01 intro to ast

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INTRODUCTION TO

ASTRONOMY

What is Astronomy ?

Astronomy is NOTAstrology

Why do we stdy Astronomy ?


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Astronomy - the scientific

study of the Universebeyond Earth

Astronomy is a tre s!ien!e" It in!ldes the

to#i!s o$ the history o$ astronomy% hman

s#a!e eloration% or Sn and Moon% #lanets%other stars% gala&ies% and !osmology 'the

origin% str!tre% and $ate o$ the whole

Uni(erse)"


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Astronomy is a Tre S!ien!e

Astronomy is *ased on o*ser(ations and

eeriments that !an *e re#eated% and that gi(e the

same reslts no matter who does the eeriment orma+es the o*ser(ation"

Astronomy ma+es #re!ise #redi!tions a*ot or

Uni(erse that !an *e tested to see i$ the #redi!tions

are tre or not"

Astronomy ma+es se o$ other well,esta*lished

s!ien!es li+e #hysi!s and !hemistry"


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Astrology is NOT a S!ien!e

See+s to dis!o(er -hidden +nowledge. *y

the inter#retation o$ omens 'li+e reading tea

lea(es)" Reslts are not re#eata*le"

/redi!tions are (age and not testa*le"

Does not in!or#orate s!ien!es li+e

!hemistry and #hysi!s"


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Why do we stdy Astronomy ?

Natral disasters

Re!reation and estheti!s

S!ienti$i! in0iry and !riosity 1d!ation o$ an in$ormed so!iety 'yo 2)

Or #la!e in the Uni(erse

Origin and $ate o$ the Uni(erse 'Cosmology) Tre S!ien!e (erss s!ien!e $i!tion


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Natral Disasters

Comet and meteorite im#a!ts% $or e&am#le"


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BOOM !!


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Re!reation and 1stheti!s

The Uni(erse is *eati$l"


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S!ienti$i! In0iry and Criosity

3or e&am#le 4 or instrments !an see what

or eyes !annot"

S#a!e eloration"


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Satrn 4 Di$$erent 5inds o$ 6ight


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Satrn 4 Di$$erent 5inds o$ 6ight

Ultra(iolet 7isi*le

In$rared Radio


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S#a!e 1loration


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1d!ation o$ an In$ormed So!iety


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Or /la!e in the Uni(erse

Where are we?


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THE SCALES OFTHE SCALES OF

THE UNIVERSETHE UNIVERSE

The range of objects

we study are from the

extremely smallsubatomic particles,

to objects which are

gigantic, such as a

galaxy or the size of

the known universe

itself.

Each division up the

line indicates an

increase in size by

1,.


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The ni(erse is hge% and the si8es and distan!es o$ o*9e!ts in

the ni(erse (ary greatly" There$ore we se s!ienti$i! notation%

whi!h in(ol(es #owers o$ ten notation to des!ri*e nm*ersm!h smaller or m!h greater than :"


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Units o$ Distan!e +ilometers

4$or radii o$ the #lanets% the Sn% et!"

astronomi!al nits4$or distan!es *etween solar system *odies

4de$inition; the a(erage distan!e *etween the 1arth and

Sn '%>>>%>>> +m :"= & :>@

+m) Astronomi!al Units 'AUs) measre distan!es *etween

#lanets 'or solar system)

: AU is a*ot :=> million +m


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1 AU

Sn 1


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Mer!ry is the !losest at >"B AUs while

Ne#tne is the $arthest at >"> AUs


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light years

4$or distan!es *etween stars and gala&ies

4de$inition; the distan!e light tra(els in one year'%>>>%>>>%>>>%>>> +m :>:A+m %>>>

AU)

/arse! is sed to measre greater distan!es*etween stars and gala&ies

: #arse! " light years


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/aralla& is sed to measre the distan!e to

near*y stars

/aralla&; when o*9e!ts a##ear to mo(e or

shi$t de to earthEs or*it

This method ses trigonometry

near*y stars >> light years or less


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/aralla&


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!.". # !stronomical "nit # distance from Earth to $un


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$tellar %arallax

!s Earth moves from one

side of the $un to the

other, a nearby star willseem to change its

position relative to the

distant background stars.

d # 1 & p

d # distance to nearby

star in parsecs

p# parallax angle of that

star in arcseconds


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'loser star ( larger parallax


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Si8es o$ Astronomi!al O*9e!ts

How !an we measre the si8es o$astronomi!al o*9e!ts?

