Chapter 23.1The Solar System

• Our solar system consists of 8 planets

• All planets travel in a elliptical orbit

Terrestrial planets

• Earth like, small and rocky– Mercury– Venus– Earth– Mars

Jovian planets

• Jupiter like, huge gas giants– Jupiter – Saturn– Uranus– Neptune

• Pluto fits into neither category

• Size is the main difference between terrestrial and Jovian planets– Earth’s mass is only

1/17 as great as Neptune’s

• Density, chemical makeup, and rate of rotation are different– Density of

terrestrial planets average about 5 times the density of water

Planet Sizes

The Interiors of the Planets• Substances that make up

the planet are divided into 3 groups– Gases– Rock– Ice: Ex. ammonia,

methane, carbon dioxide, and water

• Terrestrial planets are mostly rocky and have metallic substances

• Jovian planets have large amounts of gases and ices

The Atmosphere of the Planets

• Jovian planets have thick atmospheres of helium, methane, and ammonia

• A planet’s ability to retain an atmosphere depends on its mass and temperature– Jovian planets have

greater surface gravities

Formation of the Solar System• Nebular Theory

– the sun and the planets formed from a rotating disk of dust and gases– As the speed of

rotation increased, the center began to flatten out causing matter to become more concentrated in the center, which is the sun

• Bits of matter began to clump together, called accretion.

• Colliding matter formed small, irregularly shaped bodies called planetesimals.– In the inner solar system,

close to the sun, temperatures were high

• Only metal and silicate minerals could form.

– In the outer solar system, it was cold enough for ices to form.