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ch.1 astronomy > ch.12 > Flashcards

ch.12 Flashcards

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1
Q

What is the Sun?

A

A star, a luminous ball of gas more than 100 times bigger than the Earth

The Sun is the central star of the Solar System.

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2
Q

What activity is revealed by telescopic observations of the Sun?

A

Violent activity, including fountains of incandescent gas and twisting magnetic fields

This activity is not visible to the naked eye.

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3
Q

What is the core of the Sun primarily responsible for?

A

Converting hydrogen into helium through thermonuclear fire

This process produces energy equivalent to the detonation of 100 nuclear bombs.

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4
Q

How does the force of gravity affect the Sun?

A

It keeps the Sun in check, preventing it from collapsing under its own mass

The Sun’s mass is 300,000 times that of Earth.

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5
Q

What is the Sun’s distance from Earth?

A

About 150 million km or 1 AU

This distance was historically measured by triangulation, now done by radar.

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6
Q

What is the diameter of the Sun?

A

About 1.4 million km

This is derived from its angular size of about 1/2 degree.

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7
Q

What is the surface gravity of the Sun relative to Earth?

A

30 times that of Earth

This is based on the Sun’s mass and radius.

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8
Q

What is the surface temperature of the Sun?

A

5780 K

This can be determined using Wien’s law for a blackbody.

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9
Q

What is the core temperature of the Sun?

A

15 million K

This temperature is necessary for nuclear fusion to occur.

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10
Q

What percentage of the Sun’s composition is hydrogen?

A

71%

Helium makes up 27% of the Sun’s composition.

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11
Q

What are the inner layers of the Sun, from inner to outer?

A
  1. Core
  2. Radiative zone
  3. Convection zone
  4. Photosphere
  5. Chromosphere
  6. Corona

These layers play different roles in the Sun’s structure and function.

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12
Q

What is the photosphere?

A

The low-density upper layer of the Sun where photons can escape into space

It appears yellow and is visible to the naked eye.

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13
Q

What occurs in the radiative zone?

A

Energy moves outward by photon radiation

This region surrounds the Sun’s core.

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14
Q

What characterizes the convection zone?

A

Energy is transported by the rising and sinking of gas

This is above the radiative zone.

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15
Q

What is the temperature pattern in the Sun’s atmosphere?

A

Decreases immediately above the photosphere but increases at higher altitudes

The corona can reach temperatures of several million Kelvin.

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16
Q

What are solar neutrinos?

A

Particles created by the nuclear fusion process in the Sun’s core

They escape the Sun’s interior and can be detected on Earth.

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17
Q

What causes sunspots?

A

Magnetic field activity

They appear as dark regions on the Sun’s surface.

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18
Q

What are solar flares?

A

Brief but bright eruptions of hot gas in the chromosphere

They are associated with sunspot activity.

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19
Q

What is the solar wind?

A

A stream of atoms from the corona that exceeds the escape velocity of the Sun

It consists primarily of hydrogen and helium.

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20
Q

What is the solar cycle?

A

The pattern of sunspot, flare, and prominence activity changing yearly

It peaks approximately every 11 years.

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21
Q

How does the Sun’s rotation affect its magnetic field?

A

It winds up the magnetic field, increasing solar activity

This leads to phenomena like sunspots and solar flares.

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22
Q

What is the core temperature of the Sun?

A

About 15 million K

This is crucial for nuclear fusion processes.

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23
Q

What is the temperature of the corona?

A

About 1 million K

The corona can be observed during a total solar eclipse.

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24
Q

What is the significance of the proton-proton chain?

A

It is the process through which protons are converted into helium in the Sun’s core

This process produces energy by nuclear fusion.

