© 2011 pearson education, inc. the solar system. © 2011 pearson education, inc. now known: solar...
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© 2011 Pearson Education, Inc.
The Solar System
© 2011 Pearson Education, Inc.
Now known: Solar system has 166 moons, one star, eight planets (added Uranus and Neptune), eight asteroids, and more than 100 Kuiper belt objects more than 300 km in diameter (smaller asteroids, comets, and meteoroids)
An Inventory of the Solar System
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An Inventory of the Solar System
More than 400 extrasolar planets have been found
Understanding planetary formation in our own solar system helps understand its formation as well as formation of other systems
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All orbits but Mercury’s are close to the same plane
The Overall Layout of the Solar System
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The Overall Layout of the Solar System
Because the planet’s orbits are close to being in a plane, it is possible for them to appear in a straight line as viewed from Earth. This photograph was taken in April 2002.
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Terrestrial and Jovian PlanetsIn this picture of the eight planets and the Sun, the differences between the four terrestrial and four jovian planets are clear.
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Terrestrial and Jovian Planets
Turn to your neighbor an list all the differences you see between the Terrestrial and Jovian planets.
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Terrestrial planets:
Mercury, Venus, Earth, Mars
Jovian planets:
Jupiter, Saturn, Uranus, Neptune
Terrestrial planets are small and rocky, close to the Sun, rotate slowly, have weak magnetic fields, few moons, and no rings
Jovian planets are large and gaseous, far from the Sun, rotate quickly, have strong magnetic fields, many moons, and rings
Terrestrial and Jovian Planets
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TerrestrialDifferences among the terrestrial planets:
• All have atmospheres, but they are very different; surface conditions vary as well
• Only Earth has oxygen in its atmosphere and liquid water on its surface
• Earth and Mars spin at about the same rate; Mercury is much slower, Venus is slow and retrograde
• Only Earth and Mars have moons
• Only Earth and Mercury have magnetic fields
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Asteroids and meteoroids have rocky composition; asteroids are bigger
Asteroid Eros is 34 km long
Interplanetary Matter
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Comets are icy, with some rocky parts
Comet Hale-Bopp
Interplanetary Matter
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Interplanetary Matter
Pluto, once classified as one of the major planets, is the closest large Kuiper belt object to the Sun
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Turn to your neighbor
Discuss your theory of how the solar system formed. Why do you think that? What characteristics of the solar system might your theory address?
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How Did the Solar System Form?Solar system properties show it has a
high degree of order
1. Each planet is relatively isolated in space2. The orbits of the planets are nearly circular3. All planets but Mercury lie in the same plane4. Rotational direction around the sun is the same
direction as the sun rotates5. Planets are differentiated between terrestrial and Jovian6. Asteroids are very old7. The Kuiper belt is asteroid-sized icy bodies8. The oort cloud comets are icy fragments that do not orbit
on the plane of the ecliptic
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Nebular contraction:
Cloud of gas and dust contracts due to gravity; conservation of angular momentum means it spins faster and faster as it contracts
How Did the Solar System Form?
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How Did the Solar System Form?Nebular contraction is followed by condensation around dust grains, known to exist in interstellar clouds such as the one shown here.
Accretion then leads to larger and larger clumps; finally gravitational attraction takes over and planets form.
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Aug. 24, 2006Demotion of Pluto
“Plutoed” -meaning to demote or devalue someone
Dr. Mike Brown and Neil Degrase Tyson to “blame”
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Eris is at fault
• Found large asteroids by 1851 (including Ceres) between Mars and Jupiter
• Pluto not in the asteroid belt but in the Kuiper belt
• Then we discovered Eris, which is in the Kuiper belt
• However Eris is classified Pluto would be classified (both have large inclinations)
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2006 IAU meetingPlanet Criteria
1. Must orbit the sun
2. Enough gravity to shape itself into a sphere
3. Big enough to clear its neighborhood around its orbit
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Dwarf planet criteria
1-2 are the same
3. Not cleared its neighborhood around its orbit
4. Not a moon
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Plutoid criteriaSame criteria as dwarf planet except
5.Must orbit beyond Neptune
Known Plutoids:
Pluto, Haumea, Makemake,Eris “Pluto Heard ME”