Lecture of October 3rd. Jennifer Blazejack

Introduction
The Solar System/Planets
The Formation of Our Solar System
Theories
The Birth of the Solar System
The Formation of the Planets
The Giant Impact
Conclusion
Introduction
We reviewed the Chapter 4 quiz. Gravity pulls objects in while friction slows down objects. A coin has greater potential energy when dropped from a high building and that energy turns into kinetic energy. Gravity does not push an ice skater's arms in. When she pulls her arms in her speed increases: the smaller the distance, the bigger the velocity. We discussed a little bit of how a student learns and that this is a class of concepts, not numbers. The deadline for joining was pushed off to a later date.
The Solar System/Planets
We studied Figure 6.1: The Solar System to understand the distances and orbits of planets. As for the planets, we reviewed what each planet was like and certain missions that took place in order to study the planets. It's hard to study the outer planets because they are made of gas. There was a huge debate about Pluto being a planet or not; and, Pluto was named a dwarf planet in the end. It was noted that collisions are very important in determining a planet's axis.  
The Formation of Our Solar System
There are four major features that determine what a solar system is:
1) Patterns of motion among large bodies: The Sun, planets, and large moons have organized orbits and rotate a certain way.
2) Two major types of planets: Small, rocky planets are closer to the Sun and large, gas-rich planets that are farther away from the Sun.
3) Asteroids and Comets: There are many and some are large enough to be dwarf planets. Asteroids and comets follow distinct patterns.
4) Exceptions to the rules: Uranus is tipped on its side and Earth is the only one with a large moon in the inner planets.
The small, rocky planets are called terrestrial planets (Earth like) and they are Mercury, Venus, Earth, and Mars. Terrestrial planets have few moons and no rings. The large, gas-rich planets are called jovian planets (Jupiter like) and they are Jupiter, Saturn, Uranus, and Neptune. Jovian planets have many moons and rings. Asteroids are "rocky bodies that orbit the Sun" like planets do and most can be found in the asteroid belt between Mars and Jupiter. Comets are "dirty ice balls" that orbit the Sun. Comets can be found in the Kuiper belt or Oort cloud.

Theories
The formation of the solar system is believed to be more complex due to recent discoveries. The nebular hypothesis is that the solar system formed from a giant cloud of interstellar gas. The nebular theory (originated from the nebular hypothesis) states that our solar system was born from a cloud of gas (solar nebula) that collapsed under its own gravity. Government funding and grants help provide money for this research, but it is very difficult to get. 
The Birth of Our Solar System
Hydrogen and helium are very important in forming our solar system. Earth is running out of helium. An important part of the creation is the solar nebula. As it collapsed its temperature increased. Then it went from a slow rotation to a fast one where it began to shrink. Afterwords, the solar nebula flattened into a disk. We watched an example of how angular momentum worked with the solar nebula. 
The Formation of Planets
Condensing gases is important. Even iron can become gas when it is hit hard enough. There were four types of materials in the solar nebula: hydrogen and helium, hydrogen compounds, rock, and metal. Because hydrogen and  helium gas made up most of the solar nebula it did not condense. Around the solar nebula other objects could condense. To explain this, it is important to remember the frost line- anything within the frost line is hot and anything outside the frost line is cold.  Inside the frost line (where it is warm) the terrestrial planets formed because metals and rock could condense. Outside the frost line (where it is cold) the jovian planets formed because hydrogen compounds could condense into ice. Accretion is the how "seeds" grow into planets. The example given was a vacuum cleaner. The bigger objects "cleaned up" the orbit by collecting smaller objects and formed planets. 
The Giant Impact
Many collisions took place and bombarded the planets. Collisions also determined the axis tilt of the planets.
Conclusion
We did not have enough time to do the last section. We were encouraged to watch the debates. We were also told about the mid-term taking place on the 17th and that we were be given a study guide.