19-10-27 1 Novice Astronomy Classes Peterborough Astronomical Association The Sun, Earth & Moon System The Sun, Earth & Moon comprise our immediate part of the universe. Their relative motions give us day & night, the seasons, the phases of the moon, eclipses & tides. It is a wonderful dance, choreographed by Mother Nature and Newtonian physics. The Sun, Earth & Moon System Relative Sizes of the Sun, Earth & Moon Relative sizes and distances apart are to scale. Earth Moon The sun is 334,000 times more massive than earth. The earth & sun are 150 million kilometers apart. 150 million kilometers = 1 Astronomical Unit (AU) The sun’s light takes 8½ minutes to reach earth. A large pumpkin & a small pea separated by the length of a football field. This picture is to scale. Earth’s Rotation & its Orbit of the Sun Day & Night. Sun Rises in East, Sets in West. Circular orbit in 365 days. Earth’s tilt is 23.4° to orbital plane.
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NoviceAstronomyClassesPeterboroughAstronomicalAssociation
TheSun,Earth&MoonSystemTheSun,Earth&Mooncompriseourimmediatepartoftheuniverse. Theirrelativemotionsgiveusday&night,theseasons,thephasesofthemoon,eclipses&tides. Itisawonderfuldance,choreographedbyMotherNatureandNewtonianphysics.
TheSun,Earth&MoonSystem
RelativeSizesoftheSun,Earth&Moon
Relativesizesanddistancesapartaretoscale.
Earth Moon
Thesunis334,000timesmoremassivethanearth.
Theearth&sunare150millionkilometersapart. 150millionkilometers=1AstronomicalUnit(AU)
Thesun’slighttakes8½minutestoreachearth.
Alargepumpkin&asmallpeaseparatedbythelengthofafootballfield.
Thispictureistoscale.
Earth’sRotation&itsOrbitoftheSun
Day&Night.SunRisesinEast, SetsinWest.
Circularorbit in365days.
Earth’stiltis23.4° toorbitalplane.
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HowObliquitycausestheSeasonsEarth’stilt(obliquity)is23.4°
Obliquitycausestheseasons
Angleofincidenceismaincauseofsummerwarmth&wintercold(2.5Xhigherinsummer)
Lengthofdayissecondarycause
Closenesstosundoesnotchangesignificantly
Stability:Overtime,theobliquityhaschanged:22.0°to24.5°
AnnualDaylightVariations
AtSummerSolstice AtWinterSolstice
AttheSpring&FallEquinoxes InPeterborough(10hrsvs16hrs)
�Shadowsmovefromrighttoleft�
OrbitoftheMoonaroundtheEarth
Lunarmonth=28days Distancevariesfrom362,000kmto405,000km
TheMoonorbitstheEarth&rotatesonitsownaxisonceeverylunarmonth
PhasesoftheMoon
CCWinfigure.
DarksidevsFarside
OnceinaBlueMoon
Hourlatereachday
TracktheMoon’smonthlycycleat http://sciencenetlinks.com/tools/lunar-cycle-1-calendar/
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TidesandotherFunkyStuff
BayofFundy: 16metertides 160Btonnesofseawater
LongerDays: 2ms/100yrs In1Myrsnoleapyear 6hourdays
MoonRetreating: 1.5”/year 4.5Byearsago>15Xcloser
Nottoscale!
ProfileofaLunarEclipseEarthbetweenSun&Moon
MooninEarth’s‘shadow’
Threeforms: Total,PenumbralorPartial
VisibleoverwideareaofEarth&lasts~5hours
OccursonlyduringafullMoon.
TheMooninTotalEclipse
TotalLunareclipseinPeterborough,January20/21,2019 PhotobyPAAmemberRickStankiewicz
Asthelunareclipseprogressescolourschangefromdeepbrowns&darkgraystoshadesofbrilliantredandbrightorange
ThenexttotallunareclipsevisibleinPtbowillbeMay15,2022
Eyeprotectionnotrequiredtoviewalunareclipse
ProfileofaSolarEclipse
MoonbetweenSun&Earth.OccursonlyatNewMoonphase
Moon’sshadowonEarthisverysmall,diameter<200km
Totaleclipselastsshorttime,<10minutes
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TotalEclipse
PartialEclipse
AnnularEclipse
TheDifferentFormsofSolarEclipse
TotaleclipseshowsSun’scorona.
Annulareclipseshowsaringoffire.
PartialeclipseshowsonlyapartoftheSun’sglobeblockedbytheMoon.
Eyeprotectionisrequiredtoviewasolareclipse.
ImagesofTotalSolarEclipses
PhenomenaofaTotalSolarEclipse
TotalSolarEclipsewithSpectacularCorona
Itisworththetriptoseeatleastoneoftheseinyourlifetime!
Duringtheeclipse,birdsdon’tchirpandbeesstopflying.
TheNextNorthAmericanTotalEclipseoftheSunis…
…inOurBackyard!
April8,2024�…NiagaraFalls,PrinceEdwardCounty,Kingston,Cornwall…
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