The same way that we measre distan!es 4sing triangles


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The Small-Angle Formula D linear si8e o$ o*9e!t

) anglar si8e o$ o*9e!t

'in ar!se!onds)

d distan!e to the o*9e!t>=

d

D

=


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On No(em*er @% >>>% #iter was >B million

+ilometers $rom 1arth and had an anglar diameter

o$ J@"F" Using the small,angle $ormla% determine#iterEs a!tal diameter"

D J@"F & >B%>>>%>>> +m G >= :J%>>> +m

The Small-Angle Formula D linear si8e o$ o*9e!t) anglar si8e o$ o*9e!t

'in ar!se!)

d distan!e to the o*9e!t

>=

dD

=


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In(erse s0are law o$ light is sed $or

distant stars

the intensity o$ light $alls o$$ as thes0are o$ the distan!e $rom the sor!e


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: K light years away


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=> light years away


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= thosand light years away


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=>> thosand light years away


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= million light years away


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=> thosand light years away


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:>> million light years away


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*illi li h


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: *illion light years away

:J *illi li h


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:J *illion light years away


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Origin and 3ate o$ the Uni(erse

This #art o$ Astronomy is !alled

Cosmology"

Cosmology see+s a s!ienti$i! elanation$or how the Uni(erse *egan and how it

might end 'or will it go on $ore(er?)"

How did the universe begin??


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How did the universe begin??

There are three main theories of

the origin of the universe.

ig ang theory

Steady State theory

!reation theory


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"od created the Heavens and the

Earth.

Adam and Eve

#eligion


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The universe has always been as

it is today

$ew matter is always being

%roduced

The universe is continuously

contracting and e&%anding.


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Billions of years ago the universe waspacked in a small space-Primeval

AtomIt explodes and threw matter in alldirections

The explosion caused the formationof the galaxies.

Th L i i Th Li L


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The Leginning 4 The Lig Lang


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'HAT () *)U TH+$,?

'hat does the Universe include?

(id the Universe have a beginning?

+s the Universe e&%anding fi&ed in sie orcontracting?

'ill the Universe last forever?


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*ou will discover/

Cosmology% whi!h see+s to elain how theUni(erse *egan% how it e(ol(es% and its $ate"

The *est theory we ha(e $or the e(oltiono$ the Uni(erse 4 the Lig Lang"

How astronomers elain the o(erallstr!tre o$ the Uni(erse"

Or nderstanding o$ the $ate o$ theUni(erse"


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In the Leginning 4 the Lig Lang

The Uni(erse *egan :" *illion years ago with an

e(ent !alled the -Lig Lang".

All o$ s#a!e,time% matter% and energy were !reated at

the Lig Lang" The le$t,o(er energy $rom the Lig Lang !an *e

dete!ted today as the Cosmi! Mi!rowa(e La!+grond

Radiation"

The tem#eratre o$ this radiation is only a $ew

degrees a*o(e a*solte 8ero"

The Leginning The Lig Lang


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The Leginning 4 The Lig Lang

+n Search of The Earliest 0hotons


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+n Search of The Earliest 0hotons

Wilkinson Microwave Anisotropy Probe

(WMAP) satellite% lan!hed in >>:


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WMA/Es La*y /i!tre o$ the Uni(erse 4

Cosmi! Mi!rowa(e La!+grond Radiation


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The Uni(erse is 1anding

The Redshi$t o$ S#er!lsters shows s that

the Uni(erse is eanding" This Redshi$t is

!alled the -Cosmologi!al Redshi$t%. *e!ase

it is !ased *y the eansion o$ s#a!e"

