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Astronomy
A Beginners Guide to the Universe
43
Astronomy
Undergraduate 1
11/07/2010

Additional Astronomy Flashcards

 


 

Cards

Term

 

 

 

What is the closest star to Earth after the Sun and how many light years away is it?

Definition

 

 

Alpha Centauri

4.3 light years away

Term
List the overall structures of the sun starting from the center
Definition

Core

Radiation Zone

Convection Zone

Photosphere

Cromosphere

Transition Zone

Corona

Solar Wind

Term
Which one of the structures of the sun is the visible "surface" of the sun?
Definition
The photosphere
Term
What is the sun powered by?
Definition

Nuclear Fusion

(a process by which two or more nuclei combine and realease energy)

Term
What is the radius of the sun and how many times larger is it than that of the Earth?
Definition
THe radius of the sun is about 700,00 km and is 100 time greater than the Earth.
Term
How long does the sun take to rotate as measured at its equator?
Definition
25.1 days
Term

What is it called when we measure how much solar energy is received per square meter of every second on the earth?

 

What is that quantity?

Definition

Solar Constant

 

1400 watts per square meter

(W/m2)

Term

What is it called when we calculate the total amount of energy radiated in all directions from the sun?

 

What is the sun's _____?

Definition

Its luminocity

 

3.86 X 10 (26th) W

Term
What is it called when the sun's pressures outward push exactly counteracts gravity's inward pull?
Definition
Hydrostatic equilibrium
Term
What is it called where researchers have constructed a mathematical model of the sun?
Definition
Standard Solar Model
Term
What is the sun's surface temperature
Definition
5780K
Term
What is the sudy of solar surface patterns called?
Definition
Helioseismology
Term
What is the region of the sun's surface where virtually all light is emitted?
Definition
Photosphere
Term
What region of the sun is where nuclear reactions generate energy?
Definition
The core
Term
What are the two distinct ways that energy is transported from the sun's core to the photosphere?
Definition
Convection and Radiation
Term
What is the name of the observatory that was launched in 1995 by the European Space Agency?
Definition

SOHO

Solar and Heliospheric Observatory

Term

What is the name of the point where SOHO is stationed and why is it stationed there?

 

How far is this point?

Definition

L1 or Lagrangian point

It is at this point where the gravitational pull of the earth and sun are the same

 

1.5 million km

Term

The visible surface of the sun is mottled with regions of bright and dark gas known as _______?

 

 

About how far aross are each of them?

Definition

Granules

 

(THe direct granulation of the solar surface is a direct reflection of motion in the convection zone)

 

THey are about 1000 km across

Term
What is the flow pattern quite similar to granulation, material upwells at the center of the cells, flows across the surface, thew sinks down again at the edges
Definition
Supergranulation
Term
The __________ of a sunspot simply indicates which way its magnetic is directed.
Definition
Polarity
Term

What is an umbra?

What is it surrounded by?

 

 

 

 

 

 

 

 

Definition

The dark center of a sunspot.

The outer grayish part called a penumbra.

Term
All the sunspot pairs in the same solar hemisphere have the same magnetic configuration. T or F
Definition
True
Term

What causes constant stretching, twisting and folding of magnetic field lines?

 

Definition
The sun's differential rotation and convection
Term

What is a solar cycle?

 

Definition
THe period needed for both the average number of spots and the suns overall magnetic polarity to repeat themselves.
Term
What are active regions?
Definition
When the photosphere erupts violently spewing forth into the corona large quantities of electrical particles.
Term

What are prominences?

 

Definition
Loops or sheets of glowing gas ejected from an active region on the solar surface
Term

What are flares?

 

Definition
Another type of solar activity observed near active regions.
Term
What does an active prominence measure to?
Definition
100,000 kms
Term

What is a coronal mass ejection?

 

Definition
A giant magnetic bubble of ionized gas which separates from the rest of the solar atmosphere and escapes into interplanetary space
Term

What are coronal holes?

 

Definition
Vast regions of the sun's atmosphere where the density is about 10 times lower than the already tenuous normal corona
Term

Why are coronal holes lacking in matter?

 

Definition
Because the gas there is able to stream freely into space at high speeds driven by disturbances in the sun's atmosphere and its magnetic field
Term
What is the process of nuclear fusion?
Definition
The combining of light nuclei into heavier ones
Term
What is the law of conservation of mass and energy?
Definition
States that the sum of the mass and energy must always remain constant in any physical process
Term
What is most common and lightest element in the universe?
Definition
Hydrogen
Term
What is the next lightest element after Hydrogen that powers the sun?
Definition
Helium
Term
What is a deuteron?
Definition
A form of hydrogen with an extra neutron in its nucleus.
Term
What is a positron?
Definition
Atomic particle with properties identical to those of a negatively charged electron, except for its positive charge. The positron is the antiparticle of the electron.
Term
What is a neutrino?
Definition
A chargeless and virtually massless particle that is one of the producers of fusion reactions in the sun.
Term
Strong neuclear force
Definition
Short range force responsible for binding atomic neuclei together. It is the strongest of the four forces of nature.
Term
Weak neuclear force
Definition

Short range force weaker than both electromagnitism and the strong force but much stronger than gravity.

 

Responsible for certain neuclear reactions in radioactive decays.

Term
Proton-proton chain
Definition
The chain of fusion reactions leading from hydrogen to helium that powers main sequence stars.
Term
Solar neutrino problem
Definition
Discrepancy between the theoritacally predicted flux of neutrinos streaming from the sun as a result of fusion reactions in the core and the flux that is actually observed
Term
Neutrino occillations
Definition
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