Astronomical Terms & Models

Models:

1. The Milky Way Galaxy (Top & Side Views)

a. Know location regions for Pop I and Pop II stars

b. Size of Milky Way is roughly 100-120 thousand light years

c. 3 spiral arms

i. Earth is located on the far end of the middle upper arm

ii. Solar system is roughly 26,000 light years from the center of galaxy

d. The bulge is in the center--arms extend out from bulge (This is the disk)

e. Globular clusters exist all around the galaxy.

f. Halo envelops the disk

g. Corona envelopes the Halo

h. Milky was is roughly 13 billion years old

i. The mass of the Milky Way is roughly 10^11 Mass of the Sun.

j. There is believed to be a maxi-black hole in the center of the bulge

i. About 3 million times more massive than our sun.

k. There is believed to be dark matter between the Halo and the Corona

i. Dark Matter may account for as much as 95% of the galaxy's mass

2. The internal structure and crust of the earth.

a. Inner Core

i. 95% iron, 5% nickel

ii. Solid

b. Outer Core

i. Molten

ii. Same composition as inner core

c. Mantle

i. Hot rock

ii. Moves

iii. Convective zone

1. Like that of the Sun, but much slower

2. Lava like material

d. Crust

i. Thinnest on the ocean floor (5 miles)

ii. Thicker underneath continents (15-20 miles)

v Composition of the Earth was devised by studying seismographs from earthquakes as well as underground nuclear testing (rare today) as well as underground mining.

e. Source of magnetic field is the spinning of the inner core

f. Plate motion: The tectonic plates move about 2-3 inches a year

g. Pangaea: The super continent, one forms roughly every 500 million years.

1. The internal structure and atmosphere of the Sun.

a. Internal

i. Core

1. Furnace of the Sun

2. Transform H into He

3. Only about 1% of all H turns into energy

a. Very inefficient, but massive enough to burn for about 13 billion years

4. Core started 75% H and 25% He

a. Now about 50/50

5. Core temperature is about 15 million degrees

ii. Radiative Zone

1. Gamma rays are broken down (degraded) into other forms of light (X-rays, visible light, infrared, ultraviolet).

a. FYI, gamma rays come from inside the core.

b. It takes about Ð... million years for a gamma ray released from the sun to get to the surface

iii. Convection Zone

1. At the top of the radiative zone

2. Granules go down here once they burst on the photosphere and get reheated

3. "Boiling and mixing" takes place here.

b. Atmosphere

i. Photosphere

1. Surface of the Sun

2. Gaseous

3. Most visible light comes from the photosphere

4. 5,700 degrees

5. Rice grain appearance

6. Center is hotter, outside is redder

7. 864,000 miles in diameter

ii. Chromosphere

1. Directly above the photosphere

2. Inner atmosphere

3. 10,000-20,000 miles thick

iii. Corona

1. Outer atmosphere

2. Inner corona is about 1 million degrees

3. Outer corona is about 3 million degrees

a. Outer corona is almost a vacuum

iv. Sunspots: Most sunspots have structure

1. Umbra: Inner darker part of spot

2. Penumbra: Outside part of spot, redder

v. Flare

1. Bright patches on the Sun

2. Most energetic event on the Sun

a. Flare= 100,000 nuclear weapons time 1 billion

vi. Granulation

1. Textured, rice grain appearance of the sun.

2. Granules are like cells or bubbles of gas

3. Rise to the surface, blow after 10-15 minutes

4. Sink to convective zone to reheat, cycle repeats

vii. Prominence

1. Spiral cloud of gas

2. It is an explosion on the surface

viii. Spicule

1. Mini prominence

3. Nebular theory for the formation of the solar system.

a. Size: 2 light years across

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