The Solar SystemThe Solar System

Chapter 23, Section 1Chapter 23, Section 1

The Planets: An The Planets: An OverviewOverview

Terrestrial Planet – any of the Earth-like planets: Mercury, Venus, Earth, and Mars

Jovian Planet – the Jupiter-like planets: Jupiter, Saturn, Uranus, and Neptune; these planets have relatively low densities and are huge gas giants

Size is the most obvious difference between the terrestrial and the Jovian planets

The diameter of the largest terrestrial planet, Earth, is only ¼ the diameter of the smallest Jovian planet, Neptune; it’s mass is only 1/17 that of Neptune

Density, chemical makeup, and rate of rotation are other ways in which the two groups of planets differ

The densities of the terrestrial planets average about 5 times that of water, while the Jovian planets only average about 1.5 times that of water

Planets Planets Drawn Drawn

to Scaleto Scale

The Interiors of the The Interiors of the PlanetsPlanets The substances that make up the The substances that make up the

planets are divided into 3 groups: planets are divided into 3 groups: gases, rocks, and icesgases, rocks, and ices

1.1. Gases – Hydrogen and Helium Gases – Hydrogen and Helium (melting point = -273(melting point = -273ooC)C)

2.2. Rocks – Silicate minerals and metallic Rocks – Silicate minerals and metallic iron (melting point = 700iron (melting point = 700ooC)C)

3.3. Ices – Ammonia, methane, carbon Ices – Ammonia, methane, carbon dioxide, and water (melting point = dioxide, and water (melting point = 00ooC)C)

Terrestrial planets contain mostly Terrestrial planets contain mostly rock material, while the Jovian rock material, while the Jovian planets contain the gases and ices.planets contain the gases and ices.

The Interiors of the The Interiors of the PlanetsPlanets

The Atmospheres of The Atmospheres of the Planetsthe Planets A planet’s ability to retain an atmosphere A planet’s ability to retain an atmosphere

depends on its mass and sizedepends on its mass and size Jovian planets have thick atmospheres of Jovian planets have thick atmospheres of

hydrogen, helium, methane, and hydrogen, helium, methane, and ammonia, due to their high surface ammonia, due to their high surface gravities and the ability to hold on to the gravities and the ability to hold on to the light gaseslight gases

Terrestrial planets have very small Terrestrial planets have very small atmospheres in comparison, with the atmospheres in comparison, with the atmosphere making up only a small atmosphere making up only a small portion of the planet’s massportion of the planet’s mass

The Atmospheres of The Atmospheres of the Planetsthe Planets

Formation of the Solar Formation of the Solar System – Nebular System – Nebular TheoryTheory Nebula – a cloud of dust and gas in

space These thin gaseous clouds begin to

rotate and contract, and then spin faster According to the nebular theory, the sun

and planets formed from a rotating disk of dust and gases

As the speed of rotation increased, the center of the disk began to flatten out

The matter became more concentrated in the center, eventually igniting a nuclear reaction (the sun)

Formation of the Solar Formation of the Solar System – System – PlanetesimalsPlanetesimals Planetesimals – small, irregularly

shaped bodies; formed from the collision of matter in space

As the collisions continued, the planetesimals grew larger, and began exerting their own gravity

In the inner solar system, it was so hot that only the metals and silicate materials could form

In the outer solar system, it was cool enough for the planets to attract ice and gases to add to their mass

FormatioFormation of the n of the Solar Solar System – System – Nebular Nebular TheoryTheory

AssignmentAssignment

Read Chapter 23, Section 1 (pg. 644-Read Chapter 23, Section 1 (pg. 644-648)648)

Do Section 23.1 Assessment #1-7 (pg. Do Section 23.1 Assessment #1-7 (pg. 648)648)