8/9/2019 01 Naked-eye Observations of Sun & Moon

1/46

Lecture 1

Naked-eyeObservations:Sun & Moon

Total Solar Eclipse, 212 Nov 1!,"ustralia

http://apod.nasa.gov/apod/image/1211/tse2012C3shadowbands_StephenMudge.jpghttp://apod.nasa.gov/apod/image/1211/tse2012C3shadowbands_StephenMudge.jpg

8/9/2019 01 Naked-eye Observations of Sun & Moon

2/46

8/9/2019 01 Naked-eye Observations of Sun & Moon

3/46

Sunrise

Te direction o( terisin' Sun can'estrou'out te

year) Only on te

e*uino+es are terisin' point dueeast)

"rny & Scneider, ./0E 1)1!"

8/9/2019 01 Naked-eye Observations of Sun & Moon

4/46

an'in' irection

Te Sun 3ill al3ays rise and set (urtest tote sout durin' te day o( 4interSolstice, and (urtest to te nort durin'

Su%%er Solstice)

.reece

8/9/2019 01 Naked-eye Observations of Sun & Moon

5/46

Eart5s 0otation &0evolution

Te period (ro% one noon to te ne+tis te 26-our solar day) Te dailypro'ress o( te Sun across te sky is

a conse*uence o( Eart5s rotation)

Eart rotates on its central a+is 3ileat te sa%e ti%e resolvin' around

te Sun) Eart takes !78 days to orbit te Sun)

8/9/2019 01 Naked-eye Observations of Sun & Moon

6/46

nclination o( 0otation "+is

Eart5s rotation a+is is inclined at an an'le o(2!)8to te plane o( its orbit)

Te su%%er solstice represents te locationin Eart5s orbit 3ere our planet5s Nort pole

co%es closest to pointin' in te direction o(te Sun) Tis occurs on or near 9une 21)

Si+ %onts later, te Nort #ole points(arter (ro% te Sun) 4e ave reaced te

3inter solstice) Te vernal autu%nal; e*uino+ occurs innortern sprin' (all;, on or near Marc 21Septe%ber 21;)

8/9/2019 01 Naked-eye Observations of Sun & Moon

7/46

8/9/2019 01 Naked-eye Observations of Sun & Moon

8/46

Stoneen'e

#eraps te best-kno3narcaeoastrono%icalsite)

t dates (ro% te Stone"'e)

0esearcers tink it 3asan early astrono%icalobservatory o( sorts%a'ic> %o%ent)

http://www.english-heritage.org.uk/stonehengehttp://news.yahoo.com/michael-johnson-takes-olympic-flame-stonehenge-112314022--oly.html?_esi=1http://antwrp.gsfc.nasa.gov/apod/image/1006/stonehengesun_alexander_big.jpghttp://news.yahoo.com/michael-johnson-takes-olympic-flame-stonehenge-112314022--oly.html?_esi=1http://www.english-heritage.org.uk/stonehenge

8/9/2019 01 Naked-eye Observations of Sun & Moon

9/46

8/9/2019 01 Naked-eye Observations of Sun & Moon

10/46

@eel Stone

On su%%er solstice, as seen(ro% te center o( te stonecircle, te Sun rose directly overte eel stone)

http://viewfinder.english-heritage.org.uk/search/reference.aspx?uid=76018&index=12&mainQuery=stonehenge&searchType=all&form=homehttp://viewfinder.english-heritage.org.uk/search/reference.aspx?uid=76018&index=12&mainQuery=stonehenge&searchType=all&form=home

8/9/2019 01 Naked-eye Observations of Sun & Moon

11/46

"pparent Motion o( te Sun

On te e*uator, 3e3ill observe tat teSun is (artest nortdurin' su%%er

solstice and (artestsout durin' 3intersolstice)

Solar altitude is te

sa%e durin' botsu%%er and 3intersolstice)

http://mydarksky.org/2009/12/22/solstices-and-equinoxeshttp://mydarksky.org/2009/12/22/solstices-and-equinoxes

8/9/2019 01 Naked-eye Observations of Sun & Moon

12/46

Nortern @e%ispere

On te norternand souterne%ispere, te

noonti%e Sun isi'est in te skydurin' su%%ersolstice and lo3est

in te sky durin'3inter solstice)

8/9/2019 01 Naked-eye Observations of Sun & Moon

13/46

"pparent Motion o( te Sun

Te picture is a co%posite o( ourly i%a'estaken o( te Sun above ?ursa, Turkey)

