Astronomy Part 2Astronomy Part 2Earth in the UniverseEarth in the UniverseMotions of Earth, Moon, and Motions of Earth, Moon, and SunSun

Earth in the UniverseEarth in the Universe

Eccentricity and EllipseEccentricity and Ellipse An An ellipseellipse is an oval shape. is an oval shape. Earth’s Earth’s orbitorbit around the sun is an around the sun is an

ellipse.ellipse. Within an ellipse, there are two Within an ellipse, there are two

fixedfixed points called points called focifoci.. In In ourour solar system, the solar system, the sunsun is is

ALWAYSALWAYS ONE of those foci. ONE of those foci.

You can make an ellipse with 2 tacks and a string. The tacks are the “foci”, and if you put them further apart, the ellipse is more “eccentric” (one tack makes a circle).

An ellipse is an example of a “conic section”. Circles and hyperbolas are others. All are possible forms for orbits.

Eccentricity and Eccentricity and EllipsesEllipses The The degreedegree of of flatnessflatness or or

“ovalness” of an ellipse is “ovalness” of an ellipse is measured by measured by eccentricityeccentricity..

This formula is on page This formula is on page 11 of your ESRT!of your ESRT!

Pg 1 ESRTPg 1 ESRT

Eccentricity and EllipseEccentricity and Ellipse The more The more ovaloval the orbit is, the the orbit is, the

more more eccentriceccentric it is, or the higher it is, or the higher the eccentricity.the eccentricity.

Increasing Eccentricity

Eccentricity and EllipseEccentricity and Ellipse Calculating Eccentricity:Calculating Eccentricity:

X X

Major Axis

Foci 1 Foci 2

Eccentricity and EllipseEccentricity and Ellipse

Calculating Eccentricity:Calculating Eccentricity: When you measure those 2 When you measure those 2

distances and calculate them, you distances and calculate them, you will will NEVERNEVER get higher than get higher than 11!!!!

The closer to 1 you are the The closer to 1 you are the MOREMORE oval or eccentric the orbit.oval or eccentric the orbit.

The closer to 0 you are the The closer to 0 you are the LESSLESS oval or eccentric the orbit.oval or eccentric the orbit.

Gravitational ForceGravitational Force The The closercloser 2 objects are to each other, 2 objects are to each other,

the the greatergreater the the gravitationalgravitational pull pull between them.between them.

Therefore, during the Therefore, during the perihelionperihelion – when – when Earth is Earth is closercloser to the sun, there is a to the sun, there is a greatergreater gravitationalgravitational pull between it and pull between it and the sun.the sun.

This makes the Earth This makes the Earth speed upspeed up a bit in a bit in its its orbitorbit around the sun during that time. around the sun during that time.

Gravitational ForceGravitational Force

Perihelion Aphelion

Page 15 in ESRT – Turn there now!

The Big Bang TheoryThe Big Bang Theory The The universeuniverse started with a started with a

concentrated area of concentrated area of mattermatter and and energy.energy.

15-2015-20 billion years ago. billion years ago. Then, it Then, it explodedexploded and has been and has been

expandingexpanding ever since. ever since. FasterFaster moving stuff traveled moving stuff traveled fartherfarther..

The Big Bang TheoryThe Big Bang Theory

Matter began to Matter began to clumpclump together forming together forming starsstars and and galaxiesgalaxies..

The universe continued to The universe continued to expand and is still expand and is still expandingexpanding today. today.

The Big Bang TheoryThe Big Bang Theory What proof do we have that the What proof do we have that the

big bang did happen?big bang did happen? 1. Recently, scientists have found 1. Recently, scientists have found

long-wavelong-wave radiation coming from radiation coming from all all directionsdirections in the universe. This in the universe. This is the is the energyenergy that was created that was created from the Big Bang.from the Big Bang.

2. The universe is still 2. The universe is still expandingexpanding..

Universe ExpansionUniverse Expansion How do we know the universe is How do we know the universe is

expanding?expanding? Pg. Pg. 1414 in the ESRT shows the in the ESRT shows the

electromagneticelectromagnetic spectrum. spectrum. Notice that in the Notice that in the visiblevisible

spectrum there are all the colors spectrum there are all the colors of the of the rainbowrainbow..

Pg. 14 ESRTPg. 14 ESRT

Shortwave

Longwave

Universe ExpansionUniverse Expansion When looking at the visible spectrum When looking at the visible spectrum

wavelengthswavelengths are shifted either to the are shifted either to the blueblue end (shorter wave) or the end (shorter wave) or the redred end end (longer wave).(longer wave).

This shift in wavelengths is called the This shift in wavelengths is called the Doppler EffectDoppler Effect..

If they are shifted towards If they are shifted towards redred, they , they are moving are moving awayaway from you. from you.

If they are shifted toward If they are shifted toward blueblue, they , they are coming are coming towardstowards you. you.

