The Solar SystemThe Solar System

Chapter 23.1Chapter 23.1

The Solar SystemThe Solar System 99.85% of the mass of our solar system is 99.85% of the mass of our solar system is

contained in the Suncontained in the Sun 8 planets:8 planets:

MMercuryercury VVenusenus EEartharth MMarsars JJupiterupiter SSaturnaturn UUranusranus NNeptuneeptune ((PPluto)luto)

The PlanetsThe Planets

All planets travel in an elliptical orbit and All planets travel in an elliptical orbit and travel in the same direction around the travel in the same direction around the SunSun

The orbital planes of seven planets lie The orbital planes of seven planets lie within 3 degrees of the plane of the Sun’s within 3 degrees of the plane of the Sun’s equatorequatorMercury’s orbit is inclined 7 degreesMercury’s orbit is inclined 7 degreesPluto’s orbit is inclined 17 degreesPluto’s orbit is inclined 17 degrees

The Planets: An OverviewThe Planets: An Overview

Terrestrial (“Earth-like”) planets:Terrestrial (“Earth-like”) planets: MercuryMercury VenusVenus EarthEarth MarsMars

Jovian (“Jupiter-like”):Jovian (“Jupiter-like”): JupiterJupiter SaturnSaturn UranusUranus NeptuneNeptune

Terrestrial vs. JovianTerrestrial vs. Jovian

Which group of Which group of planets are bigger?planets are bigger?

PlanetPlanet Diameter (km)Diameter (km)

MercuryMercury 4,8784,878

VenusVenus 12,10412,104

EarthEarth 12,75612,756

MarsMars 6,7946,794

JupiterJupiter 143,884143,884

SaturnSaturn 120,536120,536

UranusUranus 51,11851,118

NeptuneNeptune 50,53050,530

Terrestrial vs. JovianTerrestrial vs. Jovian

Which group of Which group of planets has a faster planets has a faster period of rotation?period of rotation?

PlanetPlanet Period of Period of RotationRotation

MercuryMercury 59 days59 days

VenusVenus 244 days244 days

EarthEarth 23 hrs 56 mins23 hrs 56 mins

MarsMars 24 hrs 37 mins24 hrs 37 mins

JupiterJupiter 9 hrs 50 mins9 hrs 50 mins

SaturnSaturn 10 hrs 14 mins10 hrs 14 mins

UranusUranus 17 hrs 14 mins17 hrs 14 mins

NeptuneNeptune 16 hrs 3 mins16 hrs 3 mins

Terrestrial vs. JovianTerrestrial vs. Jovian

Which group of Which group of planets has a greater planets has a greater density?density?

PlanetPlanet Density Density (g/cm(g/cm33))

MercuryMercury 5.45.4

VenusVenus 5.25.2

EarthEarth 5.55.5

MarsMars 3.93.9

JupiterJupiter 1.31.3

SaturnSaturn 0.70.7

UranusUranus 1.21.2

NeptuneNeptune 1.71.7

Terrestrial vs. JovianTerrestrial vs. Jovian

Terrestrial planets consist mostly of rocky Terrestrial planets consist mostly of rocky and metallic substancesand metallic substances

Jovian planets consist of large amounts of Jovian planets consist of large amounts of gases (hydrogen and helium) and ices gases (hydrogen and helium) and ices (mostly water, ammonia, and methane)(mostly water, ammonia, and methane)

General TrendsGeneral Trends

What happens to the What happens to the planets’ period of planets’ period of revolution as they get revolution as they get farther away from the farther away from the Sun?Sun?

PlanetPlanet Period of Period of RevolutionRevolution

MercuryMercury 88 days88 days

VenusVenus 225 days225 days

EarthEarth 365 days365 days

MarsMars 687 days687 days

JupiterJupiter 12 years12 years

SaturnSaturn 29.5 years29.5 years

UranusUranus 84 years84 years

NeptuneNeptune 165 years165 years

General TrendsGeneral Trends

What happens to the What happens to the planets’ orbital planets’ orbital velocity as they get velocity as they get farther away from the farther away from the Sun?Sun?

PlanetPlanet Orbital Orbital Velocity (km/s)Velocity (km/s)

MercuryMercury 47.547.5

VenusVenus 35.035.0

EarthEarth 29.829.8

MarsMars 24.124.1

JupiterJupiter 13.113.1

SaturnSaturn 9.69.6

UranusUranus 6.86.8

NeptuneNeptune 5.35.3

Atmosphere of the PlanetsAtmosphere of the Planets Planet’s ability to retain an Planet’s ability to retain an

atmosphere depends on its mass atmosphere depends on its mass and temperatureand temperature

A gas molecule can escape from a A gas molecule can escape from a planet if it reaches a speed known planet if it reaches a speed known as the as the escape velocityescape velocity

A planet that has a lot of mass A planet that has a lot of mass (and therefore gravity) will hold on (and therefore gravity) will hold on to the gas moleculesto the gas molecules

A planet that is cold will have slow A planet that is cold will have slow moving gas moleculesmoving gas molecules

Nebular TheoryNebular Theory

A cloud of dust and gas in A cloud of dust and gas in space is called a space is called a nebulanebula

A nebula is made of 92% A nebula is made of 92% hydrogen, 7% helium, and hydrogen, 7% helium, and less than 1% heavier less than 1% heavier elementselements

Nebular TheoryNebular Theory: the Sun and : the Sun and planets formed from a rotating planets formed from a rotating disk of dust and gasesdisk of dust and gases

PlanetesimalsPlanetesimals

Solid bits of matter Solid bits of matter began to collide and began to collide and clump together through clump together through a process of a process of accretionaccretion

These small, irregularly These small, irregularly shaped bodies are shaped bodies are called called planetesimalsplanetesimals

Formation of Our Solar SystemFormation of Our Solar System

Terrestrial planets are dense and solid Terrestrial planets are dense and solid because only metals and minerals were because only metals and minerals were solid so close to the Sun during formationsolid so close to the Sun during formation

Jovian planets became gas giants Jovian planets became gas giants because they formed from the because they formed from the accumulation of large quantities of ice and accumulation of large quantities of ice and grew large enough to capture light gasesgrew large enough to capture light gases