness at theSouth Pole. During the summer, countries in thenorthernmost parts of the Northern Hemisphere havethe longest days and shortest nights. In Stockholm,some summer days last for 19 hours while the nightsare only 5 hours long.

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PERPENDICULAR TCEARTHS ORBT ,

EARTHS ORBIT

_. SEASONAL VARIATION OF THEl-igure o. A N G L E Q F S U NL |G HTThe vertical beam's of summer sunlight are con

centrated and produce maximum heat. When thebeams slant, as in the winter (or morning and afternoon of any season), they are thinned out over agreater area and the heat is less intense.

Before the beams reach the surface of the earth,

they lose some heat to the atmosphere. In the winterthe volume of atmosphere through whicTi the slantedbeams pass is larger than in summer and thus moreheat is absorbed. During the winter this loss of heatto the atmosphere causes the surface of the earth tobe colder than it is in the summer.

WINTERDEC. 21

Figure 7. ORBIT OF THE FOUR SEASONSThe seasons are caused by the angle of the sun's

rays and the changing lengths of day and night.The Northern Hemisphere receives direct rays insummer and slanted rays in winter. In June therotating earth receives more sunlight (longer days)above the equator than it does below. The twohemispheres have opposite seasons: when it is summer in New York, it is winter in Sydney, Australia.

Figure 5. ORBIT OF THE EARTH

The earth follows the path of an ellipse as it revolves around the sun. Moving at a velocity of 18.5miles per second (666,000 miles per hour), theearth takes one year to make a full trip. As it revolves through its orbit around the sun (causing theseasons), the earth also rotates on its axis (causingnight and day).

25


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h o w e v e r , a r e n o t s t r a i g h t i n o r d e r t o

a c c o m m o d a t e s o m e s t a t e b o r d e r s a n d

r a i l r o a d t e r m i n a l s . T h e 1 5 i n t e r v a l w a s

c h o s e n b e c a u s e i t t a k e s o n e h o u r f o r

t h e s u n t o c o m p l e t e it s a p p a r e n t j o u r

n e y t h r o u g h t h i s d i s t a n c e .

Where is thetime center forthe whole world?

O n e y e a r a f t e r t h e U n i t e d S t a t e s C o n

g r e s s s e t u p s t a n

d a r d t i m e z o n e s ,

a n i n t e r n a t i o n a l

b o d y a g r e e d o n a

c o r r e s p o n d i n g s y s t e m f o r c o u n t r i e s

e v e r y w h e r e . S t a r t i n g w i t h 0 a t G r e e n

w i c h , E n g l a n d , t h e 3 6 0 o f t h e g l o b e

w e r e s p l i t u p i n t o 2 4 s t a n d a r d t i m e

m e r i d i a n s o f 1 5 e a c h . T h e 2 4 m e r i d

i a n s a r e o n e h o u r a p a r t i n t i m e a n d a r e

t h e b a s i s f o r e x a c t t i m e d e t e r m i n a t i o n s

o n t h e e n t i r e g l o b e .

T h e R o y a l O b s e r v a t o r y , f o r m e r l y a t

G r e e n w i c h a n d n o w a b o u t t h i r t y m i l e s

a w a y a t H e r s t m o n c e u x , k e e p s t i m e f o r

a l l n a t i o n s a n d s e n d s o u t t e l e g r a p h a n d

r a d i o s i g n a l s t h a t a r e p i c k e d u p b y s h i p s ,

o t h e r o b s e r v a t o r i e s a n d a s t r o n o m e r s .

N a v i g a t o r s o n s h i p s c a l c u l a t e t h e i r l o n

g i t u d e b y s u b t r a c t i n g t h e l o c a l t i m e f r o m

G r e e n w i c h M e a n T i m e a n d m u l t i p l y i n g

t h e d i f f e r e n c e b y 1 5 . I f i t i s 3 : 0 0 P . M .

G r e e n w i c h t i m e a n d t h e l o c a l t i m e o n

b o a r d s h i p i s 1 : 0 0 P . M . , t h e d i f f e re n c e

i s t w o h o u r s , w h i c h m e a n s t h e s h i p i s i n

l o n g i t u d e 3 0 w e s t .

