Astronomy Fourth Test Flashcards
27- a) Describe the solar wind, including its composition, range of densities near Earth, and how long it takes to get to Earth.
a) Solar wind is a stream of charged particles (mostly protons p+ and electrons e-) that the sun emits that travel from it through the solar system. It takes them 2-3 days for them to get here, their density around earth ranges from 1-15particles per cm^3.
27b) Explain briefly why we can receive am frequency radio signals from far away at night.
b) Solar wind particles compress the ionosphere of the day side of the earth, meaning that the night side is always larger. The ionosphere is the medium that AM radio travels best through.
29- a) In your own words, state the 2 principles of special relativity.
29a) 1.The laws of physics are the same in all inertial frames of references.
b) 2. The velocity of light is the same for all observers``
29b) Describe the effects on space, time and mass that result from these principles, including the mathematical form of the Lorentz factor.
29b) The mathematical form of the Lorentz factor is 1/ sq (1 - v^2/c^2.) Using this equation to describe objects moving through space, one can see that as an object’s velocity approaches the speed o
30- The Michelson-Morley experiment helped lead to the theory of relativity.
a) What were they attempting to investigate?
30a) They were looking for the aether, the medium that light was thought to pass through. They were detecting it by splitting a beam of light and looking for phase interference when they recombine. They didn’t detect it, instead the results of their experiment suggested that the speed of light is the same for any observer.
30- The Michelson-Morley experiment helped lead to the theory of relativity.
a) What were they attempting to investigate?
30a) They believed that light coming at Earth would have to travel through the luminous aether, meaning it would slow down by .000001 (CHECK)… i don’t understand this.
30b) Draw a 2-dimensional space-time diagram using the x (horizontal) and time (vertical) dimensions as the axes, of light moving to the right and light moving to the left, passing through x=0 at time t=0.
30b. Just draw the x. Light cone! x
31- a) Draw a diagram of a star showing and labeling the various layers that astronomers recognize. Indicate which layer is seen as the visible surface, where spectral absorption lines are formed and where hydrogen fusion occurs.
31a) Diagram of star… layers core, interior, photosphere, chromosphere, corona. Visible surface is photosphere, spectral absorption in in chromosphere, hydrogen fusion in core.
32b) If a star is 1 parsec away, what is the difference between its absolute magnitude to its apparent magnitude? (The numbers may be different on the test.)
b) For some reason, a star at 1 is 100x brighter than the same star at 10. why? IDK.
So the question is what mag difference makes a 100 difference. 2.521^x = 100;
do the log or whatever and get 5: 5 difference in magnitude.
32b) What is the distance in parsecs to a star of parallax angle 1/100 second of arc? Approximately what is that in light years. (Numbers may be different on the test.) c) Not posted in advance.
Parsecs = 1 / arcsecs. 1/ .01 = 100 parsecs, 300 lightyears.
32- a) Draw a diagram illustrating how a basic photoelectric photometer works.
a) Just draw the battery.