2A ec,4interSolstice

2$9une,Su%%erSolstice

2$Marc,BernalE*uino+

8/9/2019 01 Naked-eye Observations of Sun & Moon

14/46

Seasons

Te tilt o( Eart5s rotation a+is isresponsible (or te seasons)

T3o (actors co%bine to cause te

seasons)1) Tere are %ore ours o( dayli't durin'

te su%%er tan in 3inter)

2) 4en te Sun is i' in te sky in su%%er,rays o( sunli't strikin' Eart5s sur(ace are%ore concentrated tan in 3inter) "s aresult, te Sun (eels otter)

8/9/2019 01 Naked-eye Observations of Sun & Moon

15/46

@ours o( ayli't

"t te e*uino+es,e+actly al( o( tesunCs circular patlies above te

oriDon) n 9une, considerably

%ore tan al( o( tecircle is above te

oriDon) n ece%ber, %uc

less tan al( tecircle is visible)

http://physics.weber.edu/schroeder/ua/SunAndSeasons.htmlhttp://physics.weber.edu/schroeder/ua/SunAndSeasons.html

8/9/2019 01 Naked-eye Observations of Sun & Moon

16/46

Solar @ei'ts

( you took a picture o(te Sun at te sa%e

ti%e eac day, teSun 3ould trace outan anale%%aF overte course o( a year)

3int

er

su%%er

" co%posite o( 67 separate Sunpoto'raps taken durin' 2! in

http://abyss.uoregon.edu/~js/ast122/lectures/lec02.htmlhttp://abyss.uoregon.edu/~js/ast122/lectures/lec02.html

8/9/2019 01 Naked-eye Observations of Sun & Moon

17/46

8/9/2019 01 Naked-eye Observations of Sun & Moon

18/46

Eart5s Elliptical Orbit

Tis co%posite neatly co%pares t3opictures o( te Sun taken 3it te

sa%e telescope and ca%era on tedates o( #erielion closest

http://www.uwsp.edu/geo/faculty/ritter/glossary/A_D/Aphelion.htmlhttp://www.uwsp.edu/geo/faculty/ritter/glossary/A_D/Aphelion.html

8/9/2019 01 Naked-eye Observations of Sun & Moon

19/46

Sunset

Te Sun appears oran'e and di%%er tan at noon)

8/9/2019 01 Naked-eye Observations of Sun & Moon

20/46

Oran'e & i%

0aylei' (ound tat blue li't is %uc %ore easilyscattered tan red li't, basically because te3avelen't o( blue li't 6 n%; is closer to tesiDe o( air %olecules tan te 3avelen't o( red

li't A n%;

8/9/2019 01 Naked-eye Observations of Sun & Moon

21/46

Near te @oriDon

"t dusk, 3it te Sunnear te oriDon,sunli't %ust passtrou' %uc %ore

at%ospere) Te blue co%ponent o(

te Sun5s li't isal%ost entirely

scattered out o( teline o( si't, and evente red co%ponent is

di%inised in intensity)

8/9/2019 01 Naked-eye Observations of Sun & Moon

22/46

8/9/2019 01 Naked-eye Observations of Sun & Moon

23/46

Moon llusion

Te Moon appears tobe very nearly tesa%e siDe no %atterits location on te sky)

ore'round obHects%ake a oriDon Moonsee% (arter in tedistance) Te %ind

interprets %oredistant obHects as3ider)

8/9/2019 01 Naked-eye Observations of Sun & Moon

24/46

Lunar #ases

Te Moon5s appearance under'oes are'ular cycle o( can'es, takin' rou'ly2I)8 days to co%plete)

Te 3ord %ont derives (ro% Moon ;)Te inese and sla%ic calendars in use

today are still based s*uarely on te lunarcycle, eac %ont be'innin' 3it te ne3Moon)

Te %odern 4estern calendar retains %ontsas convenient subdivisions, but tey ave noparticular lunar si'niGcance)

8/9/2019 01 Naked-eye Observations of Sun & Moon

25/46

Moon Orbits Eart

Te Moon e%its no li't o( its o3n)nstead, it sines by re=ected sunli't)

@al( o( te Moon5s sur(ace is

illu%inated by te Sun at any instant)

?ecause te Moon orbits Eart, tevisible (raction o( te lunar sunlit (ace

varies (ro% ni't to ni't) JouTube: Te #ases o( te Moon

8/9/2019 01 Naked-eye Observations of Sun & Moon

26/46

8/9/2019 01 Naked-eye Observations of Sun & Moon

27/46

8/9/2019 01 Naked-eye Observations of Sun & Moon

28/46

More rescent Moons

rescent Lunar#ase

LunarEclipseK

LunarEclipseK

8/9/2019 01 Naked-eye Observations of Sun & Moon

29/46

8/9/2019 01 Naked-eye Observations of Sun & Moon

30/46

#artial Eclipse

212 9une 6

4e see tat te Eart5s sado3on te Moon is curved)

