astronomy homeworks ( Astronomy of the Universe AST 101) !!

1) Components of the electromagnetic spectrum. Radios waves (long wavelength) through gamma rays (short).

2) Components of visible light. Red (long wavelength) through violet (short wavelength).

3) Know that longer wavelength is lower energy.

4) Know the difference between energy and intensity for light.

5) Know the difference between longitudinal and transverse waves. Know that light is a transverse wave.

6) Know the three types of spectra and what causes them.

a. Continuous

b. Emission

c. Absorption

7) Know that emission and absorption spectra are used to determine the composition of what is being observed.

8) Know that a prism works by changing the speed of light as it passes from one medium to another. Know that this causes a change in direction for the light and that this deviation is dependent on wavelength. This is how a prism breaks the light apart into its various colors (wavelengths).

9) Know why it is important to assume that the laws of physics are the same everywhere (allows for comparison). Know the consequences of this as far as particles and molecules are concerned (all protons must have exactly the same properties, in fact all similar particles and molecules must have the same properties).

10) Understand that the universe wants to be stable and wants to do things using as little energy as possible.

11) Know that when charged particles interact and release energy that the energy will be in the form of photons. This is interpreted as the photons carrying the information about the electromagnetic force.

12) Know the first four transitions by name, how they are categorized, and what type of photon is given off by each.

13) Know what causes a redshift and what causes a blue shift. Know that this is a property of light being a wave and is a specific example of a Doppler shift. Remember that if light is redshifted that does not mean that it is red in color.

14) Things to know about observing that all of the galaxies are redshifted:

a. This means that they are getting further away

b. This introduces the difference between classical redshift and cosmological redshift via the uniform expansion model

c. Remember that with cosmological redshift nearby objects are moving away slowly while distant objects are moving away more quickly

d. Know the definitions of classical and cosmological redshift

e. Be able to discuss in very broad terms what it means when we say that the universe is dominated by cosmological motion but there is still classical motion

f. There is still observable classical motion because all objects at the same distance do not have exactly the same redshift. This means there is a variance due to the classical motion.

15) Things to know about background radiation

a. Know that this was discovered accidentally by detection of low intensity background microwaves coming from very far away (further than anything else observed)

b. Know that this is a consequence of the universe changing from being opaque to being transparent

c. Know that this is expected if the Big Bang Theory is correct

16) Things to know about quasars

a. They were discovered by overlapping visible light maps with radio light maps

b. They were thought to be stars but the high redshift required further study to see if it was classical or cosmological

c. These objects are thought to be forming galaxies

d. Know the consequence of the nearest quasars being over two billion light years away

e. Know the difference between QSR and QSO

f. Understand that as the galaxy evolves and stabilizes the outer region will calm down first. This is lower energy and so the radio waves disappear first

17) Things to know about galaxy and star formation

a. They are basically the same process on a different scale

b. Debris is collapsing and the rotation rate is being amplified

c. This causes a large object (supermassive black hole for a galaxy or a star) to form at the center with a debris field around it

d. The debris field starts out spherically shaped and then flattens out into a disk

e. The disk in galaxy formation becomes the stars and the disk in star formation becomes the planets, moons, etc.

f. Know how and why a plasma core forms at the center of a star

g. Know that stars form inside a molecular cloud

h. Know what is meant when we say that density fluctuations trigger the star formation in a molecular cloud

18) Things to know about star evolution

a. Nuclear fusion is taking place in the core

b. The first element to fuse is hydrogen and the result of this fusion is helium via the proton-proton chain

c. Know the three steps of the proton-proton chain

d. Know that the core will not be able to support hydrogen fusion indefinitely and this leads to the hydrogen fusion moving outward away from the core

e. Know why this causes the star to get bigger

Roughly 35 of the test will come from topics 1 through 13

Roughly 37.5 of the test will come from topics 14 through 16

Roughly 27.5 of the test will come from topics 17 and 18