studying the solar system our goals for learning what does the solar system look like? what can we...
TRANSCRIPT
Studying the Solar System
• Our goals for learning
• What does the solar system look like?
• What can we learn by comparing the planets to one another?
• What are the major features of the Sun and planets?
• Eight major planets with nearly circular orbits
• Pluto (dwarf planet) is smaller than the major planets and has a more elliptical orbit
Swarms of Smaller Bodies
• Asteroids
• Kuiper Belt Objects
• Oort Cloud
• Comets (short period, long period)
History of Planet Count
8Re-classification of Pluto, Eris & Ceres as “Dwarf planets”, others to follow as debate continues
2006
9?Discovery of several large KBOs, especially Eris which is larger than Pluto.
2000-2005
9?Discovery of 1992 QB1 and other Kuiper Belt Objects1992-1999
9?Discovery of Charon1978
9Discovery of Pluto1930
8Re-classification of Ceres and other small bodies1851
13+Discovery of Neptune1846
12Discovery of Astrea1845
11Discovery of Ceres, Palls & Vesta1801-1807
7Discovery of Uranus1781
6Heliocentric System, (Copernicus)1550
7Geocentric universe: Sun, Moon & 5 planetsAntiquity
Planet CountClassificaction/EventYear
What Counts as a Planet?
The IAU definition of a planet (2006):
• is in orbit around the Sun,
• has sufficient mass so that it is nearly round
• has "cleared the neighborhood" around its orbit.
Comparative Planetology
• Comparing the planets reveals common patterns. Those patterns provide insights that help us understand Earth
• Stay focused on processes common to multiple worlds instead of individual facts specific to a particular world.
• We can learn more about a world like our Earth by studying in context with other worlds in the solar system.
Density and Composition
Density = = mass _ volume
• Measure a planet’s volume
• Measure a planet’s spin => calculate mass
• Result is a world’s bulk density.
g/cm3
Density and Composition
• Common materials• Metals (mostly Iron) 7.9 g/cm3
• Rock (mostly Basalt) 3.3 g/cm3
• Carbon & hydrogen ices 0.4-1.5 g/cm3
(volatiles)• H and He gases <<0.01 g/cm3
Density and Composition
• Earth 5.5 g/cm3 composition- iron, rock
• Saturn 0.7 g/cm3 composition- some rock, volatiles and lots H&He
• Callisto 1.9 g/cm3 Titan 2 g/cm3 composition -rock and ice
Thought Question
Planet Mars has a bulk density of 3.9 g/cmg/cm33 What materials is it made of ?
A) Metal and Rock
B) Rock and volatiles
C) Rock and H&He
D) Volatiles and H & He
What have we learned?
• What does the solar system look like?– Planets orbit Sun in the same direction and in
nearly the same plane.• What can we learn by comparing the planets to
one another?– Comparative planetology looks for patterns
among the planets. – Those patterns give us insight into the general
processes that govern planets– Studying other worlds in this way tells us
about our own Earth
What have we learned?
• How can we tell what planets are made of?– The bulk density of the planets reflect the type
of materials the planets are composed of.
– There are 4 main common types of material
– Most planets are made of a mixture of these materials that are not necessarily represented on the surface.
• Over 99.9% of solar system’s mass• Made mostly of H/He gas (plasma)
Sun
What are the major features of the Solar System?
Three Main Types of Large Bodies
• Terrestrial planets (rocky worlds)
• Jovian planets
• (gas giant worlds)
• Ice worlds (mostly moons and dwarf planets)
Terrestrials vs Jovians• The terrestrial (or rocky) worlds are the 4 inner
planets plus our Moon– They have a solid rock surface with an iron
core and a weak to no atmosphere or magnetic field.
• There are 4 jovian (or gas giant) planets– These planets have NO solid surfaces – just gas
and clouds that get denser as you move to their center.
– They are mostly atmosphere around rocky cores and have a strong magnetic field
Jupiter – largest gas giant world
Earth – largest rocky world
gas giant worlds are much larger than rocky worlds
Ice Worlds• Enough self-gravity to be spherical.
• Metal/rock core, ice mantle and crust.
• Some geological activity
• Two main locations:– Larger Icy moons orbiting gas giant planets– Largest objects in Kuiper belt in the outermost
solar system (Pluto, Sedna, Quoaor and others)
Swarms of Smaller Bodies
• Many rocky asteroids and icy comets populate the solar system
• Solar system debris can be found everywhere, but close to the sun it is rocky and far from the sun, icy.
What have we learned?
• What are the major features of the Solar System– Motions of large bodies: All in same
direction and plane– Two main planet types: Terrestrial and jovian– Minor type: ice worlds– Swarms of small bodies: Asteroids and
comets
© 2014 Pearson Education, Inc.
Which planets DO have rings?
A.Saturn onlyB.Saturn and Uranus onlyC.Saturn, Uranus and Neptune onlyD.Saturn, Jupiter, Uranus and Neptune onlyE.All the planets have rings.