A Survey of the Solar System

Geocentric vs. Heliocentric

Planetary Orbits

Plu

toN

eptu

neUra

nus

Saturn

Jupi

terM

ars

Earth

VenusMercury

All planets in almost circular (elliptical) orbits around the

sun, in approx. the same plane

(ecliptic).

Sense of revolution: counter-clockwise

Sense of rotation: counter-clockwise (with exception of Venus, Uranus,

and Pluto)

Orbits generally inclined by no more than 3.4o

Exceptions:

Mercury (7o)

Pluto (17.2o)

(Distances and times reproduced to scale)

http://www.windows.ucar.edu/tour/link=/physical_science/physics/mechanics/orbit/perihelion_aphelion.html

Tipped over by more than 900

Mercury and Pluto: Unusually highly inclined orbits

Planetary Orbits and Rotation

Two Kinds of PlanetsPlanets of our solar system can be divided

into two very different kinds:

Terrestrial (earthlike) planets: Mercury, Venus, Earth, Mars

Jovian (Jupiter-like) planets: Jupiter, Saturn, Uranus, Neptune

Size of Terrestrial Planets Compared to Jovian Planets

Terrestrial PlanetsFour inner

planets of the solar system

Relatively small in size and mass (Earth is the

largest and most massive)

Rocky surface

Surface of Venus can not be seen directly from Earth because

of its dense cloud cover.

• Earth began forming ~ 4.6 bya

• For a few hundred million years Earth was very hot and constantly bombarded from space

• At this point there was no liquid water, life was impossible

• About 3,900,000,000 yrs ago, Earth was solidified enough and cool enough for liquid water

Early Earth

Conditions on Early Earth

• Oldest rocks: 3.9 billion years old

• 1st atmosphere – N2, H2, CO and CO2 – no O2 or ozone, high UV radiation and winds (present oxygen is created by life)

• Faint Early Sun: perhaps 30 per cent less bright

• Transition to atmosphere containing oxygen between 3.5 – 1.5 billion years ago

The Jovian PlanetsMuch larger in mass

and size than terrestrial planets

Much lower average density

All have rings (not only Saturn!)

Mostly gas; no solid surface

Other objects in the solar systemH.W. pg 720 ques. 1-15

• Comets- are dust and rock particles mixed with frozen water, methane, and ammonia.

• Halley’s Comet was discovered by Edmund Halley and it is seen every 75-76 years.

• Hale-Bopp comet- is the brightest comets man has seen. It was able to be seen in space for 18 months.

• A meteoroid- pieces of broken comets, when it burns up and enters Earth’s atmosphere it is than called a meteor, if it hits earth than it’s a meteorite.

• Asteroids are pieces of rock similar to the ones that formed planets. They lie between orbits of planets.

The Asteroid Belt

Plu

toN

eptu

neUra

nus

Saturn

Jupi

terM

ars

(Distances and times reproduced to scale)

Most asteroids orbit the sun in a

wide zone between the

orbits of Mars and Jupiter.

The Sun

• The sun is the closet star to Earth and gives us energy and the ability to have life.

• Photosphere- referred to as the surface of the sun and is where light is given off by the sun. Temp= 6,000 K

• Above that is the Chromosphere and above that is the largest layer of the suns atmosphere called the corona.

• The corona can have temps of 2 million K.

The Sun

• A sunspot is a place on the sun that is cooler than surrounding areas. They are not permanent, the appear and disappear frequently.

• Solar prominences are huge, arching columns of gas that protrude from the surface of the sun.

• H.W. pg 752 ques. 1-19