U . S . E a s t e r n S t a n d a r d T i m e i s 5 h o u r s

b e h i n d G r e e n w i c h T i m e

U . S . C e n t r a l S t a n d a r d T i m e i s 6 h o u r s


U . S . M o u n t a i n S t a n d a r d T i m e i s 7 h o u r s


U . S . P a c i f i c S t a n d a r d T i m e i s 8 h o u r s


PACIFIC TIME

American StandardTime zones: The time isone hour earlier in eachzone to the west. At1 1 :00 A.M. EasternStandard Time, it is10:00 A.M. Centra lStandard Time, 9:00A.M. Mountain Standard Time, and 8:00A.M. Pacific Standard

Time.

MOUNTAIN TIME CENTRAL TIME EASTERN TIME.

2 6


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1 A./2 A.M.

3 ^ M H I

. 12 P.M.* 11 P.M.

**~r

r J r '

^ ^ ^ ' m

2 P.M.1 P.M.

Pallas '

10 P.M.

& '

7 P.M.

# \

% 6 P.M.

5fP.M.

4 P.M. /

y

The international Standard Time Zones are based on the 0 zone at Greenwich being equal to noon.

STANDARD TIMES IN DIFFERENT CITIESOF THE WORLD

I n s o m e c o u n t r i e s t h e s t a n d a r d t i m e

d i ff e rs f r o m t h e a s s i g n e d m e r i d i a n t i m e

b e c a u s e o f s p e c i a l l o c a l o r n a t i o n a l r e

q u i r e m e n t s . T h e s t a n d a r d t i m e i n s ev

e r a l f o r e i g n c i t ie s i s c o m p a r e d b e l o w

w i t h t h a t o f N e w Y o r k C i t y a t 1 2 : 0 0n o o n E a s t e r n S t a n d a r d T i m e .

A m s t e r d a m

B a n g k o k

B o g o t a

B u e n o s A i r e s

D e l h i

H a v a n a

6 : 0 0 P . M .

1 2 : 0 0 M i d .

1 2 : 0 0 N o o n

( s a m e t i m e )

2 : 0 0 P . M .

1 0 : 3 0 P. M .

1 2 : 0 0 N o o n

( s a m e t i m e )

H o n g K o n g

L o n d o n

M o s c o w

P a r i s

M e x i c o C i t y

T o k y o

1 : 0 0 A . M .

( n e x t m o r n i n g )

5 : 0 0 P . M .

8 : 0 0 P . M .

6 : 0 0 P. M .

1 1 : 0 0 A . M .

2 : 0 0 A . M .

( n e x t m o r n i n g )

2 7


30/52

The imaginary line at the 180th meridian is the International Date Line. Notice how the Date Line curves awayfrom the 1 80th meridian to avoid cutting through the eastern tip of Asia and some of the Island groups.

H a l f w a y a r o u n d t h e g l o b e f r o m G r e e n

w i c h , a t t h e 1 8 0 m e -

H o w c a n ridian o f l o n g i t u d e , i s

. S 6 | . t h e I n t e r n a t i o n a l D a t eg a i n a d a y ?

L i n e , w h e r e t h e d a y

b e g i n s . H e r e , t o d a y m a y b e c o m e t o m o r

r o w o r i t m a y c h a n g e i n t o y e s t e r d a y ,

d e p e n d i n g o n y o u r d i r e c t i o n o f t r a v e l .

E a c h s i d e o f t h e D a t e L i n e h a s a

d i f f e r e n t d a y . T o t h e w e s t i t i s a d a y

l a t e r ; t o t h e e a s t a d a y e a r l i e r . W h e n

y o u s t a r t o u t f r o m t h e w e s t o n a S u n d a y

a n d c r o s s t h e D a t e L i n e , t h e d a y b e

c o m e s y e s t e r d a y , o r S a t u r d a y . R e v e r s i n g

y o u r r o u t e a n d t r a v e l i n g o n a S a t u r d a y

f r o m e a s t t o w e s t , t h e d a y b e c o m e s t o

m o r r o w , o r S u n d a y . T h e w h o l e w o r l d

h a s t h e s a m e d a y o n l y o n t h e i n s t a n t

t h a t m i d n i g h t o c c u r s o n t h e D a t e L i n e .

f la w i n o u r m e a s u r e m e n t of t h e e a r t h '

r o t a t i o n , s o t h a t a m o r e a c c u r a t e s t u d y

o f t h e h e a v e n s i s p o s s i b l e .