8/9/2019 01 Naked-eye Observations of Sun & Moon

31/46

Eart5s urved Sado32$ "u'ust

Tis co%posite i%a'e uses successive picturesrecorded to trace out a lar'e part o( te u%braCs

8/9/2019 01 Naked-eye Observations of Sun & Moon

32/46

Total Eclipse

211ece%ber N": Sin'aporeans 'ater to

see lunar eclipse

8/9/2019 01 Naked-eye Observations of Sun & Moon

33/46

i+, ./0E I)11

eep 0ed oloration

urin' a total lunar eclipse, te Moon o(tenac*uires an eerie, deep red coloration)

" s%all a%ount o( sunli't is reddened byEart5s at%ospere 0aylei' scatterin'; andre(racted bent; onto te Moon5s sur(ace)

8/9/2019 01 Naked-eye Observations of Sun & Moon

34/46

Solar Eclipses

8/9/2019 01 Naked-eye Observations of Sun & Moon

35/46

8/9/2019 01 Naked-eye Observations of Sun & Moon

36/46

Total Eclipse

Te day is brie=yturned into ni't)#lanets and so%e

stars beco%evisible in tedayti%e)

Ti%e-Lapse: " Total

Solar Eclipse

2$ "u'ust, .reat 4all,ina

8/9/2019 01 Naked-eye Observations of Sun & Moon

37/46

8/9/2019 01 Naked-eye Observations of Sun & Moon

38/46

ia%ond 0in'

212 Nov1!

"s te total pase te solareclipse ca%e to an end, sunli'tstrea%in' past te ed'e o( teMoon created te =eetin'

appearance o( a 'listenin'dia%ond rin' in te sky)

Sunli't strea%in' trou''aps in te ru''ed proGle o(te lunar li%b creates tebrilliant but =eetin' ?ailyCs

ia%ondsF

8/9/2019 01 Naked-eye Observations of Sun & Moon

39/46

"nnular Eclipse

Te Moon5s orbit isnot e+actly circular)

Te Moon %ay be(ar enou' (ro%Eart tat its disk(ails to cover tedisk o( te Sunco%pletely)

0ou'ly al( o( allsolar eclipses areannular)1II2

9anuary

8/9/2019 01 Naked-eye Observations of Sun & Moon

40/46

8/9/2019 01 Naked-eye Observations of Sun & Moon

41/46

uture Eclipses

?ecause 3e kno3 te orbits o( Eartand te Moon to 'reat accuracy, 3ecan predict eclipses (ar into te

(uture)

4eblinks: N"S" Eclipse 4eb Site

Eclipse alculator Solar Eclipses in

Sin'apore

8/9/2019 01 Naked-eye Observations of Sun & Moon

42/46

T3o Eclipse Seasons

Te Moon5s orbit is sli'tly inclined to teecliptic at an an'le o( 8)2;)

n an un(avorable conG'uration, te Moonlies above or belo3 te plane o( te ecliptic)

n a (avorable conG'uration, Eart, Moon,and Sun are precisely ali'ned, and aneclipse occurs)

Tere are t3o periods, kno3n as eclipseseasons, at 3ic an eclipse can occur)

Si%ulation: Eclipses

8/9/2019 01 Naked-eye Observations of Sun & Moon

43/46

Moon5s Orbital nclination

8/9/2019 01 Naked-eye Observations of Sun & Moon

44/46

#recession o( Moon5s Orbit

Te eclipse seasons 'raduallypro'ress back3ard trou' tecalendar, occurrin' about 1I days

earlier eac year) Te 'ravitational tu' o( te Sun

causes te Moon5s orbital orientation

to can'e slo3ly 3it ti%e) "ni%ation: #recession o( Moon5s Orbit

8/9/2019 01 Naked-eye Observations of Sun & Moon

45/46

i+, ./0E I)12

Te Bisibility o( an Eclipse

" total solar eclipsecan be seen (ro%only a s%all

portion o( Eart5sdayti%e side)

" lunar eclipse issi%ultaneously

visible (ro% alllocations onEart5s ni't side)

8/9/2019 01 Naked-eye Observations of Sun & Moon

46/46

Moon5s Sado3

"nnular Solar Eclipse, 212 May 2