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TuesdayOctober 9, 2012(Our Solar System –
Evolution of the Planets; Mercury & Venus; Video
Segment – Journey to the Edge of the Universe)
The Launch PadTuesday, 10/9/12
Why are the Gas Giant
(Jovian) planets more massive
than the terrestrial
planets, but less dense?
The Launch PadTuesday, 10/9/12
The Gas Giants are more massive because their strong gravitational fields drew in the light hydrogen
and helium gases that were abundant in the outer solar
system.
Gas Giants are less dense because they occupy a much greater volume than the terrestrial
planets do.
Remember, Density = mass/volume
Announcements
Assignment Currently Open
Summative or
Formative?Date Issued Date Due Date Into
GradeSpeed Final Day
Quiz 6 S1 10/5 10/5 10/19
WS – Planetary Info Chart
F1 10/5 10/9 10/11
Recent Events in ScienceHelix Nebula - Unraveling at the Seams
http://www.nasa.gov/multimedia/imagegallery/image_feature_2368.html
Read All About It!
A dying star is throwing a cosmic tantrum in this image from NASA's Spitzer Space Telescope. In death,
the star's dusty outer layers are unraveling into space, glowing
from the intense ultraviolet radiation being pumped out by the hot stellar core. This object, called
the Helix nebula, lies 650 light-years away, in the constellation of
Aquarius
Our Solar SystemThe planets in our solar system orbit close to a flat plane put into place by our protoplanetary
accretion disk 4.5 bya.However, the orbital planes of the planets are
slightly inclined.
Our Solar SystemThe planes of seven of the planets lie within 3
degrees of the Sun’s equator, but Mercury’s plane is inclined 7 degrees.
Dwarf planet Pluto’s plane is inclined 17 degrees.
Our Solar SystemTwo groups of planets occur in the solar system • Terrestrial (Earth-like) planets
• Mercury through Mars• Small, dense, rocky• Low escape velocities
• Jovian (Jupiter-like) planets • Jupiter through Neptune• Large, low density, gaseous• Massive• Thick atmospheres composed of hydrogen,
helium, methane, and ammonia• High escape velocities
Our Solar SystemPlanets are composed of: •Gases
hydrogen and helium•Rocks
silicate minerals and metallic iron•Ices
ammonia (NH3), methane (CH4),
carbon dioxide (CO2), water (H2O)
Evolution of the Planets The Nebular Hypothesis
The planets formed about 5 billion years ago.Our solar system condensed from a gaseous
nebula.As the planets formed, the materials that compose
them separated.• The dense, metallic elements (iron and nickel) sank
toward their centers.• The lighter elements (silicate minerals, oxygen,
hydrogen) migrated toward their surfaces.• This process is called chemical differentiation.
The Planets - A Brief Tour
Mercury• The innermost planet – 36
million miles from the Sun• The smallest planet – 3 015
miles in diameter• Has no atmosphere• Cratered highlands• Vast, smooth terrains• Very dense – average 5.4
g/cm3 (only Earth is denser)• Revolves quickly – only 88
days to circle the Sun• Rotates slowly – 59 days to
turn once on its axis
Mercury
Venus• Venus is the third most brilliant
object in our sky after the Sun and Moon
• Its similar to Earth in:• Size - 7 526 miles in diameter • Density – 5.2 g/cm3
• Earth’s closest neighbor after the Moon
• Shrouded in thick clouds that are Impenetrable by visible light
• Venus’ atmosphere is 97% carbon dioxide
• The surface atmospheric pressure is 90 times that of Earth
Venus• Venus’ Surface
• Mapped by radar, not visual observation
• Surface Features• 80% of surface is subdued
plains that are mantled by volcanic flows
• Low density of impact craters• Tectonic deformation must
have been active during the recent geologic past
• Thousands of volcanic structures
Venus
Venus Radar Map of Surface
Venus
Video Segment