A f t e r t h e e a r t h h a s c o m p l e t e d a f u l

r o t a t i o n o f 3 6 0 , i t m u s t t u r n a p p r o x i

m a t e l y 1 m o r e t o r e s u m e t h e s a m

r e l a t i v e p o s i t i o n it h a d t o t h e s u n 2 4h o u r s e a r l i e r . T h e s m a l l a d d i t i o n a l t u r n

e n a b l e s t h e e a r t h t o c o m p e n s a t e f o r t h

d i s t a n c e i t t r a v e l s i n o r b i t w h i l e i t r o

t a t e s . A m o r e a c c u r a t e m e a s u r e m e n t o

t h e 3 6 0 r o t a t i o n i s p o s s i b l e if t h e e a r t h

i s c h e c k e d a g a i n s t a b r i g h t s t a r w h o s

g r e a t d i s t a n c e m a k e s t h e a m o u n t o

e a r t h ' s o r b i t a l t r a v e l o f l i t t l e m a t h e

m a t i c a l i m p o r t a n c e . T h e s i d e r e a l d a yp r o d u c e d b y t h i s m e a s u r e m e n t i s t h

t i m e t h a t t h e e a r t h r e q u i r e s t o c o m p l e t

o n e r o t a t i o n w i t h r e s p e c t t o t h e s t a r s

T h e c a l c u l a t i o n s o f a s t r o n o m e r s f re

q u e n t l y r e q u i r e t h e u s e of

sidereal time ( f r o m sidus

t h e L a t i n w o r d f o r s t a r ) .

S i d e r e a l t i m e , o r s t a r t i m e , c o r r e c t s a

What i sstar time?

T h e d a y c a l c u l a t e d b y t h e s t a r s i s a b o u

4 m i n u t e s s h o r t e rW h y i s s t a r . .,. _. ._ t h a n t h e m e a n s o

t i m e u n p r a c t i c a l ?

l a r d a y a n d c a nn o t b e u s e d f o r r e g u l a t i n g c i v i l a f f a i r s . I

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w e t r i e d t o k e e p t i m e b y t h e s i d e r e a l

s y s t e m , w h i c h is a l w a y s a h e a d o f t h e

s u n ' s c y c l e , t h e s i d e r e a l c l o c k w o u l d

l o s e 4 m i n u t e s f r o m e v e r y s o l a r d a y .

B e c a u s e t h e l o s t m i n u t e s w o u l d a d d u p

f r o m d a y t o d a y , t h e c l o c k s a n d w a t c h e st h a t w e u s e , w h i c h a r e g u i d e d b y t h e

p o s i t i o n o f t h e s u n , w o u l d b e c o m e p r a c

t i c a l l y u s e l e s s .

O n a b o u t M a r c h 2 1 , w h e n t h e n o o n

s u n is d i r e c t l y o v e r h e a d , b o t h t h e s ide

r e a l a n d s o l a r s y s t e m s h a v e t h e s a m e

t i m e . O n e m o n t h l a t e r , a p e r s o n w h o

l i v e d b y t h e s i d e r e a l s y s t e m w o u l d f i n d

t h a t a t n o o n s o l a r t i m e h i s c l o c k r e a dt w o P. M . T h r e e m o n t h s a f te r M a r c h

2 1 , i n s t e a d of i n d i c a t i n g n o o n , h i s c l o c k

w o u l d t e l l h i m t h a t i t w a s s ix P . M .

R e g u l a r e v e n t s , l i k e m e a l s , w o r k i n g

h o u r s , a n d s l e e p w o u l d f o l l o w a c o n

f u s i n g s c h e d u l e t h a t c h a n g e d d a i l y .

A s t r o n o m e r s w o r k w i t h t h e s i d e r e a l

s y s t e m , b u t t h e c l o c k s a n d w a t c h e s t h a t

w e u s e f o r o r d i n a r y p u r p o s e s a r e r e g ul a t e d t o m e a n s o l a r t i m e .