The $arther away a gala&y is $rom s% the

$aster it mo(es away $rom s"

The E&%ansion of the Universe 1


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!osmological #edshift

S#a!e itsel$ is eanding"

E&%anding !a2e Analogy


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E&%anding !a2e Analogy

st as all the !ho!olate !hi#s mo(e a#art as the !a+e rises%

all the s#er!lsters o$ gala&ies mo(e away $rom ea!h other

as the s#a!e o$ the Uni(erse eands"

The )bservable Universe


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The )bservable Universe

The !osmi! light hori8on today is a*ot :" *illion

light,years away in all dire!tions"

HST 1 "ala&ies 345 illion 6* Away


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y

ThisHST Ultra

Dee# 3ield

Teles!o#e imageshows some o$

the most distant

gala&ies we

ha(e seen"

Early Universe Tem%erature 7ariations


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y %

Tiny tem#eratre $l!tations in the Cosmi! Mi!rowa(e La!+grond

Radiation are related to the large,s!ale str!tre o$ the Uni(erse today%

indi!ating where S#er!lsters and (oids grew"

The First Stars 1 much larger than the Sun 1 with


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much shorter lives

The *rst o$ star $ormation that o!!rred within a $ew

hndred million years a$ter the Lig Lang"

0roto-"ala&y Formation


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0roto "ala&y Formation

H**le and 5e!+ teles!o#e images o$ two gro#s o$ stars that are

*elie(ed to *e #roto,gala&ies% $rom whi!h *igger gala&ies grew

!reation of S%iral and Elli%tical "ala&ies


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% %

A gala&y *egins as a hge !lod o$ #rimordial gas

that !olla#ses gra(itationally"

I$ the rate o$ star

$ormation waslow% then a s#iral

gala&y $ormed"

I$ the rate o$ star

$ormation was

high% then an

elli#ti!al gala&y

$ormed"

The 3ate o$ the Uni(erse


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The 3ate o$ the Uni(erse

The $ate o$ the Uni(erse de#ends on the sha#e

o$ s#a!e,time"

The sha#e o$ s#a!e,time is determined *y how

m!h total matter and energy there is in the

Uni(erse"

S#a!e,time !old ha(e one o$ three sha#es;

S#here #ositi(e !r(atre !losed"

Or $loor no !r(atre $lat"

Saddle negati(e !r(atre o#en"

0ossible Sha%es of S%ace-time


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% %

and the Fate of the Universe

Closed 4Uni(ersewold!olla#se"

3lat 4Uni(erse!old slowlyeand$ore(er"

O#en 4Uni(ersewold eand$ore(er"

!osmic 8icrowave ac2ground indicates that S%ace-time is

Fl t U i ld l l d f


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Flat 1 Universe could slowly e&%and forever

UT 1 dimmer distant Su%ernovae mean the

i f th U i i di


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e&%ansion of the Universe is s%eeding u%.


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:>> *illion years$rom now the

Uni(erse will a##ear

$ro8en in time as we

loo+ ot into s#a!e"Only the light $rom

the 6o!al ro# o$

gala&ies will remain

(isi*le% i$ anyone is

still arond to see it"

1ansion o$ the Uni(erse is s#eeding #


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# # g #

7ery distant Ty#e :a S#erno(ae are not as *right asthey shold *e"

This means the eansion o$ the Uni(erse is s#eeding# instead o$ slowing down or staying the same"

There is something really weird !alled Dar+ 1nergy

'not the same as Dar+ Matter) that is !asing thisa!!eleration"

Dar+ 1nergy a!ts li+e anti,gra(ity% #shing theUni(erse a#art"

We do not +now what this Dar+ 1nergy is% *t itma+es # o$ the total energyGmatter o$ theUni(erse"

Com#osition o$ the Uni(erse


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S##ose all the matter and energy in the Uni(erse is P:>> inyor wallet or #rse"

P wold *e Dar+ 1nergy 4 the mysterios energy thatEs#shing the Uni(erse a#art $aster and $aster"

