Chapter 11 Flashcards
Life on Earth depends on what from the Sun?
-Life on Earth depends on the light, heat, and energy from the Sun
True of False: The Sun is farthest star to Earth
False. It is the closest star to Eart
Why does the Sun Shine?
- Because it is a large ball of burning coal or wood
- Gravitational Contradiction
- materials contracts and energy converts into heat and radiation (light)
The core of the Sun is?
Hotter and denser than the surface
From what was the Sun born?
From the gravitational collapse of the Solar Nebula
What was the solar nebula composed of?
Hydrogen and Helium
What does Nuclear Fusion do?
Nuclear Fusion at the Sun’s core liberates energy and light that generates pressure that expands the Sun
What is inside the Sun’s Interior?
- Core
- Radiation Zone
- Convection Zone
- Photosphere
- Chromosphere
- Corona
- Solar Wind
What is the core?
15 million K, nuclear fusion occurs (energy production)
What is the Radiation Zone?
10 million K, energy is transported outward through radiation (light)
What is the Convention Zone?
Temperature decreasing outwards down to 5,800 K, energy is transported outward by movement of matter
What does the Core, Radiation and Convection zone have in common?
Temperature, density, and pressure decrease outwards
What is the Photosphere?
5,800 K emits mostly visible light. This is the innermost solar layer that we can see
What is the Chromosphere?
10,000 K emits most of the sun’s ultraviolet radiation
What is the corona?
1 million K emits most of the Sun’s X-Rays
What is the Solar Wind?
Ionized particles (plasma) moving at 450 km/s and extends throughout the solar system
What is Fission?
A large atom, such as uranium and plutonium, splits into 2 smaller atoms
What is Fusion?
2 small atoms combine into a single larger atom
What happens to nuclei at low speeds?
At low speeds, electromagnetic repulsion prevents the collision of nuclei. Two nuclei repel each other through electromagnetic forces (both have positive charge)
What happens to nuclei at high speeds?
At high speeds, nuclei come close enough for strong force to bind them together. The electromagnetic repulsion is overcome, and the nuclei come close enough together for the strong force to bind them.
How do we know what goes on under the surface of the Sun?
1) Astronomers create mathematical models that use the laws of physics, the Sun’s observed composition and mass, and computers to predict internal conditions.
2) By measuring Doppler Shifts, we observe vibrations of the Sun’s surface that are created deep within the Sun.
What are the 3 steps of Nuclear Fusion?
1) 4 Hydrogen nuclei -> 1 Helium nuclei
2) energy is released in form of radiation (gamma rays)
3) 2 neutrinos are produced
What is solar thermostat?
Results the balance between pressure and gravity
What do stable conditions of the sun maintain?
It maintains a steady energy production at the core
How does the energy from nuclear fusion get out of the Sun?
- Radiation Zone
- Convection Zone
- Photosphere
What happens in the Radiation Zone?
Energy goes through by “photon scattering”. Light bounces randomly off the matter, on average moving outwards.
What happens in the convection zone?
Energy goes through by movement of gases. Hot plasma moves upwards, cooler gas moves downwards.
What happens in the photosphere?
Show bright spots in a mottled surface. That is when we can see the upper surface of the convection zone.
How do we know what is happening inside the sun?
1) Mathematical models applying fundamental physical laws, and test them against known observed parameters of the Sun (mass, energy, emission, radius)
2) Current models are consistent with observed parameters, indicating that the models are very likely making an accurate description
What is needed to account for the Sun’s energy emission?
Electron neutrinos produced by the nuclear fusion
What is the “Solar Neutrino Problem”?
The first attempts to measure neutrinos from the Sun, measured only electron neutrinos thus amount of neutrinos detected was too few to account for the Sun’s energy emission
What is Solar Activity?
Changes in time of the Sun’s surface
What are sunspots?
- Appear less bright than their surroundings (“dark spots”)
- ~4,000K while surroundings ~5800K
- repel hotter gassed avoiding convection
- last a few weeks
Where are Magnetic fields detected?
Through the splits of spectral lines in the spectrum
What is the Sun composed of?
Ionized gas or plasma
What are magnetic fields?
Likely forces repelling hotter gases from sunspots
What is a solar prominences?
Ionized gases from chromosphere and the corona are trapped in magnetic fields forming solar loops
What is a solar storm?
Sudden changes in prominences
What are solar flares?
Eject High energy particles into space and generate x-rays. Believed to be generated by magnetic fields when they become too twisted
Different Sun Temperatures
- From the Core to the Photosphere the Sun’s temperature decreases.
- From the Photosphere to the Chromosphere to the Corona the Sun’s temperature increases.
- Solar atmosphere starts cooling down again in solar wind
Why do the Chromosphere and Corona heat up rather than cool down?
It is the result of transport of energy through magnetic fields. Hotter places of the Corona tend to be above sunspots
How does Solar Activity affect us?
- High energy particles can cause auroras (colors in the sky)
- Can affect communication satellites
- electric systems by generating geomagnetic storms
How does Solar Activity vary with time?
Solar Activity (Solar weather) is unpredictable as weather on Earth. Like on Earth, solar activity also has trends (Seasons).
What is the Sunspot Cycle?
Periodic variation in time of the number of sunspots. Average period of 11 years. Varies from 7-15 years.
What is Solar Minimum?
Time at which the number of sunspots is minimum
What is Solar maximum?
Time at which the number of sunspots is maximum
What is the Sunspot cycle latitudes?
- At beginning, sunspots appear mid-latitudes (30-40 degrees)
- At middle, sunspots appear between mid-latitudes and the equator
- At end of cycle, sunspots tend to appear near the equator
What is the cause of the Sunspot Cycle?
- convection is believed to transport magnetic fields from the sun’s interior to the photosphere.
- plasma bends magnetic field
- mf twist forming sunspots
- convection mixes gas of sunspots with surroundings and they disappear
What is the solar neutrino problem?
Early experiments designed to detect solar neutrinos found them, but in fewer numbers than had been expected
Why are sunspots cooler than the surrounding solar surface?
Because strong magnetic fields slow convection and prevent hot plasma from entering the region