What t ime systemis used by thearmed services?

W e d i v i d e t h e d a y i n t o t w o 1 2 - h o u r

p e r i o d s , a n d a l

t h o u g h t h e h o u r s

a r e c a l c u l a t e d

f r o m t h e p o s i

t i o n o f t h e n o o n s u n , t h e d a y i ts e l f o f

fic ia lly s t a r t s a t m i d n i g h t . T h e f ir st 1 2h o u r s a r e d e s i g n a t e d A . M . ( f r o m t h e

L a t i n ante meridiem m e a n i n g b e f o r e

n o o n ) , a n d t h e 1 2 h o u r s t h a t f o l l o w

n o o n a r e d e s i g n a t e d P. M . ( f r o m t h e

L a t i n post meridiem m e a n i n g a f t e r

n o o n ) .

T h e U n i t e d S t a t e s m i l i t a r y f o r c e s a n d

s o m e E u r o p e a n c o u n t r i e s a v o i d t h e p o s

s i b i li t ie s o f e r r o r a n d c o n f u s i o n i n t h e

A . M . a n d P . M . s y s t e m b y u s i n g a 2 4 -

h o u r c l o c k . H e r e a r e s o m e e x a m p l e s o f

t h e 2 4 - h o u r c l o c k :

.M. AND P.M. CLOCK

9 : 0 0 A . M .

2 : 1 5 A . M .1 2 : 0 0 n o o n

1 2 : 0 0 m i d n i g h t

3 : 3 0 P . M .

1 1 : 5 9 P . M .

24-HOUR CLOCK

0 9 0 0

0 2 1 51 2 0 0

0 0 0 0

1 5 3 0

2 3 5 9

How are the hours ofdaylight increased?

A n o t h e r c h a n g e i n t h e t i m e s y s t e m ,

k n o w n a s

D a y l i g h t S a v -

i n g T i m e ,c r e a t e d e x t r e m e s o f a n t a g o n i s m a n d

p o p u l a r a p p r o v a l w h e n i t w a s fi rs t di s

c u s s e d b y t h e p u b l i c .

T h e L o n d o n b u i l d e r , W i l l i a m Wi l -

l e t t , w h o p r o p o s e d D a y l i g h t S a v i n g

T i m e i n 1 9 0 7 , w a n t e d t o g i v e p e o p l e

m o r e o p p o r t u n i t y t o e n j o y t h e o u t d o o r s

a f t e r t h e y finished w o r k . H e s u g g e s t e d

t h a t t h e b e s t w a y t o g a i n s u c h l e i s u r e

A 24-hour clock eliminates possible confusion.

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w a s t o a d v a n c e t h e c l o c k o n e h o u r d u r

i n g t h e t i m e o f l o n g s u m m e r d a y l i g h t .

W i l l e t t w a s p r o m p t l y c a l l e d a h u

m a n i t a r i a n b y h i s a d m i r e r s . W i t h e q u a l

p r o m p t n e s s , h e w a s c a l l e d a l u n a t i c b y

m a n y d e t r a c t o r s , s o m e o f w h o m a c

c u s e d h i m o f m e d d l i n g w i t h " G o d ' s

t i m e . " O f c o u r s e t h e r e i s n o t i m e k e e p i n g

s y s t e m , e i t h e r s c ie n t i f ic o r r e l i g i o u s ,

t h a t c a n b e c a l l e d G o d ' s t i m e . E v e r

s i n c e a s t r o n o m y b e c a m e a s c i e n c e , t h e

Farmers frequently oppose Daylight Savings Time.They claim, with understandable indignation, thatthey and their livestock get up early enough evenwhen the clock is set at Standard Time.

h o u r s t h a t g o v e r n t h e d a y h a v e b e e n

c h a n g e d b y f o r w a r d t h i n k i n g m e n w h o

h o p e d t o b e t t e r o u r w a y o f l i v i n g .

D a y l i g h t S a v i n g T i m e w a s t r i e d b y

E n g l a n d a n d t h e U n i t e d S t a t e s d u r i n g

t h e first W o r l d W a r a s a c o n t r o l f o r r e

d u c i n g f u e l a n d p o w e r c o n s u m p t i o n .