P wold *e Dar+ Matter 4 matter that doesnEt gi(e o$$ any+ind o$ radiation% so we !anEt see it 4 *t it does ha(e gra(ity"

So ot o$ yor Uni(erse o$ P:>>% PB re#resents Dar+ 1nergyand Dar+ Matter that ha(e yet to *e identi$ied"

Only PJ wold *e (isi*le matter 4 the reglar st$$ we !an see%li+e stars% gas !lods% and dst 4 the same st$$ weEre made o$"

O$ the (isi*le matter 'PJ)% only one,tenth o$ it shines as stars"ThatEs J> !ents ot o$ yor total P:>>" The rest o$ the (isi*lematter is gas !lods and dst"



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'HAT (+( *)U TH+$,?


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What does the Universe include

It is all the matter% energy% and s#a!e,time that wille(er *e dete!ta*le $rom the 1arth or that will e(era$$e!t s"

Did the Universe have a beinnin

Yes% it o!!rred a*ot :" *illion years ago in ane(ent !alled the Lig Lang" "s the Universe e#pandin$ %i#ed in si&e$ or

contractin

The Uni(erse is eanding% $aster and $aster" Will the Universe last %orever Crrent o*ser(ations s##ort the *elie$ that it will last

'eand) $ore(er"

Th i i d $


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The ni(erse is made # o$

millions o$ ala&ies"

A gala&y is a swarm o$ *illions o$stars% !lods and dst rotating

arond a !entral #oint"

O l i


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Our galaxy is

called the MilkyWay

)ur'H)6E

solar system

is locatedright about

here

X


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:>> *illi


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:>> *illion years

$rom now the

Uni(erse willa##ear $ro8en in

time as we loo+

ot into s#a!e"

Only the light$rom the 6o!al

ro# o$ gala&ies

will remain

(isi*le% i$ anyone

is still arond to

see it"

Tre S!ien!e (erss


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Tre S!ien!e (erss

S!ien!e 3i!tion

Some astronomy st$$ may *e weird% LUT

ITES TRU1"

Lla!+ Holes"

Radiation $rom the *eginning o$ the Uni(erse"

S!ien!e $i!tion is 9st weird"

3a(orite mo(ies"

A S#inning Lla!+ Hole


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A S#inning Lla!+ Hole

Radiation $rom the Leginning o$ the


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Uni(erse :" *illion years ago


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History o$ Astronomy

Where did -real. astronomy *egin?

What did we +now a*ot astronomy >>>Q years ago

Who dis!o(ered some o$ the *asi! #rin!i#les o$Astronomy 4 and how?

What tools did they se *a!+ then?

Why did they get into Astronomy?

When were ma#s o$ s+y !reated?

When were !onstellations -in(ented.?


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Why were #eo#le interested in Astronomy?

4Calendars

4/lantingG3arming de#ends on seasons4Religion Astrology

4Na(igation

4Time+ee#ing46and Sr(eying


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Timelines;

4 Most o$ s thin+ Astronomy really *egan with alileo%

Co#erni!s% Lrahe% et!"

4 Most o$ s thin+ Astronomy really *egan with the se o$ ateles!o#e and modern te!hnology"

4 Most $a!ts a*ot Astronomy were -+nown. thosands o$

years ago withot the so#histi!ated tools we ha(e today 4

*t% they did se so#histi!ated reasoning and mathemati!s


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Archeoastronomy

4The stdy o$ An!ient Astronomy in an!ient

!i(ili8ations

We stdy an!ient sites and rins to determine what

these !i(ili8ations +new a*ot astronomy

We donEt ha(e re!ord o$ who set # the rins we stdy

today

We do +now a little a*ot what they +new *y loo+ing

at the rins and stdying the geometry and alignment

o$ these sites"


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Some $amos Ar!haeoastronomy Sites;

4Na*ta; Megalithi! Site 4 :>>> years *e$ore

Stonehenge Cir!les o$ stones mar+ing solsti!es and !ardinal

#oints more than >>> years ago in Sothern 1gy#t

4Stonehenge; :>> LC to >>>LC

4Mesoameri!an Site; :=>> LC to :=>> AD

4Na8!a 6ines in /er; >> LC to @>> AD


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Ar!haeoastronomy ended a*ot >> LC in

ree!e

A$ter ar!haeoastronomy% we had writtenre!ords o$ the e(ents that o!!rred"

Not always :>> a!!rate% *t astronomers

*egan writing ot their reasoning


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Who were the earliest Astronomers?

