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Geology 110


    SOLAR SYSTEM


SOLAR SYSTEM: LEARNING OBJECTIVES

 RELATED WEB SITES

 

  1. http://seds.lpl.arizona.edu/nineplanets/nineplanets/nineplanets.html

ORIGIN

 Many ideas for the origin of the solar system. Most widely accepted scientific theory is as follows:

 A nebula of dust and debris in space contracts by gravity into Sun and the planets. Asteroid belt the result of planet that never formed or one that was destroyed by collision.

 SUN

 The Sun is a star, separated from other stars by great distances.
The planets revolve around the Sun.
The Sun comprises most of the mass of the solar system.
The Sun shines from internal fusion reactions.

 PLANETS

 Planets shine due to reflected light NOT internal fusion.
Planets REVOLVE around the Sun and ROTATE on their axis.

 Order of planets from the Sun:

 Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, Pluto

 INNER PLANETS

 Mercury, Venus, Earth, Mars

 Also called terrestrial planets.
Small in size, composed of rocky material.
Few if any moons, spin slowly on their axis.

 OUTER PLANETS

 Jupiter, Saturn, Uranus, Neptune

 Also called the gas giants.
Large in size, composed of gas and although large much less dense than Earth.
Lots of moons, some rings, spin rapidly on their axis.

 MERCURY

 Closest planet to the Sun, rotates slowly [1 Mercury day = 59 Earth days].
Revolves around the Sun every 90 days.
Only a trace of an atmosphere. Sunlit side VERY hot [3000 C], dark side cold.
Dense rocky planet with some signs of volcanism, surface is pock-marked with craters.

 VENUS

 Spins slowly in opposite direction from all other planets [1 Venus day = 243 Earth days].
Revolves around Sun every 255 days and shows phases much as the moon.
Similar to Earth in size and density.
Atmosphere VERY thick and dense, composed of carbon dioxide with sulfuric acid clouds.
VERY hot, surface estimated to be about 4000 C, will melt lead.
Topography of Venus is similar to that of Earth’s suggesting that Venus has had a complex geologic history.

 MARS

 One Mars day is slightly longer than 24 hours and Mars revolves around Sun every 2 years. Much is known about Mars.
Topography is divided into two regions: Southern and Northern Hemispheres.
Southern Hemisphere has topographic highs and lots of craters.
Northern Hemisphere is topographically lower and less cratered.
Evidence of volcanism on surface suggests that volcanoes could still be active.
The composition of Mars is believed to be similar to that of Earth’s.
It is believed that water once existed on the Martian surface because features seen on the Martian surface appear to be formed by running water. No evidence that liquid water exists today.

 The atmosphere of Mars contains carbon dioxide and the planet is cold. Some questions as to whether life once existed on Mars.

 ASTEROID BELT

 An area between Mars and Jupiter that contains approximately 2000 rocky objects in orbit.
These objects are similar in composition to stony meteors, the largest is 1000 km in diameter.

 JUPITER

 The largest planet of the solar system yet it is less dense than the Earth.
Rotates EXTREMELY fast [1 Jupiter day = 10 hrs], revolves around Sun in 12 years.
Jupiter is believed to have a core composed of silicate and metal material in a liquid form surrounded by a hydrogen and helium gas shell thousands of km thick. This shell is under extreme pressures which cause Jupiter to be VERY hot.
Above this shell is an atmosphere containing layers of gas that include water vapor, helium gas, hydrogen sulfide and ammonia.
Jupiter is characterized by elongate bands of clouds encircling planet: this due to rapid spin. Great Red Spot: semi-permanent anticyclone (storm).
Jupiter has one small ring surrounding it and 14 moons.
Four of Jupiter’s moons are sizable: Io, Ganymede, Europa and Callisto. Each are unique.

 SATURN

 Almost as large as Jupiter with a very fast spin [one Saturn day = 10.7 hrs]. It takes 29.5 yrs to revolve around the Sun.
Saturn is also composed of a gas shell surrounding a liquid core but since shell is not under as intense pressure as Jupiter, Saturn is cold (average temp = -1800 C).
The most prominent feature of Saturn is its rings.
Rings are composed of ice and rock particles that range in size from pebbles to boulders.
Saturn has 17 moons of varying size.

 URANUS and NEPTUNE

 Uranus and Neptune are very similar to one another. They are classified as gas giants because they have an atmosphere of hydrogen, helium and methane. They are larger than the Inner planets but much smaller than Jupiter or Saturn. Both Uranus and Neptune are believed to be composed of a solid core of silica and iron surrounded by a liquid layer of methane and ammonia. Both have an atmosphere of hydrogen and helium.

 URANUS

 One Uranus day = 15.6 hrs and it takes 84 yrs to revolve around the Sun.
Uranus has 15 moons and a ring system.

 NEPTUNE

 One Neptune day = 17.9 hrs and it takes 165 yrs to revolve around the Sun.
Neptune has 8 moons and a ring system.
Neptune has a feature called the Great Dark Spot that is believed to be similar to the Great Red Spot of Jupiter.

 PLUTO

 Pluto is very small and very distant from the Sun. Its rotation is very slow [1 Pluto day = 6.4 Earth days] and it takes 248 yrs to revolve around the Sun.
It is believed to be composed of frozen methane.