Transcript Document 7292823

Week 8 Day 3 Announcements
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Homework:
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Homework assignments for Chs 4 & 5 will post tomorrow
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The Solar System
Chapter 4
Ingredients?
The Sun
● Planets
● Moons and Rings
● Comets
● Asteroids (size > 100 m)
● Meteoroids (size < 100 m)
● Kuiper Belt
● Oort cloud
● Zodiacal dust
● A lot of nearly empty space
●
Solar System Formation Video
Artist’s view of early Solar System
initial gas and dust
nebula
dust grains grow by
accreting gas,
colliding and sticking
continued growth of
clumps of matter,
producing
planetesimals
planetesimals collide
and stick, enhanced
by their gravity
result is a few large
planets
Hubble Space Telescope
observation of disk
around young star with
ring structure. Unseen
planet sweeping out gap?
Clicker Question:
In the leading theory of solar system
formation, the planets:
A: were ejected from the Sun following a close encounter
with another star.
B: formed from the same flattened, swirling gas cloud that
formed the sun.
C: were formed before the Sun.
D: were captured by the Sun as it traveled through the
galaxy.
Discovery 4-1: What Killed the
Dinosaurs?
The dinosaurs
may have been
killed by the
impact of a large
meteor or small
asteroid.
The larger an
impact is, the less
often we expect it
to occur.
Dinosaur Killer Impact 65 million
years ago: an asteroid
with diameter roughly 10 km
High levels of iridium in Raton
Pass (I25)
The Fossil Record is Marked by Mass
Extinction Events
Extinction
Genus loss
End Ordovician
60%
End Devonian
57%
End Permian
82%
End Triassic
53%
End Cretaceous
47%
From Solé & Newman 2002
4.2 Interplanetary Matter
The impact of a large meteor can create a
significant crater.
The Barringer meteor crater in Arizona
4.2 Interplanetary Matter
The Manicouagan
reservoir in Quebec
Result from computer simulation of planet growth
Shows growth of terrestrial planets. If Jupiter's gravity not included, fifth
terrestrial planet forms in Asteroid Belt. If Jupiter's gravity included, orbits
of planetesimals there are disrupted. Almost all ejected from Solar System.
Simulations also suggest that a few Mars-size objects
formed in Asteroid Belt. Their gravity modified orbits of
other planetesimals, before they too were ejected by
Jupiter's gravity.
Asteroid Ida
Clicker Question:
We can tell something of the composition of
the planets by looking at their:
A: spectra
B: radius
C: mass
D: magnetic fields
Clicker Question:
An asteroid impact like the one that killed
off the dinosaurs is expected once every:
A: year
B: hundred years
C: thousand years
D: hundred thousand years
E: hundred million years
The Structure of the Solar System
L3
L5
L4
~ 5 AU
~ 45 AU
Lagrange Points
4.2 Interplanetary Matter
The inner solar
system, showing
the asteroid belt,
Earth-crossing
asteroids, and
Trojan asteroids
4.2 Interplanetary Matter
Large picture:
The path of
Icarus, an Earthcrossing asteroid
Inset: Ceres, the
largest asteroid
4.2 Interplanetary Matter
Asteroids and meteoroids have rocky composition;
asteroids are bigger.
(below)
Asteroid
Gaspra
(above) Asteroid
Ida with its
moon, Dactyl
(above)
Asteroid
Mathilde
4.2 Interplanetary Matter
Asteroid Eros
4.2 Interplanetary Matter
Comets are icy, with some rocky parts.
The basic components of a comet
4.2 Interplanetary Matter
The solar wind means the
ion tail always points away
from the Sun.
The dust tail also tends to
point away from the Sun,
but the dust particles are
more massive and lag
somewhat, forming a
curved tail.
4.2 Interplanetary Matter
The internal structure of the cometary nucleus
4.2 Interplanetary Matter
The size, shape, and orientation of cometary orbits
depend on their location. Oort cloud comets rarely
enter the inner solar system.
4.2 Interplanetary Matter
Meteor showers are
associated with comets –
they are the debris left
over when a comet
breaks up.
4.2 Interplanetary Matter