4 Thales o$ Milets% Asia Minor

4 /ythagoras o$ Samos

4 Demo!rits o$ A*dera% ree!e

4 Oeno#ides o$ 5hios% ree!e

4 Aristotle or Athens% ree!e

4 Aristar!hs o$ Samos

4 1ratosthenes o$ Cyrene% North 6i*ya

4 Hi##ar!hs o$ Rhodes

4 /tolemy o$ Ale&andria% 1gy#t


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Thales; J to =J LC4Said to ha(e #redi!ted a solar e!li#se in =@= LC

4ree+s already +new a*ot the :B year !y!le$or lnar e!li#ses

4Measred the height o$ the #yramids *ynderstanding -similar triangle. theory.;

Measre the shadow length at the time o$ daywhen yor shadow is as long as yo are"

4De(elo#ed early geometri! theorems


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/ythagoras; =@>,=>> LC4-In(ented. some o$ the math that was needed to

get a s!ienti$i! *asis $or astronomi!al !al!lations

4 /ythagorean Theorem222243irst to note that the morning and e(ening stars

were *oth 7ens

4Lilt #on Ana&imanderEs ideas% who #ostlatedthat #lanets and stars go arond in #er$e!t !ir!les"

4Still *elie(e geo!entri! model o$ ni(erse


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Demo!rits; J> 4 @> LC

4De(elo#ed the !on!e#t o$ the atom; all things

were made o$ mi!ros!o#i! and indi(isi*le%indestr!ti*le atomi! #arti!les

4He nderstood that the Mil+y Way was a large

!olle!tion o$ stars and also thoght s#a!e was

limitless


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Oeno#ides; J=> LC4 /o#lari8ed the : signs o$ the odia!

4 /ro*a*ly !o#ied them $rom the Assyrians in Meso#otamia'Ar!haeoastronomy2222)

4 3irst to $i& the angle o$ the e!li#ti! with the !elestial e0ator 4!alled it J degrees '1arthEs Tilt is a!tally K degrees)

4 3i&ed the year to *e = days long

4 /ostlated that the -reat Year. 4 the nm*er o$ years when themotion o$ the sn and the moon e&a!tly re#eated their motion 4

was =B years4 Oeno#ides reslt lead to a lnar month o$ B"=>: days% whi!h is

remar+a*ly !lose to the modern (ale o$ B"=>=B days


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Aristotle; @J 4 LC

4 Did his *est wor+ on !lassi$ying #lants and animals

4 Too+ a 0alitati(e a##roa!h to s!ien!e

4 Did not se mathemati!s in his stdies

4 1arth% air% $ire and water were the elements

4 Lelie(ed the earth was immo*ile 'eo!entri!)

4 Stars and #lanets se the /ythagoras !ir!lar s#heres model

4 Re,dis!o(ered in the late Middle Ages% and sed to im#ede

o*ser(ational s!ien!e


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Aristar!hs; :>,> LC

4Lelie(ed in the Helio!entri! Uni(erse

41stimated the distan!e o$ the moon and sn4Utili8ed e&!ellent mathemati!al #rin!i#les *t

la!+ed the tools to get the o*ser(ational data

!orre!t

4All o$ his written re!ords were destroyed in the

$ire o$ the li*rary in Ale&andria


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Aristar!hs Mathemati!al enis

