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Lecture 2

Astronomy 1021 Lecture Notes - Lecture 2: Dendrochronology


Department
Astronomy
Course Code
ASTR 1021
Professor
Robert Cockcroft
Lecture
2

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Lecture2:Chapters1+2
September18
th
,2018
OurSolarSystem
Eightplanets(andPluto)
Jupiter
Saturn
Uranus
Neptune
Earth
Venus
Mars
Mercury
Pluto
StarSizes
Examplesofstarsbiggerthanthesunare
Sirius,Pollux,andArcturus
Someofthebiggestsunsinclude
Rigel,Aldebaran,Betelgeuse,andAntares
SmallSolarSystemObjects
DwarfPlanets
Eris
Pluto
Haumea
Makemake
Ceres
Othersmallobjects
Moon
Triton
2002TC
302
Charon
Quaoar
Sedna
Orcus
Varuna
2002UX
25
Ixion
2002AW
197
1996TL
66
Chaos
1996TO
66
HowFarApartAreSolarSystem
Objects?
TheEarthandtheMoonare
385,000km(3.85x10
5
km)

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LightYear
Alightyearisthedistancethatlightcantravel
in1year
Distance=SpeedxTime
=3x10
8
m/sx1year
=3x10
8
m/sx365dx24hrx60minx60sec
=3x10
8
m/sx3.15x10
7
s
=9.5x10
15
m
Lightyearsalsogivesyouthetraveltimeit
tooklighttocrossthatdistance
1.5lightseconds;MoonEarth
8lightminutes;SunEarth
4.5lighthours;PlutoEarth
4.2lightyears;AlphaCentauriSun
12x10
5
lightyears;MilkyWaydiameter
2.5x10
6
lightyears;AndromedaSun
9.1x10
10
lightyears;diameterofobservableuniverse
CosmicCalendar
Wealsohavetolookatthetimeoftheuniverseaswellasthesize
Thecosmiccalendarcompressesthelifeoftheuniverseintoasingleyear
TheBigBanghappenedinthefirstsecondofJanuary1standeverythinghumanshaveeverdoneisinthelast10
secondsofDecember31st
Eachsecondis500years
Humansdebutedaround10:30p.m.onDecember31st
At11:46,humanstamedfire
At11:59:20,humansbegantodomesticateplantsandanimals
At11:59:55,agriculturalcivilizationsappear
TheUniverseis13.8billionyearsold
Howdowemeasuretimescales?
Dendrochronology
Annualglacierlayers
Radiometricdating
Longertimescales
Universe’soldestobject
DetermineUniverse’sexpansiontime
Abundancesofelements
Useobservations(spectra)andsimulations/models
“Spaceship”Earth
Motionoftheearthrotating
Motionoftheeartharoundthesun
Motionofthegalaxy
Wearenotstationary
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