S i n c e t h e n i ts a d o p t i o n h a s b e e n n a t i o n

w i d e i n E n g l a n d , b u t i n o u r c o u n t r y t h e

u s e o f D a y l i g h t S a v i n g T i m e i s l i m i t e d

t o t h o s e c o m m u n i t i e s a n d s t a t e s t h a t

f a v o r i t . D a y l i g h t S a v i n g T i m e i n t h e

U n i t e d S t a t e s g e n e r a l l y r e q u i r e s t h a t

c l o c k s b e t u r n e d a h e a d 1 h o u r a t t h e e n d

o f A p r i l a n d t h e n t u r n e d b a c k 1 h o u r

a t t h e e n d o f S e p t e m b e r o r O c t o b e r .

HOW TO CHECK YOUR WATCH BY THE STAR

F o l l o w t h e p a t h of a s t a r f o r 2 c o n

s e c u t i v e n i g h t s , a n d y o u w i l l d i s c o v e r

h o w a s t r o n o m e r s u s e t h e u n i v e r s e t o

c h e c k t i m e . O n t h e s e c o n d n i g h t y o u

w i l l s e e t h e s t a r a p p e a r a t t h e i d e n t i c a l

s p o t i n t h e h e a v e n s 3 m i n u t e s a n d 5 6

s e c o n d s e a r l i e r t h a n i t d i d o n t h e first

n i g h t . T h u s if a s t a r i s i n a c e r t a i n p o s i

t i o n a t 9 : 1 5 P . M . , t h e n e x t n i g h t it w i ll

b e i n t h e s a m e p o s i t i o n a t 4 s e c o n d s

a f t e r 9 : 1 1 P. M . Y o u c a n u s e t h i s d e

p e n d a b l e t i m e r e l a t i o n s h i p b e t w e e n t h e

e a r t h a n d t h e s t a r s t o find o u t h o w a c

c u r a t e l y y o u r w a t c h k e e p s t i m e .

S t a n d a t a w i n d o w t h a t f a c e s s o u t h

a n d s e l e c t a c h i m n e y o r t h e e d g e of a

h i g h b u i l d i n g t o b e y o u r r e f e r e n c e g u i d e .

T h e n t a p e a p i e c e o f c a r d b o a r d w h i c h

h a s a s m a l l h o l e i n i t t o t h e w i n d o w .

T h e c a r d b o a r d s h o u l d b e p o s i t i o n e d s o

t h a t y o u c a n s e e t h e r e f e r e n c e g u i d e a n d

a l s o o b s e r v e s o m e o f t h e n e a r b y s t a r s

D o n o t c o n f u s e a s t a r w i t h a p l a n e t .

B e c a u s e o f t h e i r g r e a t d i s t a n c e f r o m t h e

e a r t h , s t a r s g e n e r a l l y a p p e a r s m a l l e r

t h a n p l a n e t s . T h e y h a v e a t w i n k l i n g

l i g h t , w h i l e p l a n e t s re f l e c t a s t e a d y,

m o r e c o n s t a n t l i g h t . A n o t h e r a n d p e r

h a p s b e t t e r w a y t o t e l l w h e t h e r a b o d y

i n t h e h e a v e n s is a s t a r o r a p l a n e t , i s t o

s t u d y i t s m o v e m e n t f o r a f e w n i g h t s .

A p l a n e t m o v e s i n d e p e n d e n t l y i n t o n e w

p o s i t i o n s w h e n o b s e r v e d a g a i n s t t h e

b a c k g r o u n d of t h e o t h e r h e a v e n l y b o d

i e s ; s t a r s a p p e a r t o m o v e i n g r o u p s o r

c o n s t e l l a t i o n s .

A f t e r y o u h a v e v i e w e d t h e m o v e

m e n t s of s o m e o f t h e s t a r s t o w a r d s y o u r

b u i l d i n g o r c h i m n e y r e f e r e n c e g u i d e ,

c h o o s e o n e of t h e m f o r y o u r t i m e e x p e r i -

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m e n t . A s s o o n a s t h i s s t a r d i s a p p e a r s

b e h i n d t h e r e f e r e n c e g u

how and why wonder book of time

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