Universe ExpansionUniverse Expansion

When scientists look at When scientists look at the universe, they see a the universe, they see a red shiftred shift. This proves it . This proves it is moving is moving awayaway from us, from us, thus, expanding!thus, expanding!

Red ShiftLight from galaxies moving away

Notice the shift to the red end

Blue ShiftLight from galaxies moving toward us

Notice the shift to the blue end

GalaxiesGalaxies The basic unit of matter in the The basic unit of matter in the

universe is a universe is a galaxygalaxy.. A galaxy is a collection of billions A galaxy is a collection of billions

of of starsstars and and gasgas and and dustdust.. Our solar system is part of the Our solar system is part of the

Milky Way GalaxyMilky Way Galaxy.. The Milky Way is a The Milky Way is a spiral-shapedspiral-shaped

galaxy.galaxy.

StarsStars A star is usually a large ball of A star is usually a large ball of gasgas

held together by held together by gravitygravity. . Produce tremendous amounts of Produce tremendous amounts of

energyenergy and they and they shineshine.. Energy is produced by Energy is produced by nuclear nuclear

fusionfusion – combination of – combination of nucleinuclei of of smaller elements to form nuclei of smaller elements to form nuclei of larger elements.larger elements.

StarsStars Stars have different:Stars have different: SizeSize CompositionComposition TemperatureTemperature ColorColor MassMass BrightnessBrightness

StarsStars SIZE – 5 main categoriesSIZE – 5 main categories:: 1. Medium sized1. Medium sized 2. Giants2. Giants 3. Supergiants (Largest)3. Supergiants (Largest) 4. White Dwarfs4. White Dwarfs 5. Neutron Stars (smallest)5. Neutron Stars (smallest)

StarsStars COMPOSITIONCOMPOSITION Mostly made up of Mostly made up of hydrogenhydrogen (60- (60-

80%)80%) Most of the rest is Most of the rest is heliumhelium.. About About 1%1% of other elements. of other elements. Determined by looking at the Determined by looking at the

colorcolor of the star. of the star.

StarsStars TEMPERATURETEMPERATURE ColorColor also indicates also indicates

temperaturetemperature hottesthottest surface surface

50,000 °C50,000 °C coolestcoolest -3000°C -3000°C BlueBlue are are hottesthottest

stars.stars. RedRed are are coolestcoolest

stars.stars.

Blue

White

Yellow

Red 3,000 ºC

5,000 °C

6,000 °C

10,000 °C

35,000 °C

Red-Orange

StarsStars BRIGHTNESSBRIGHTNESS A measure of a stars brightness is A measure of a stars brightness is

its its magnitudemagnitude.. Apparent magnitudeApparent magnitude is how bright is how bright

it looks from Earth.it looks from Earth. Absolute magnitudeAbsolute magnitude is how bright is how bright

it really is.it really is.

StarsStars Hertzsprung-Russell DiagramHertzsprung-Russell Diagram:: Found that as Found that as temperaturetemperature increased, increased,

so did so did absolute magnitude.absolute magnitude. 90%90% of stars followed this pattern of stars followed this pattern Called Called main sequencemain sequence stars stars Other Other 10%10% were once main sequence were once main sequence

stars but have stars but have changedchanged over time. over time.

White DwarfsAbs

olut

e M

agni

tude

50000

Supergiants

GiantsMain sequence

20000 10000 6600 6000 5000 3000

STAR EVOLUTION

The good news!! This is all for free on pg. 15 of the ESRT!

Our Solar SystemOur Solar System The The solar systemsolar system

is the is the sunsun and all and all objects that objects that orbitorbit the sun under its the sun under its gravitationalgravitational influence.influence.

Our solar system Our solar system has 1 sun and 8 has 1 sun and 8 planetsplanets..

Our Solar SystemOur Solar System The SunThe Sun An average star – An average star – Main Main

SequenceSequence Over 1 Over 1 millionmillion Earth’s would fit Earth’s would fit

inside.inside. 1/4 the 1/4 the densitydensity of the Earth. of the Earth. Made of 4 Made of 4 layerslayers..

Putting things into Putting things into perspective…perspective…

Putting things into Putting things into perspective…perspective…

Putting things into Putting things into perspective…perspective…

Putting things into Putting things into perspective…perspective…

Putting things into Putting things into perspective…perspective…

Solar Prominence

Remember - a lot of information about our solar system is free of charge on page 15 of your ESRT!!!

Motions of Earth, Motions of Earth, Sun, and MoonSun, and Moon

Models of Apparent Models of Apparent MotionMotion Remember, apparent motions of Remember, apparent motions of

celestial objects mean these celestial objects mean these objects objects appearappear to move, but really, to move, but really, it’s it’s EarthEarth that is moving. that is moving.

There have been 2 main models to There have been 2 main models to explain these explain these apparentapparent motions. motions.

