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Presentation by: Heather DeRoy

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Discovery of New Planet!

Planet Earth, a part of a Solar System, is apossible candidate for life

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Lets investigate the location of

planet Earth to see if it is apossible location for life to form!

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Galactic

Neighborhood

Galactic environmentimpacts habitabilityMilky Way galays

edge is a lifefavorable spot"ot near active

gamma ray so#rce"ot near galactic

center $ith highstar density and

ioni%ing radiationLoneliness in

galay is helpf#l forlife

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&he galactic neighborhood is

good' lets investigate the star it

orbits!

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Spectral Class of Star Needed for Life:

Spectral classindicates photospheric

temperat#re

()))* to +)))*Emit highfre#ency

-. radiation to trigger

atmospheric o%one

formation

Emits not so m#ch that

ioni%ation destroys life

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Spectral Class of Sun

Earth rotates aro#nd the star, the /S#n0S#n

G1 star

23,)))*

S#n is in /4abstar0 range!

5%one can form in atmosphere

6oni%ation is not deadly for life

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Low Stellar ariation"

7ll stars change l#minosityStars vary in stability'

stars that fl#ct#ate

l#minosity violently are poorcandidates for hosting life

&he S#n is relatively stable!

Solar variation is 289: over 99yearcycleSlight variations dramatically impact

Earth ;

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Now that we know theSun star is a goodcandidate tosupport life,lets look at planet Earths

position relatie to theSun!

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#abitable $one&heoretical shell aro#nd a star

$here any planet present $o#ldhave li#id $ater on its s#rface

4< range sho#ld not vary over time

Stars increase l#minosity as

they age6f this happens too #ickly

=s#permassive star>, planets

are only in $indo$ for life for

short amo#nt of time

Lo$ers time to develop life

http://upload.wikimedia.org/wikipedia/commons/9/94/Habitable_zone-en.svg

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%s &arth Located in #abitable $one"

?es!

Earth is located $ithin the epected shell of

distance in $hich li#id $ater can be on the

s#rface of the planet!

Pict#res of the planet sho$ li#id $atercovering a large portion of the Earths s#rface!

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&he relative position of Earthappears capable of s#pporting life'

so lets look at the planet itself!

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Planet Characteristics that Support Life&errestrial

Silicate rocks

@ocks not accreted

to gaseo#s o#ter

layers

Gas Giants A no life

"o s#rface

Enormo#s Gravity

Satellites are good

candidates,

ho$ever

http://en.wikipedia.org/wiki/File:Earthlike_moon_extrasolar_gas_giant.jpg

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Co'position of &arth"

Earth is a terrestrial planet, not a gasgiant

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(ass of Planets need to be )ust *ight

for Life

Lo$ MassBad ne$s for life

Lesser gravity ; diffic#lt for atmosphere

retentionSmaller planets lose energy from formation

#icklygeologically dead

7pproimately )8C Earth masses needed to s#stain

life

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(ass of &arth4igh Mass

Earth is largest by mass and density ofterrestrial bodies in the Solar System

Large eno#gh for molten core =heat engine>

Large eno#gh for atmosphere thro#gh gravityLarge eno#gh for li#id o#ter core and metal

inner core =magnetic field>

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(agnetic +ields and Life

Planets need protection from solar $ind

Solar $ind stream of charged particles

from stars consisting of electrons and

protons

Planet m#st have molten metal interior

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Does &arth have a (agnetic +ield"

?es!Earth has solid metal core $ith li#id o#ter

core, ca#sing magnetic field

Protects the Earth from solar $ind

http://en.wikipedia.org/wiki/File:Magnetosphere_rendition.jpg

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,t'osphere and Life

7tmosphere ; layer of gases that s#rro#nd amaterial body of s#fficient mass

4eld by gravity

4elps reg#late temperat#re

Protects planet from meteors and radiation

Domposition favors life =oygen and carbon

dioide>

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Does &arth have an ,t'osphere"

?es!Earths atmosphere is made #p

of "itrogen =(:>

5ygen =1)8F:>7rgon =8FC:>

Darbon ioide =8)CF):>

&his composition co#ld s#pportlife

7tmosphere absorbsHreflects

harmf#l radiation

.isible and @adio reach

http://en.wikipedia.org/wiki/File:Atmosphere_gas_proportions.svg

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Co'position of Planets

Io#r elements vital for lifeDarbon

4ydrogen

5ygen"itrogen

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Earths DompositionJ

Element oygen alone fo#nd in Earths cr#st'4o$ever, other life elements are fo#nd in atmosphere

and $ater

Make amino acids =b#ilding blocks of protein>

Domets and o#tgassing from volcanoes bro#ght theseelements

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&ectonic 7ctivity of Planet

S#pply s#rface $ith lifes#stainingmaterial

S#pply atmosphere $ith temperat#re

moderators =D51>@ecycles important chemicalsHmaterials

4elps increase environmental compleity

Earth is tectonically active!!

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&he planet Earth itself looks

hopef#l for s#pporting life'$hat abo#t its orbit and

rotationJ

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Life-Supporting .rbits

Stability is criticalEccentricity

Greater e, greater

temperat#re fl#ct#ationLiving organisms can only

$ithstand certain

fl#ct#ations

Domple organisms have greater

temperat#re sensitivity

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6s Earths 5rbit S#itableJ?es!Earths 5rbit

7lmost circ#larE K 8)1

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LifeS#pporting @otation@otation aro#nd ais at tilt

Planet sho#ld have moderate seasons

or biospheric dynamism $ill disappear

Witho#t tilt, planet $o#ld be colder

=$arm $eather co#ld not movepole$ard>

Sho#ld not be radically tilted beca#se

seasons $o#ld be etreme

Speed of @otationSho#ld be relatively #ick so daynight

cycle is not too long =temperat#re

differences if long daysHnights>

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Earths @otationJ

Earths tilt varies bet$een 198 and 1+8degrees every +9,))) years

ay is only 1+ ho#rs

Moon plays cr#cial roleModerates Earths climate by stabili%ing aial

tilt

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Earth D5-L have life! Galactic "eighborhood

7rm of Milky Way galay Star

Spectral class G1

Lo$ stellar variation

istance from Star

Earth is located in 4abitable

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"o$ $e need a closer look8