Download The basic premise of the Nebular Model or Theory is that planets var

THE NEBULAR THEORY
TEXT (and CDROM “ Exploring the Planets: Introduction”)
The basic premise of the Nebular Model or Theory is that planets vary in their
composition as a consequence of their distance from the sun, and, their development
was a result of this composition and their size.
Use the information on page 166, 476-477 and 486 of the textbook or the chapter notes
package to explain why the planets are classified as terrestrial (inner) and Jovian (outer).
Nebular Theory
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A nebula is a cloud of gas and dust.
Approx. 5 bya, after a long period of gravitational attraction, a nebula finally coalesced.
This may have been started by a shock wave from an exploding star.
Like water going down a drain, it started to spin as it contracted into a disc shape.
Eventually, the density and temperature at its center began nuclear fusion, and started
the sun shining.
The rest of the gas and dust, that did not become part of the sun, became planets,
asteroids and moons.
The Inner Planets (AKA: The Terrestrial Planets)
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Mercury
Venus
Earth
Mars
The closer ones did not keep much of the lighter elements because they were
stripped away by the sun's heat.
They are mostly rocky with iron cores.
Thus, the inner planets are called terrestrial after “terra firma” meaning “solid ground.”
The Outer Planets: Jupiter (AKA: The Jovian Planets)
Jupiter
Saturn
Uranus
Neptune
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The "Gas Giants" or “Jupiter-like” planets are made mostly of hydrogen and helium,
and other light-weight elements and compounds.
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Pluto is small and rocky, possibly ice and rock, possibly an escaped moon of
Neptune's, possibly the largest comet and a member of the Kuiper Belt. It doesn't fit
the profile of a Jovian planet and was demoted in August 2006.
New “Dwarf” Planets
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Pluto & Eris – now considered Trans Neptune / Kuiper belt objects
Ceres – found in Asteroid Belt, larger than Pluto
Sedna – found in Oort Cloud (under consideration)