1. 1. Geocentric ModelGeocentric Model 2. 2. Heliocentric ModelHeliocentric Model

Models of Apparent Models of Apparent MotionMotion Geocentric Model:Geocentric Model: EarlyEarly cultures cultures

believed this one.believed this one. It says the It says the EarthEarth

is the is the centercenter of of everything and all everything and all objects move objects move around it.around it.

Geo = EarthGeo = Earth

Models of Apparent Models of Apparent MotionMotion Heliocentric Model:Heliocentric Model: Model that is used and Model that is used and believedbelieved

today.today. It says the It says the sunsun is the is the centercenter of our of our

solar system and everything solar system and everything moves around it.moves around it.

Helio = sunHelio = sun

Earth’s MotionsEarth’s Motions We know that the Earth We know that the Earth

rotatesrotates.. However, However, HOWHOW do we do we

know this for sure?know this for sure? 1. 1. The Focault The Focault

PendulumPendulum The path of the The path of the

pendulum changes in a pendulum changes in a predictable way predictable way throughout the day.throughout the day.

2. 2. The Coriolis EffectThe Coriolis Effect All particles on Earth, All particles on Earth,

including wind, are including wind, are deflected or curved from deflected or curved from their original path.their original path.

The Motions of the The Motions of the MoonMoon Revolution – Counter clockwise, 1

revolution takes 27 1/3 days. Rotation - Counter clockwise, 1

rotation takes 27 1/3 days. Always see the same side of the

moon. Phases of Moon- 29½ days long.

The Motions of the The Motions of the MoonMoon Why are there an extra 2 1/6

days? Moon has to revolve for 2

more days to get back to the new moon phase.

This occurs because the Earth is revolving around the Sun.

Phases of the MoonPhases of the Moon Caused by the Caused by the

positionspositions of the of the Earth, Moon, and Earth, Moon, and sun.sun.

They They repeatrepeat because the because the moon orbits the moon orbits the Earth.Earth.

Phases of the MoonPhases of the Moon New MoonNew Moon Waxing CrescentWaxing Crescent First QuarterFirst Quarter Waxing GibbousWaxing Gibbous Full MoonFull Moon Waning GibbousWaning Gibbous Last QuarterLast Quarter Waning CrescentWaning Crescent Moon Phase CalculaMoon Phase Calcula

tortor

New Moon

Waxing Cresent

First Quarter

Waxing Gibbous

Full Moon

Waning Gibbous

Last Quarter

Waning Cresent

EclipsesEclipses 2 types of eclipses:2 types of eclipses: 1. 1. Lunar eclipseLunar eclipse – –

eclipse of the eclipse of the moon. moon.

Earth casts a Earth casts a shadowshadow on the on the moon during the moon during the FULL MOONFULL MOON phase. phase.

Umbra

Penumbra

Slide 25 Table 3-1, p. 31

EclipsesEclipses 2. 2. Solar EclipseSolar Eclipse:: Can only happen during a Can only happen during a NEW NEW

MOONMOON phase. phase. In rare cases the moon in this In rare cases the moon in this

phase can phase can block outblock out the sun, the sun, casting a casting a shadowshadow onto onto EarthEarth, , which causes a solar eclipse.which causes a solar eclipse.

Total Solar Eclipse

Partial Solar Eclipse

Slide 39 Table 3-2, p. 35

NASA Eclipse Web Page

Slide 29 Fig. 3-9a, p. 33

Slide 30 Fig. 3-9b, p. 33

Slide 31 Fig. 3-9c, p. 33

Slide 32 Fig. 3-9d, p. 33

Slide 33 Fig. 3-9e, p. 33

TidesTides

TidesTides The The gravitationgravitation between the Earth, between the Earth,

Moon, and Sun results in a Moon, and Sun results in a cycliccyclic rise rise and fall of ocean waters on Earth.and fall of ocean waters on Earth.

These are called These are called tidestides.. A bulge of water is a A bulge of water is a high tidehigh tide and and

occurs when the gravitational pull of occurs when the gravitational pull of the moon is the the moon is the greatestgreatest..

This will occur on the side This will occur on the side facingfacing the the moon, and on the exact moon, and on the exact oppositeopposite side. side.

TidesTides On the other 2 On the other 2

sides, there will sides, there will be a be a low tidelow tide..

This is where the This is where the gravitational pull gravitational pull of the moon is of the moon is the the leastleast..

TidesTides Spring TideSpring Tide – every new and full moon – every new and full moon

phase the Sun, Earth, and Moon are in a phase the Sun, Earth, and Moon are in a strait line.strait line.

This causes even This causes even higherhigher high tides. high tides. Neap TideNeap Tide – During the first and third – During the first and third

quarter moon phases, the Sun, Earth, quarter moon phases, the Sun, Earth, and Moon are at a right angle to each and Moon are at a right angle to each other.other.

This causes even This causes even lowerlower low tides. low tides.