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25
What is the role of isotopes in the proton-proton cycle?
They are intermediate steps between protons and their fusion into helium ## Footnote This highlights the complexity of the fusion process.
26
How long does it take for energy created in the Sun’s center to reach its surface?
Approximately 16 million years ## Footnote This is due to the dense conditions within the Sun.
27
What is the effect of solar flares on Earth?
They can increase radio and x-ray emissions ## Footnote This can lead to auroras and other atmospheric phenomena.
28
What is the temperature at the Sun's core?
About 15 million K ## Footnote This is essential for sustaining nuclear fusion.
29
What is the core of the Sun primarily composed of?
Hydrogen ## Footnote Fusion processes convert hydrogen into helium.
30
What is the Sun's mass compared to the Earth?
300,000 times that of Earth ## Footnote The Sun's mass is a significant factor in its gravitational pull.
31
What occurs due to the sudden recombination of opposite polarity parts of the Sun's magnetic field?
A plasma confined to a magnetic tube sticking out of the surface of the Sun.
32
One way to probe the rate of nuclear reactions in the center of the Sun is by studying the _________ produced because _________.
Neutrinos, they pass out of the Sun without undergoing a random walk.
33
Why doesn't nuclear fusion in the Sun violate the law of conservation of energy?
Matter and energy are equivalent, as expressed by Einstein's equation E = mc2.
34
If the Sun's rotation carries two sunspots out of sight, you might see them again in about ________.
Two weeks
35
Activity on the surface of the Sun is primarily driven by ________.
Electromagnetism
36
Flares, mass ejections and activity in the solar corona are best studied using ________.
X-ray telescopes
37
From the center out, the correct order of the parts of the Sun is ________.
Core, radiative zone, convection zone, photosphere, chromosphere, corona
38
The Zeeman effect is used to measure _________ at the Sun's surface.
Magnetic field strength
39
The solar cycle is a result of ________.
Differential rotation of the Sun
40
In the Sun, nuclear fusion occurs ________.
Only in the core
41
True or False: Solar flares can increase the Sun's radio and X-ray emission by factors of a thousand in a few seconds.
True
42
True or False: The Sun rotates faster near its poles than near its equator.
False
43
True or False: The distance of the Sun from Earth is measured by bouncing radar waves off the Sun.
False
44
True or False: Astronomers use Wien's law to measure the temperature at the Sun's interior.
False
45
True or False: Astronomers use theory to determine the temperature of the Sun's core, because they cannot measure the core temperature directly.
True
46
True or False: The gases at the interior of the Sun are in a state of plasma, i.e., an ionized gas.
True
47
True or False: Below the photosphere, the temperature and pressure of the Sun increase steadily with increasing depth.
True
48
True or False: The Sun's surface is hotter than the solar corona.
False
49
True or False: Coronal holes are cooler parts of the corona from which the solar wind escapes.
True
50
True or False: The ideal gas law implies that raising the temperature and density of a gas increases the pressure of the gas.
True
51
True or False: Seismic waves observed at the surface of the Sun provide clues about the temperature and the density of the solar interior.
True
52
True or False: The energy produced in the Sun's interior results from the fact that the mass of helium is not equal to the mass of the 4 protons that produced the helium.
True
53
True or False: The magnetic fields in sunspots can be detected by the fact that some lines in the spectrum of a gas split into two or more lines by the action of magnetic fields.
True
54
True or False: According to the ideal gas law, the only way to have high pressure is by having a high density.
False
55
True or False: Comparison of the number of sunspots and the surface temperature of the Earth shows a correspondence right up to the present day.
True
56
True or False: The Sun converts mass to energy through the proton-proton chain.
True
57
True or False: The convection zone constantly cycles fresh hydrogen into the Sun's core and moves created helium into the outer parts of the star.
True
58
True or False: The mass of an entire hydrogen atom is converted into energy during the proton-proton chain.
False
59
What is the photosphere?
The Sun's surface, where any photons created can freely escape into space.
60
Where do thermonuclear reactions convert hydrogen into helium, generating immense energy?
In the core
61
What is the radiative zone?
Where energy moves outward via photon radiation.
62
What is the convection zone?
Where heat is transported through gas movement.
63
How long do photons created in the Sun's interior take to diffuse to the surface?
16 million years
64
What is granulation in the context of the Sun?
The surface of the sun is not one smooth color, but is due to convections and reactions happening underneath.
65
What does hydrostatic equilibrium in the Sun refer to?
The balance between the inward force of the Sun's own gravity and the outward force arising from the Sun's internal gas pressure.
66
What is Einstein's Equation?
E = mc^2 (Energy = Mass x Speed of light^2).
67
In nuclear reactions, what is produced when nuclei are combined together?
A completely new element.
68
What causes solar winds?
The Sun's magnetic field.
69
What are dark spots on the Sun?
Cooler areas due to stronger magnetic fields within them.
70
Why do sunspots happen periodically?
They get smaller with time until they close, as the area that caused it will be slowly recovering.

ch.1 astronomy (15 decks)

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