Chapter 4: A Star Called The Sun Flashcards
Throughout early human history, the sun was accepted as a God. Name 4 of the “sun gods” from different civilizations and the characteristics it was usualy given
Greek - Helios
Egyptian- Ra
Aztec - Tonatiuh
Inuit - Malina
Usually given human capabilities and perfect personality
Describe where the sun is located on a Hertzsprung-Russel Diagram
The Sun is a Mainsequence star.
On the smaller side of main sequence stars but brighter than 85% of stars in our Galaxy.
Describe the Anatomy of our Sun
- there is no solid surface - the sun is a ball of gas that gets denser toward the center
Photosphere
* appears as a solid layer but is not
* the density at which we can not see any deeper toward the core
* bright
* usually size of photosphere is taken for measurements of size of sun
**Chromosphere: **
* irregular layer of gases extends up from photosphere
* 2500km thick
* need special instruments to see because transparent to most visible radiation
Corona:
* outermost layer
* extends millions of km into space
* usually not visible becuase of the brightness of photosphere - visisble during a total solar eclipse.
Diameter of the sun?
~1.4 million km (about 109 x the diameter of Earth)
Volume of the sun
~1.3 milliion x the volume of earth
Mass of Sun
What % of the mass of our solar system is contained in the sun?
Mass is about 330,000 x Earth
Sun contains 99.8% of all the mass in the Solar system
Age of Sun
~4.6 billion years (earth is estimated at 4.6 and sun is slightly older than earth)
Why is the rotation period of the sun vary at diffrent altitudes? What is the rotation period at the equator? At the poles?
Why does the sun have an oblate shape? draw a diagram of this shape
The “rotation period” of the Sun refers to the time it takes for different parts of the Sun to complete one full rotation.
Because the Sun is not a solid object , as it rotates, mass is transferred to its middle, giving the whole body an oblate shape.
- At the Sun’s equator, it takes about 25 Earth days for the Sun to complete one full rotation.
- At the Sun’s poles, it takes about 35 Earth days for a full rotation.
What is the temperature of the sun (in Kelvin) at the surface vs the interior?
Surface temperature: 5800K
Interior: 15 million K
What is Kelvin? What is the zero point for K? How to calculate Kelvin from Celcius?
Kelvin is a scale of temperature, like celcius.
- They increase at the same rate but have a different starting point (zero point)
- Each dividion of celcius is equal to each division of K because they increase at the same rate (one degree change C is same as one degree change K)
- Example: A change from 20°C to 30°C is the same as a change from 293K to 303K.
0 degrees C: The point at which water freezes
0 degreees K: The point at which all motion within an atom ceases (equal to -273 degrees celcius)
Therefore, to calculate K, just add 273 degrees to celcius
What is an Astronomical Unit?
Why are these used for measuring distances within our solar system
**1 AU **= 150 million kilometers (distance between sun and earth)
- astronomical units are used when reffering to distances within solar system because light years are too big (ie. distance between sun and earth in LY is only 0.000016 light years, or 8 light minutes) and km are too small
- therefore, AU makes it easier to calculate and discuss measurements in solar system
How many AU is Mars from the Sun? Pluto?
Mars is 1.5 AU from the Sun
Pluto is 39.5 AU from the Sun
What does it mean to sample something directly vs. indirectly?
Direct sampling: physically taking a piece or portion of the object or substance and analyzing i
Indirect Sampling: using methods to analyze or understand something without physically taking a part of it. Instead, you gather information based on what the object emits, reflects, or how it interacts with its environment.
Describe Spectroscopy.
Is this a method of indirect or direct sampling?
What does spectroscopy aim to determine?
What is the device that is used? What does it do?
What are absorption lines and emission lines? What information do they give us?
Spectroscopy:
* a method that can be used to indirectly sample the sun
* Analyzing the light emitted (or absorbed) by a given material to determine it’s chemical composition
* because each element has a unique “finger print” of light
- The device used is a spectrometer or spectrograph which breaks up the light wavelengths into a spectrum of colours.
- When scientists look at this spectrum, they can see dark lines (called absorption lines) or bright lines (called emission lines) at specific points. These lines correspond to specific elements because each element absorbs or emits light at particular wavelengths.
What chemical composition of the sun has been found through spectroscopy?
1. Hydrogen - 71%
2. Helium - 27%
3. Oxygen - 0.97%
4. Carbon - 0.4%
5. Nitrogen - 0.096%
6. Silicon -0.099%
7. Magnesium - 0.076%
8. Neon - 0.058%
9. Iron - 0.014%
10. Sulfur - 0.04%
most of the 90ish natural known elements are found within the sun. Hydrogen and Helium are the most abundant, then oxygen makes up almost a full percent. the top 10 most abundant are listed.
