Planetary Orbits Pluto Neptune Uranus Saturn Jupiter Mars Earth Venus Mercury 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 3.4 o Exceptions: Mercury (7 o ) Pluto (17.2 o ) (Distances and times reproduced to scale) 0
Planetary Orbits and Rotation Tipped over by more than 90 0 Mercury and Pluto: Unusually highly inclined orbits 0
Two Kinds of Planets Planets 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 0
Size of Terrestrial Planets Compared to Jovian Planets
Terrestrial Planets Four 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. 0
<ul><li>Earth began forming ~ 4.6 bya </li></ul><ul><li>For a few hundred million years Earth was very hot and constantly bombarded from space </li></ul><ul><li>At this point there was no liquid water, life was impossible </li></ul><ul><li>About 3,900,000,000 yrs ago, Earth was solidified enough and cool enough for liquid water </li></ul>Early Earth
Conditions on Early Earth <ul><li>Oldest rocks: 3.9 billion years old </li></ul><ul><li>1 st atmosphere – N2, H2, CO and CO2 – no O2 or ozone, high UV radiation and winds (present oxygen is created by life) </li></ul><ul><li>Faint Early Sun: perhaps 30 per cent less bright </li></ul><ul><li>Transition to atmosphere containing oxygen </li></ul><ul><li>between 3.5 – 1.5 billion years ago </li></ul>
The Jovian Planets Much larger in mass and size than terrestrial planets Much lower average density All have rings (not only Saturn!) Mostly gas; no solid surface 0
Other objects in the solar system H.W. pg 720 ques. 1-15 <ul><li>Comets- are dust and rock particles mixed with frozen water, methane, and ammonia. </li></ul><ul><li>Halley’s Comet was discovered by Edmund Halley and it is seen every 75-76 years. </li></ul><ul><li>Hale-Bopp comet- is the brightest comets man has seen. It was able to be seen in space for 18 months. </li></ul><ul><li>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. </li></ul><ul><li>Asteroids are pieces of rock similar to the ones that formed planets. They lie between orbits of planets. </li></ul>
The Asteroid Belt Pluto Neptune Uranus Saturn Jupiter Mars (Distances and times reproduced to scale) 0 Most asteroids orbit the sun in a wide zone between the orbits of Mars and Jupiter.
The Sun <ul><li>The sun is the closet star to Earth and gives us energy and the ability to have life. </li></ul><ul><li>Photosphere- referred to as the surface of the sun and is where light is given off by the sun. Temp= 6,000 K </li></ul><ul><li>Above that is the Chromosphere and above that is the largest layer of the suns atmosphere called the corona. </li></ul><ul><li>The corona can have temps of 2 million K. </li></ul>
The Sun <ul><li>A sunspot is a place on the sun that is cooler than surrounding areas. They are not permanent, the appear and disappear frequently. </li></ul><ul><li>Solar prominences are huge, arching columns of gas that protrude from the surface of the sun. </li></ul><ul><li>H.W. pg 752 ques. 1-19 </li></ul>
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