Astronomy Exam #2 (1. Formation and Structure of the Solar System)

Formation and Structure of the Solar System

Solar Nebula

large cloud of gas and dust that formed the solar system

Nebular Theory

solar system formed from solar nebula

gravity caused cloud (solar nebula) to collapse, forming sun and rotating disk of material around it

as material accumulated, collisions and gravitational interactions helped build planets and smaller bodies

conservation of energy

as nebular cloud collapsed under gravity, gravitational potential energy was converted into other forms of energy, including thermal energy

conversion caused collapsing cloud to heat up

central region became very hot and dense, allowing nuclear fusion to begin in the sun

conservation of angular momentum

original cloud had angular momentum because it was rotating

as cloud contracted, conservation of angular momentum caused its rotation rate to increase

collisions and interactions among particles helped flatten rotating clouds into disk

planets formed from this disk, helping explain why most planets orbit the sun in approximately same plane and direction

conservation of energy vs conservation of angular momentum

conservation of energy = helps explain why collapsing nebula heated up

conservation of angular momentum = helps explain collapsing nebula’s faster rotation and disk like structure

frost line

approximate distance from young sun beyond which water and other volatile compounds condense into ice

inside frost line

rocky and metallic materials were the main solid building blocks

beyond the frost line

ice could also accumulate, allowing larger planetary cores to form

Terrestrial planet formation

Mercury, Venus, Earth, and Mars

relatively small, rocky, dense planets that formed in the warmer inner solar system

Jovian planet formation

Jupiter, Saturn, Uranus, and Neptune

These are much larger planets that formed in the colder outer solar system

availability of ice beyond the frost line helped outer planets build larger cores and accumulate more material

Planetary migration

Plantes can change their orbits through gravitational interactions with the surrounding disk and other bodies

Planetary migration helps explain how giant planets can end up close to their stars

Hot Jupiters

giant planets that orbit very close to their host stars

their existence challenged the simplest version of the solar system formation model because giant planets were expected to form primarily in colder regions

Planet ordering moving outward from the sun

Mercury → Venus → Earth → Mars → Jupiter → Saturn → Uranus → Neptune

Pluto = Dwarf planet