What was the purpose of the Genesis Experiment
The Genesis Experiment was a mission by NASA designed to capture samples of particles directly from the solar wind (a stream of charged particles coming from the Sun) and bring them back to Earth for study – which would be our first direct sampling of the sun and would also closely resemble the orginal dust, gas and ice from which the various bodies in solar system evolved
From where and when was NASA’s Genesis Experiment Launched? Where was Genesis sent?
NASA’s Genesis, a robotic spacecraft, was launched in August 2001 from Cape Canaveral, Florida
It traveled to an area in space between Earth and Sun where the gravity of the two bodies is balanced (meaning it can stay in a stable position without getting pulled) and far away from interfering effets of any other planet.
There, it collected solar wind particles for more than 2 years.
How did Genesis capture solar wind?
Genesis team constructed collection tiles or foils of materials such as gold, saphhire, even diamonds.
In flight, an onboard computer decided which sample array would work best and continued with the collection task
Late in the mission, these collector arrays, and their samples, were retracted and stored in the spacecraft’s sample return capsule.
Which mission marked the first time NASA had collected any objects from farther than the Moon for retrieval to Earth?
Genesis mission to capture solar wind particles launched in 2001
For how many days did genesis collect solar wind samples?How large was the sample at the end?
over the 884 days, it captured charged atoms on it’s 5 disks, and the sample was **no bigger than a few grains of salt. **
still, scientists said this would be enough to reconstruct the chemical origin of the sun and its family of planets
What are prominences?
Prominences: These are arcs of gas that rise from the surface of the Sun into the outer atmosphere (called the corona). They look like glowing loops that can reach up to 10,000 kilometers above the Sun’s surface. They are anchored to the Sun’s surface and can last for days or weeks.
What are solar flares?
- short-lived gas eruptions
- generally last no more than 20 mins (a few have persisted for a few hours)
- Solar flares are sudden and intense bursts of energy that shoot out from the Sun’s surface.
- Flares are important because they can have direct effects on Earth. They can cause disruptions in communications systems and power grids, and they also contribute to the auroras (northern and southern lights) by interacting with Earth’s magnetic field.
Describe the Earth’s and the Sun’s magnetic field? Draw a diagram representing earth’s magnetic field.
can be crudely thought of as giant bar magnets - south at one end, north at other end
and there is a field of insivisble loops surrounding them - these are magnetic field lines that we express as lines showing the different direction and strength.
Describe what is going on in this graph
this is a graph of solar cycles from 1975 to 2005.
Solar irradience: the power per unit area received from the Sun in the form of electromagnetic radiation. This data shows how much energy from the Sun is hitting Earth’s atmosphere.
* depicted with the yellow lines
**Sunspot observations, solar flare index, and 10.7 Radio Flux **all follow the same trend.
They are all higher at solar maximum, and minimum at solar minimums
Describe what is being depicted in this image
This diagram represents Earth’s magnetosphere and its interaction with the solar wind
Solar Wind: This is the stream of charged particles, mostly electrons and protons, that flows outward from the Sun. These particles are shown coming from the left side of the image.
Bow Shock: This is the area where the solar wind slows down dramatically due to hitting the Earth’s magnetosphere. It’s similar to the wave that forms at the bow (front) of a boat as it moves through water.
Magnetopause: This is the boundary between the Earth’s magnetosphere and the solar wind. Inside this boundary, the Earth’s magnetic field is dominant.
Plasmasphere: This is a region inside the magnetosphere filled with low-energy charged particles. It is more or less aligned with the Earth’s magnetic field.
Magnetosheath: This area lies between the magnetopause and the bow shock. It is filled with solar wind particles that have slowed down and become turbulent due to the encounter with the Earth’s magnetic field.
Polar Cusp: These are funnel-like regions in the Earth’s magnetosphere where the Earth’s magnetic field lines curve down toward the polar regions. The cusps allow particles from the solar wind to enter Earth’s atmosphere, contributing to phenomena such as the aurora.
Magnetotail: This is the region of the magnetosphere that is stretched out directly away from the Sun by the solar wind, extending far beyond the night side of Earth. It consists of the North and South Lobes, which contain magnetic field lines pointing towards and away from Earth, respectively.
Plasma Sheet: Located between the lobes of the magnetotail, this is a region where the magnetic field lines come close together and reconnect, a process that can release large amounts of energy and is associated with magnetic storms on Earth.
Neutral Point: These are points in the magnetotail where the Earth’s magnetic field lines reconnect. This process can release bursts of energy contributing to geomagnetic storms and auroras.
Describe what is happening in this image
this shows the lifecycle of the sun
we are now at 4.6 billion years, about halfway through the mainsequence phase
at 10 billion years, all hydrogen fuel will be used up and will expand into red giant and start using helium as fuel
at 11 billion years, planetary nebula phase.
* A planetary nebula is a type of emission nebula consisting of an expanding, glowing shell of ionized gas ejected from red giant stars late in their lives.
at 12-24 years it will be a white dwarf