4Method o$ determing distan!e *etween sn%

moon and earth
http://upload.wikimedia.org/wikipedia/commons/f/f3/AristarchusHalfLitMoon2.pnghttp://upload.wikimedia.org/wikipedia/commons/f/f3/AristarchusHalfLitMoon2.png


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Aristar!hs Measring the SnEs Si8e


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1ratosthenes; ,:B LC

4De(elo#ed a ma# o$ the world

4De(elo#ed a way to $ind #rime nm*ers41stimated the !ir!m$eren!e o$ the earth

4Measred the tilt o$ the earth

4Sggested that a lea# day *e added to the!alendar e(ery Jthyear


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1ratosthenes Measrements


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Hi##ar!hs; :B> 4 :> LC4 Introd!ed the idea o$ > degrees in a !ir!le4 Cal!lated the length o$ a year within "= mintes4 Cal!lated the moonEs distan!e at *etween =B radii 4 !orre!t

answer is >24 Dis!o(ered #re!ission 4 and !al!lated it at J se!onds #er years 4

!orre!t is =>" se!onds #er year4 De(elo#ed a star !ataloge o$ @=> stars sed later *y /tolemy4 De(elo#ed the !rrently sed magnitde s!ale o$ : 4 4 Dis!o(ered the $irst no(a

4 Measred the distan!e to the moon sing #aralla& Used di$$erent (iews o$ a solar e!li#se Small angle $ormla Distan!e is a*ot J>%>>> miles


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Cladis /tolemy; @=,:= AD4 De(elo#ed the most so#histi!ated model o$ !on!entri!

!ir!les 'e#i!y!les) to determine #lanetary motion

4 He $ollowed the geocentric theory The geo!entri! theory is the theory that the sn% #lanets and

all the other stars or*it arond the earth" The earth is at the!enter o$ the ni(erse2

4 His Almagest had most o$ AristotleEs ideas in it% with a

geo!entri! a##roa!h4 Le!ase it sr(i(ed long #eriods o$ #hea(al and wars% it

was -the. astronomy manal ntil the time o$ Colm*s


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The History o$ Astronomy

What did we +now *a!+ then that was !orre!t% *t-lost. '#eo#le didnEt *elie(e it)"4 The earth is rond

4 Cir!m$eren!eGDiameter o$ the 1arth4 Distan!e to the Moon

4 The Solar System is Heliocentric

The theory that the earth% along with the other #lanets or*itsthe sn2

4 An estimate o$ the distan!e to the sn

4 /re!ision o$ the e0ino&es

4 6ength o$ the year to a high #re!ision


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The History o$ Astronomy

The story does not end here""

4 Most o$ what was +nown was lost again a$ter this -high.

#eriod o$ astronomy in ree!e% Tr+ey and 1gy#t

4 Romans were not m!h interested in astronomy or astrology4 Ara*s !on0ered many o$ these !ontries starting in the th

!entry% and #reser(ed a lot o$ the wor+ done *y the

an!ients% re$ined it% and #assed it *a!+ to the western worlds

at the end o$ Middle Ages

4 Ths it *e!ame the $ondation o$ the wor+ and ideas that

*e!ame #re(alent in the :=th :th!entries

i $


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Lasi! Con!e#ts o$ Astronomy

A constellation is a gro# o$ stars that $orms somesort o$ $igre when #t together

@@ o$$i!ial !onstellations re!ogni8ed *y the

International Astronomi!al Union Thosands o$ years ago% they were names $or

animals or mythologi!al !reatres

Astronomers now se them to distingish di$$erent

areas o$ the s+y" 3or e&am#le% *y saying a #lanet islo!ated in -6eo%. we +now what area o$ the s+y toloo+ in"



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@@ re!ogni8ed !onstellations !an *e $ond *ehindyor glossary in this *oo+let" Their de!lination

and right as!ension is also listed% along with

meaning"

4 Asterisms are #o#lar% no$$i!ial names $or these

!onstellations

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/re!ession o$ 1arth4 Crrently 1arth is tilted K degrees% #ointed right at /olaris

'The North Star)

