Transcript Integrated Science

The Solar System and Universe
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Most astronomers believe the universe began 10
to 15 billion years ago with a explosion called the
BIG BANG.
The space formed by the Big Bang was filled by
extremely energetic high frequency radiation
called the primeval fireball.
This radiation still survives today as microwaves,
which continually stretches out as the universe
expands.
When you gaze at the stars and far away galaxies you are
actually looking back in time, because of the time it takes
the light to travel such vast distances.
 Evidence of the expanding universe include the Doppler
Red shifts.
 Light waves are stretched when an object moves away
from us. (Red Shifts)
 Light waves are compressed when an object moves
towards us. (Blue Shifts)
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A. Penzias and R. Wilson were
two Bell Laboratories
engineers working on a
microwave communication
antenna in 1965. They
discovered that no matter
what they did they could not
get rid of a certain level of
background static that seemed
to be coming from every
direction. At first they thought
it was pigeon dropping on the
antenna.
Blue Shifts
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The Nebular Theory has these key features:
Begin with a giant cloud (nebula) of gas and dust (enriched with trace amounts of
heavy elements, i.e. those heavier than hydrogen and helium). Cloud may span
many light-years.
Regions of cloud compress due to acoustic waves, shock waves, or some other
kind of density waves.
Compressed regions begin to collapse under their own gravity.
Region become centrally condensed: more matter in center
As a region shrinks it becomes hotter due to conservation of energy: gravitational
potential energy is converted to kinetic energy.
As a region shrinks it begins to spin faster due to conservation of angular
momentum: like the ice-skater pulling in her arms.
The material begins to flatten into a disk as a natural consequence of collisions.
Protoplanetary disks such as those predicted by the theory have been
observed in regions of active star formation.
Protoplanetary disks such
as those predicted by
the theory have been
observed in regions of
active star formation.
Protoplanetary disks
such as those
predicted by the
theory have been
observed in regions
of active star
formation.
Protoplanetary disks such as those predicted by the theory have been observed
in regions of active star formation.
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The Nebular Theory has these key features:
At the center of the disk a Protostar is forming.
While in the disk colliding dust grains begin sticking together and condensing into
larger and larger bodies: Planetesimals.
Planetesimals collide, stick together, and begin self-gravitating.
Near the protostar temperatures are hot and light elements in gaseous form do
not condense out of the disk: small, rocky planets
Farther from the protostar planetesimals can collect vast quantities of gases
around them and grow larger and large in mass: A fracturing of the disk into
smaller disks occurs: larger gaseous planets with many moons.
Star blows a strong wind which eventually clears away all small debris and gas
that has not condensed out.
Terrestrial planets gain atmospheres through volcanic outgasing and comet
impacts.
Asteroids, Comets, and Meteoroids are left-over debris from the original Nebula
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Other Planetary Systems
If our ideas about how our own Solar System formed are correct then it is
reasonable to conclude that many, many other stars would have formed in the
same manner and would have planetary systems of their own. Planets around
other stars are hard to find. We cannot see their reflected light (too dim and
drowned out by star's light).
Until recent years this had only been a hypothesis with no data. But now we have
very strong evidence that most stars, in fact, have planets around them.
Several teams of astronomers across the world have been using a similar
technique to find them. One team lead by UC Berkeley's Geoff Marcy has been
very successful. They have found these new worlds by their gravitational
influence on their parent star.
They look for a periodic "wobble" in the motion of the star due to the
gravitational tug and motion of the planet around it. The "wobble" is measured as
a Doppler Shift in the light from the Star.
Johannes Kepler, working with data painstakingly collected by
Tycho Brahe without the aid of a telescope, developed three
laws which described the motion of the planets across the sky.
1. The Law of Orbits: All planets move in elliptical orbits, with
the sun at one focus.
2. The Law of Areas: When the planet is closer to the sun, it
moves faster, sweeping through a longer path in a given
time.
3. The Law of Periods:. (The farther from the sun the greater
the time it takes to orbit the sun).
 Kepler's laws were derived for orbits around the sun, but they
apply to satellite orbits as well.
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The planets are known as wanderers because they change their positions with respect to the stars
but all with different periods.
The planets all wander through the Zodiac. They do this because all of the planets in our solar
system orbit the Sun in a plane. Their individual planes are all a tiny bit different from ours. So as
seen from Earth they will all be very close to the ecliptic plane (Earth's orbit). If they were all in
exactly the same plane they would all lie exactly on the ecliptic.
The planets' motions are sufficient slow that you need to watch over the course of several
days/weeks/months to notice them. So they still always rise in the East and set in the West.
Their general motion through the Stars is from West to East. This is because they are all orbiting
the Sun in the same direction as Earth is.
Occasionally they move East to West through the stars for a few months. This is called retrograde
motion. The planets do not actually change their directions in their orbits. Rather it's an optical
illusion caused when Earth passes the planet by.
The phases of Venus proved that the Earth rotated around the sun (heliocentric,
solar system, not a geocentric (earth centered))!
Galileo made these observations after making telescope.
Galileo published his observations and interpretations touting the heliocentric model
widely. He made no attempt to hide these discoveries, and it got him into a lot of
trouble. In 1633 Galileo was compelled to stand trial for "vehement suspicion of
heresy" by the Catholic Church. The Church had liked the idea of a Universe centered
on Earth. It had taught the Ptolemaic model as the correct one reinforced by biblical
scripture. Galileo was threatened with excommunication and death if he did not
recant his claims. Eventually he capitulated. There is a story (likely apocryphal) that
when Galileo recanted his belief that the Earth went around the Sun to the Church
court he muttered under his breath so that only those nearest could hear him say,
"and yet, it moves."
 Galileo was placed under house arrest for the remainder of his life. It was hardly a
punishment. He continued to do physics experiments involving rolling balls on inclined
surfaces, studying the motions of a pendulum, and dropping balls of different masses
to see which would fall fastest. The results of his experiments and his interpretations
would later lead Newton to reinvent physics and once again change the Universe
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