introduction to solar system astronomy

8/9/2019 Introduction to Solar System Astronomy

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Introduction to Sola

http://www.ma

S

ystem Astronomy

cusmoon2022.org/


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Solar SystWednesday,

m SurveyOctober 21


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K ey Co

(1) The terrestrial planetsrock and metal.

(2) The Jovian planets are

hydrogen and helium.(3) Moons (a.k.a. satellites

moons are large.

(4) Asteroids, meteoroids,objects orbit the Sun.

(5) Collision between obje

cause impact craters.

n

cepts

are made primarily of

made primarily of

orbit the planets; some

omets, and K uiper Belt

ts in the Solar System


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F amily portrait o

Mercury, Venus, EartUranus, Neptune,

My Very Excellent Mo

(Extra Ch

the Solar System:

, Mars, Jupiter, Saturn,(Eris, Ceres, Pluto):

her Just Served Us Nine

ese Pizzas).


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T he Sola

List of In

Ingredient

SunJupiter other planetseverything else

System:

redients

Percent of total mass

99.8%0.1%0.05%0.05%


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The Sun dominate s the Solar System


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Jupiter domin t es the planets


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O bject1) Sun

2) Jupiter 3) Saturn4) Neptune

5) Uranus6) Earth7) Venus

8) Mars9) Mercury

Mass330,000

3209517

151.0

0.82

0.110.055

111

111

111

O bject

) Ganymede1) Titan

) Callisto

) Io) Moon

5) Europa

6) Triton) Eris

8) Pluto

Mass

0.0250.0230.018

0.0150.0120.008

0.0040.0020.002


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A few words

The Sun is a large sphereof gas (mostly H, He

hydrogen and helium).The Sun shines because it

is hot (T = 5,800 K ).

The Sun remains hot because it is powered by fusion of hydrogento helium (H-bomb).

bout the Sun.


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(1) The terrestmade primarily o

Mercury, Venus, Earth, &

The terrestrial planets are:low in mass (< Earth masshigh in density (> 3900 kg

Water = 1000 kg/m 3

Air = 1 kg/m 3

Rock = 3000 kg/m 3

ial planets aref rock and metal.

ars.

m3).


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The mass of a planet i

Newtons version of applied to a satellite

The average density isvolume (for a sphere

The density of terrestri

than that of rock, ref extremely dense met

determined by

K eplers Third Law,natural or artificial).

mass divided byV = [4 T /3] r 3).

al planets is greater

ecting the presence of l cores.


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(2) The Jovimade primarily of h

Jupiter, Saturn, Uranus, Neptune:

The Jovian planets are:high in mass (> 14 Earth ma

low in density (< 1700 kg/m

Jovian planets are made maiof light elements like hydr and helium.

n planets aredrogen and helium.

ses)

).

nlygen


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Pluto: The O ddity (

Pluto is very low in mass(about 2000 kg/m 3). It imade of mixture of ice

ow a Dwarf Planet)

nd moderate in densitysurmised that Pluto is

nd rock.


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Spectr

The spectrum of reflecobject is made of (

Example: The spectrum omethane ice (frozen CH

, again!

ed light tells us what ant least on the surface).

Pluto is similar to that of ).


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(3) Moons (a.k.a.

the planets; somThe current moon count:

Mercury = 0

Venus = 0Earth = 1

Mars = 2

Jupiter = 63

Saturn = 61

Uranus = 27

satellites) orbit

moons are large.

Neptune = 13

Ceres = 0Pluto = 3Eris = 1

Haumea = 2Makemake = 0

Jovian planets are moon-

rich; others are not.


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T he Gia

(moons biggEarth:Jupiter:

Saturn: Neptune:

t Moons

r than Pluto)The MoonIoEuropaGanymede

CallistoTitanTriton


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Giant Moons a

The giant moons are low i

terrestrial planets.

d Dwarf Planets

density compared to the


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(4 ) Asteroids, m

andK

uiper Belt o

Asteroids: made of ro1000 km across. (Mo

between mars and Ju

teoroids, comets,

jects orbit the Sun.

k and metal, less thanst asteroids are in orbititer.)


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Meteoroids: made of r than 300 meters acroenters Earths atmosmeteor .)

ock and metal, lesss. (When a meteoroidhere, it produces a


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C omets: made of dirtyice, a few kilometers

across. (Comets havetails of gas and dustwhen they come near

the Sun.)


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K uiper Beltobjects:made of ice,hundreds of kilometers

across. (The K uiper Belt lies

beyond theorbit of

Neptune.)


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(5) Collisions bet

Solar System caThe orbits of the planets are

not collide with each othe

Smaller objects, though, freand moons.

een objects in the

se impact craters.well separated; planets do.

uently collide with planets


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When a meteoroid,asteroid, or comet

strikes a terrestrial planet (or moon), it blasts out an impact

crater.The Moon is heavily

cratered; Earth has

few craters, due toerosion andgeological activity.


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The current state

contains clu

Terrestrial planets are clo

a = 0.4 A.U.

Jovian planets are far fro

a = 5 A.U.

Just coincidence, or an im

f the Solar System

s to its history.

e to Sun

1.5 A. U.

Sun

30 A. U.

ortant clue?


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All planets revolve in the sam

direction (counterclockwise,seen from above the North

Just coincidence, or an import

ole).

nt clue?


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Most (but not all) planets r(counterclockwise, seen

Uranus and Pluto are sidedown.

Could this also be a clue?

otate in the same directionrom above the North Pole).

ays, Venus is upside-


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F ew closin

1) How do we know the mVenus?

2) Which one is denser: M3) Which one is denser: M

4) Can density of a planetwater?

5) What are the seasons on

questions:

ss of Mars? Mass of

on or Earth?on or Pluto?

e lower than density of

Uranus?

introduction to solar system astronomy

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