41(ery %>>> years the 1arthEs a&is tra!es ot an imaginary!ir!le% (ery% (ery slowly222

4 Dring this shi$t% the tilt o$ 1arth will go $rom #ointingdire!tly at /olaris% to #ointing at 7ega and then #ointing atTh*an"

4 The motion o$ 1arthEs a&is is !alled 0recession4 This is the reason yor astrologi!al signs do not ne!essarilymat!h # with the rising at setting o$ the !onstellationsanymore"

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/re!ession o$ 1arth"

Th

*

an

7ega

':J%>>>

AD

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1arth,Sn Relationshi#

7o!a* Words4 Rotation4 Re(oltion4 Terrestrial lo*e

4 6atitde4 6ongitde4 Tro#i! o$ Can!er4 Tro#i! o$ Ca#ri!orn4 10ator4 /rime Meridian

4 Atmnal 10ino&4 7ernal 10ino&4 Winter Solsti!e4 Smmer Solsti!e



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1arth Sn Relationshi#

Terrestrial "lobeis the s#heri!alre#resentation o$ the earth"4 The imaginary line that se#arates the earth

into a Northern and Sothern hemis#here

is the e9uator.4 The imaginary line that se#arates the earthinto a an 1aster and Western hemis#here isthe 0rime 8eridian.

4 6atitudemeasres distan!es North and

Soth o$ the e0ator"4 6ongitude measres distan!es 1ast and

West o$ the /rime Meridian"

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1arth is !onstantly mo(ing in two ways

4It is ta+ing one rotation arond itsel$ ea!h day

A rotation is when an o*9e!t s#ins arond itsel$4It is ta+ing one revolutionarond the sn ea!h

year 4 ="= days

A re(oltion is when an o*9e!t tra(els arond

another o*9e!t

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The earthEs rotation is what gi(es s day

and night

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1arthEs re(oltion is what gi(es s seasons%

*t only *e!ase the 1ARTH IS TI6T1D

AT K D1R11S2222 1arth is !losest to the sn in its re(oltion

in De!em*er and $rthest in its re(oltion in

ne2

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Sn a##ears to shine dire!tly in di$$erent

lo!ations throghot the year"

oes $rom shining at the e0ator to shiningat the Tro#i! o$ Can!er% *a!+ to the e0ator%

down to the Tro#i! o$ Ca#ri!orn and then

*a!+ to the e0ator Re#eats this !y!le o(er and o(er again2

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Tro%ic of !anceris K degrees North latitde

4 3rthest north the sn a##ears to shine dire!tly2

4 Shines here arond ne :st

Tro%ic of !a%ricornis K degrees Soth

latitde

4 3rthest soth the sn a##ears to shine dire!tly2

4 Shines here arond De!em*er :st

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Summer Solstice4 3irst day o$ Smmer

4 The day yor hemis#here is tilted dire!tly towards the sn

4 6ongest day o$ the year

4 Northern Hemis#here it is arond ne :st% Sothern Hemis#hereit is arond De!em*er :st

'inter Solstice4 3irst day o$ Winter

4The day yor hemis#here is tilted dire!tly away $rom the sn4 Shortest day o$ the year

4 Northern Hemis#here it is arond De!em*er :st% SothernHemis#here is it arond ne :st

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Autumnal E9uino&4 3irst day o$ 3all4 The day the sn is shining dire!tly at the e0ator% *t mo(ing away

$rom the hemis#here yo are li(ing in 'towards winter)

4 : hors o$ daylight% : hors o$ dar+ness4 Northern Hemis#here it is arond Se#tem*er :st% SothernHemis#here it is arond Mar!h :st

7ernal E9uino&4 3irst day o$ S#ring4 The day the sn is shining dire!tly at the e0ator% *t mo(ing toward

the hemis#here yo are li(ing in 'towards smmer)4 : hors o$ daylight% : hors o$ dar+ness4 Northern Hemis#here it is arond Mar!h :st% Sothern Hemis#here it

is arond Se#tem*er :st



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#

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A##arent altitde o$ the sn

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