Transcript The Structure of Our Solar System

The Structure of Our Solar
System
Past ideas vs. Current Knowledge
Can it change over time?
Current Knowledge
• The solar system consists of the
sun, nine planets, their 158 moons
and a belt of asteroids and comets.
• There are over 130 satellites of
planets
• Venus, Earth, Mercury, Mars and
the sun are all parts of the inner
solar system.
• Outer solar system consists of
Neptune, Saturn, Uranus, Pluto and
Neptune.
• Between the orbits of Mars and
Jupiter lies the main asteroid belt.
Composition Jupiter, Uranus,
Categories
Mercury, Venus,
Earth, Mars have
rocky (terrestrial)
terrain. This
results in few
satellites and
rings, high density
and slow orbit.
Saturn and Neptune
are gas (Jovian)
planets. They are
mostly comprised of
helium and
hydrogen. They are
opposite of
everything the
previous planets.
They have many
satellites and rings,
low density, and
quick rotation.
Categories Continued
Size Small planets are those with a diameter than is
equal to or less than 13,000 km. These planets
are Mercury, Mars, Earth, Venus and Pluto.
 Giant planets are classified as those with a
diameter greater than 48,000 km. These planets
are Neptune Uranus, Jupiter and Saturn.
When and How the Solar System was
Uncovered
1610- 1684 17 bodies were revealed
1781- 1789 5 more bodies were found
1846- 1898 9 major bodies discovered
1904-1978 13 major bodies
1979- 1990 27 small moons found
Past Ideas
Heliocentric Theory
• Proposed by Aristarchus (270 B.C.) He thought that
the sun was in the center and all the planets except
for the moon orbited around it. He thought that the
moon orbited around the Earth. No one believed
him at the time because
A) They didn’t think the
Earth could be moving
and people wouldn’t
feel it.
B) People also
believed that if
Earth was moving
there would have
to be a shift in the
positioning of the
stars
C) In addition, many
believed that Earth had
to be the center of the
universe because all
those people were selfcenter
Geocentric Theory
Claudius Ptolemy proposed this theory.
He then wrote 13 volumes on the motion of
planets in 140 A.D. He wrote about
Epicycles- circles that the planets
orbit on
Using epicycles to make backward
orbits (retrograde) more visible
Ptolemy explained that retrograde
was due to western drift. Western
drift makes it seem as if its going
backwards.
Church backed this theory and
anyone who went against it was put
under house arrest
Copernican Theory
Copernicus reinvented the
Heliocentric theory and challenged
the church’s principles
In case you forgot….. This theory
stated that the sun was the center
Science revolution!!
Copernicus still used epicycles to
explain motion, but it was more
confusing than the Geocentric
theory.
Keplerian Theory
Used flattened circles or ovals
(ellipses) instead of circles for
planetary orbits
No longer needed the epicycles
So far the most accurate system of
finding the motion of planets
Explained motion by the
1)semi-major axis
2)the peculiarity
3) the inclination
4) the longitude of the ascending bump
5) the argument of the point closest to
the approaching planet (perihelion)
6) the time of the perihelion.
Galileo
• Pioneer of observation
• Developed laws of motion
• Found that the Earth is not the
center by the fact that
1)spots on the sun
2) mountains on the moon
3) milky way is made up of
lots of stars
4) Venus has phases
5) Jupiter has moons
Tycho Brahe
and his scientific contributions
Background Information
• Tycho had the bridge of his nose
cut off in a duel, so he was replaced
it with a metal plate.
• Lived on the island of Hven, which
is located between Denmark and
Sweden, given to him by the Danish
King
• Brahe had a magnificent castle
build there, and an underground
observatory called Uraniburg.
• Brahe’s castle was his sanctuary
and main center of his astronomy
work.
Contributions
• Tycho invented and
calibrated new machines for
astronomical observation
• Brahe and his team
observed the bodies and
orbits of planets
• He also corrected his
observations according to
atmospheric refraction-The
change in direction of a ray of light as it
passes from space into the atmosphere.
Contributions Cont.

1st modern database and calculated the
distance of planets and starts most
accurately for his time
 discovered that the sun is farther from
the Moon than the Earth
 supported geocentric theory
 found that planets are on
elliptical orbits
Contributions Continued
1572- Brahe detected a new star in Cassiopeia
 Cassiopeia is a constellation
1577- He observed a comet and drew the
conclusion that the comet is not closer to the
Earth than the moon. Aristotle was wrong!
Bibliography
“Planets and the Celestial Sphere.”
http://zebu.uoregon.edu/~js/ast221/lecture
s/lec06.html. 5/10/06
Namowitz, Samuel N. and Nancy E.
Spaulding. Earth Science. Canada: D.C
Heath and Company, 1994.
Greogry L. Vogt. Solar System. New York:
Scholastic Inc., 2002.
Interactive sites
http://www.solarsystem.org.uk/planet10/
http://www.bbc.co.uk/science/space/solarsystem/