Ch. 10 Jennifer Blazejack

Introduction
10.1: A Closer Look at the Sun
10.2:Nuclear Fusion in the Sun
10.3: The Sun-Earth Connection
Conclusion + Side Notes
Introduction
We told about the 5 page term paper we are to write and to choose our topics. We were told about the new book of the week. There was the class slide show discussing the article that was currently being researched on.
10.1: A Closer Look at the Sun
The Sun is not on fire so it is not burning and the Sun is not contracting. What is happening is called nuclear fusion. Nuclear fusion needs high temperatures and density in order to occur. Basically, the Sun converts its mass into energy through nuclear fusion. Contraction stopped when nuclear fusion replaced energy radiation that went into space. The equation to follow for nuclear fusion is the following:

                                Nuclear Potential Energy (Core)  ~ 10 billion years

Luminosity

To understand the importance of nuclear fusion a breakdown of the Sun's structure is needed:
Solar wind: it is not physically part of the Sun, but it does come off the Sun. It is stream of charged particles.
Corona: it is the outermost layer of the Sun. It is possible to see the corona if you placed a coin over the Sun (the glowing layer that appears around the coin).
Chromosphere: it is the middle layer. It radiates the ultraviolet rays.
Photosphere: it is the lowest layer. It's the visible surface of the Sun.
Convection Zone: energy generated in solar core travels up. Cause the churning on the Sun's surface.
Radiation Zone: energy that moves outwards in the form of photons. It is bathed in X-rays.
Core: Sun's energy. Nuclear fusion transforms hydrogen into helium.
As the layers of the sun goes deeper than the pressure inside increases. This idea helps keep the balance of heating and cooling in the Sun, which will be explained later on. The weight of the Sun is counterbalanced by its energy and both must remain equal (energy both in and out). 
10.2: Nuclear Fusion in the Sun
*The important thing to remember is that fission is a large nucleus that splits into smaller nuclei and fusion combines smaller nuclei to form a larger one.*
In nuclear fusion a strong force binds protons and neutrons together. At low speeds, particles pass each other, but at high speeds particles can collide with the help of the strong force. As discussed before, nuclear fusion transforms hydrogen into helium in the Sun, but it does not just convert. Neutrinos and positrions (a positively charged electron) are created when two protons fuse and make a deuterium nucleus (this process occurs twice). Then the deuterium nucleus and a proton fuse to make helium (this process occurs twice). Then the two helium-3 nuclei fuse to form helium-4 that releases two excess protons.
The Solar Thermostat helps keep the Sun's temperature in check when it heats up over the average or the temperature drops below the average. It is best explained like this from figure 10.7 in the book, the Essential Cosmic Perspective, 6th edition:
"A slight drop in core temperature leads to a large decrease in the fusion rate that lowers the core pressure causing the core to contract and heat up ....thereby restoring the fusion rate to normal. A slight rise in core temperature leads to a large increase in fusion rate that raises the core pressure causing the core to expand and cool down....thereby restoring the fusion rate to normal".
10.3: The Sun-Earth Connection
The Sunspot cycle occurs every 10 to 11 years. Sun spots are cooler than the Sun's surface because of strong magnetic fields.  When heat is organized it is a bright color and when there is an absence of heat it is a dark color (such as sunspots on the surface). We are now able to measure sunspots because of the Zeeman effect, which measures the magnetic fields of sunspots by observing the splitting of spectral lines. Solar flares can be seen in Chicago.
Conclusion
We were reminded about the term paper and the PowerPoint based on our topic.