Solar Astronomy Study Guide
The hotter region directly above the Sun's visible surface is called the what?
Chromosphere
What is the most common element in the Sun?
Hydrogen
What are sometimes used to contain fusion reactions during research?
Magnetic Bottles
Which part of the Sun has the greatest density?
The core
How do astronomers know the composition of the outer layers of the Sun?
We take an absorption line spectrum of the Sun. These absorption lines tell us what elements are present in the outer layers.
What is ignition temperature and how does it relate to fusion reaction?
When it's hot enough for fusion reactions to produce enough energy to be self-sustaining
On Earth, a period of low solar activity such as the Maunder Minimum, means what?
A climate with cooler temperatures
At the end of the p-p chain of nuclear fusion in the Sun, hydrogen nuclei have been converted into what?
A helium nucleus
Which of these groups of particles has the greatest mass?
A helium nucleus with two protons and two neutrons
What are plasmas?
A hot ionized gas consisting of approximately equal numbers of positively charged ions and negatively charged electrons; the "fourth state" of matter
What is nuclear fusion?
A process where the nuclei of atoms fuse
How does the number of neutrinos passing through your body at night compare with the number passing through your body during the day?
About the same
What is a solar flare?
An intense burst of radiation coming from the release of magnetic energy associated with sunspots. Flares are our solar system's largest explosive events. They are seen as bright areas on the sun and they can last from minutes to hours. We typically see a solar flare by the photons it releases. Flares are also sites where particles are accelerated
How will the Sun die?
As the Sun grows old, it will expand. As the core runs out of hydrogen and helium, the core will contract and the outer layers will expand, cool, and become less bright
Why does the Sun shine?
As the Sun was forming, gravitational contraction increased the Sun's temperature until the core became hot enough for nuclear fusion, which generates the heat that makes the Sun shine
Solar wind particles can be captured by the Earth's magnetosphere. When these particles spiral down along the magnetic field into the atmosphere, they are responsible for what?
Aurorae (Northern and Southern lights).
Iron is located at the bottom of the mass per nucleon graph, meaning it has the greatest what per nucleon?
Binding energy
What causes the cycle of solar activity?
Changes in the organization of the Sun's magnetic field
How was the Sun's chromosphere and corona discovered?
During total eclipses of the Sun
What is the condition needed for light nuclei to overcome electrical forces of repulsion during fusion?
Extremely high temperature
True or false? Helium is the most commonly used fuel for a fusion reactor
False
True or false? Nuclear fission and nuclear fusion are virtually the same process
False
Which of the following is NOT part of some active regions on the Sun?
Granulation
At the center of the Sun, fusion converts hydrogen into what?
Helium, energy, and neutrinos
The granulation pattern that astronomers have observed on the surface of the Sun tells us what?
Hot material must be rising from the Sun's hotter interior
How was the Sun formed?
It formed from a cloud of gas and dust that pulled together by mass gravitation. The extreme pressure caused by this great mass produced a nuclear fission reaction that fueled the Sun
As astronomers have learned more about the structure of the Sun, they found that it is what?
Made entirely of hot gas
Scientists estimate the central temperature of the Sun using what?
Mathematical models of the Sun
Astronomers have found that the level of the Sun's activity varies over centuries. How did they come to realize that this is so?
Measurements of the amount of radioactive carbon in tree rings, historical records of the number of sunspots seen on the Sun, and historical records of auroral activity
Today we realize that the source of energy for the Sun is a process called what?
Nuclear fusion
Where in the Sun does fusion of hydrogen occur?
Only in the core
Which of these things poses the greatest hazard to communication satellites?
Particles from the Sun
Solar energy leaves the core of the Sun in the form of what?
Photons
Most of the light we see coming from the sun originates in the what?
Photosphere
Which of these layers of the Sun is the coolest?
Photosphere
You are out on the beach, enjoying the warm sunshine with friends. As you glance up at the Sun, the part of the Sun that you can see directly is called its what?
Photosphere
What is the "Goldilocks Zone"?
Refers to the habitable zone around a star where the temperature is just right for liquid water to exist on an planet
Why did Mercury lose its atmosphere?
Since it's constantly bombarded by solar weather, its thin atmosphere is constantly being "blown away" into space
What is believed to occur when energy stored in a twist in the solar magnetic field above a sunspot is suddenly released?
Solar flare
The Sun's chromosphere contains many jet like projections that stick up into the transition region. These spikes of gas are called what?
Spicules
X-ray images of the Sun generally show what?
The Corona
How did Earth avoid the harsh fate of Venus?
The Earth is a perfect distance away from the Sun that none of the solar flares hit it
What causes sunspots?
The Sun's magnetic field welling up to the photosphere
What happens as you go upward from the Sun's photosphere?
The density (number of atoms in a unit volume) decreases
The lower and deeper you go into the Sun...
The higher the density and temperature
Astronomers have concluded that the Sun's activity varies in an 11-year cycle. Which of the following statements about this cycle is TRUE?
The number of sunspots gets larger and smaller over the course of 11 years
In the formula E = mc2, the letter c stands for what?
The speed of light
Why are solar storms, also known as CME, dangerous to Earth?
The violent ejections of solar gas, plasma, and electromagnetic radiation can extend billions of miles into space, possibly hitting the Earth
Why are Sunspots darker than the regions of the Sun around them?
They are cooler than the material around them
What causes solar flares?
They occur when a buildup of magnetic energy on the sun is suddenly released. They usually erupt from sunspots
What are spicules?
Thin, stringy features that look like tufts of grass
True or false? Thermonuclear fusion occurs in the Sun
True
