Formation of the Solar System

Formation of Solar System

~ 4.6 billion years ago huge cloud of gas and dust
started collapsing gravitationally

• As it collapsed it spun faster (conservation of
angular momentum)

• No (or little) spin in the perpendicular plane

• Local clusters of dust and gas condensed - protosun
formed first

• As material cooled, it condensed but never stopped
rotating (rotates still since there’s nothing to stop
it)

• Cores probably formed first, then attracted
neighboring materials to form:  planetesimal,
protoplanet

• Probably not a unique system - there is increasing
evidence for the existence of many other planetary
systems

• Still an evolving theory

• All planets revoluve around the sun in the same
direction, but 3 have different directions of rotation
(relative to the rest and to the direction of solar
system motion) - Uranus, Venus, Pluto


The Terrestrial Planets:  Mercury, Venus, Earth, and
Mars

Relative Characteristics:

Planet   Distance        Period          Radius          Mass

Mercury  0.4             0.24            0.38            0.055
Venus    0.7             0.62            0.95            0.82
Earth     1               1               1               1
Mars     1.5             1.88            0.53            0.11

The Jovian Planets (gas giants)

Jupiter  5.2             11.9            11.2            318
Saturn   9.5             29.5             9.3             95
Uranus   19                84             4.0            14.6
Neptune  30               165             3.9            17.2