Astronomy - Ancient Genus, Modern Dilemmas - Note: Assignments are taken from Seeds, 8th Edition
You might want to check the Astronomy
Picture of the Day.
syllabus
First assignment:
In the text, read all of chapter 1. Answer questions 1, 4 and 7. Do problem
2.
Begin the first lab assignment. This lab may be done anywhere. If you need help
with the lab you may attend the scheduled lab sessions in Bowman 107. The purpose
of this lab is to give you a sense of the scale of the universe (or at least
our small part of it). For details on the lab click here.
Look for the planet Mars in the evening sky - it's up most of the night. Mars,
if you've been aware at all, was at its closest to Earth at 4:30 UT on the evening
of 25 August. We will look at it with our telescopes as the weather permits,
perhaps 2 weeks after its closest approach. Question: I was asked if it would
still be bright enough to be worth looking for - how much less bright will it
be two weeks later than 25 August? (For an answer to this question, click here).
Second Assignment:
In the text, read all of chapter 2. Answer questions 2, 11 and 12. Do problems
3 and 5. More on the materials covered in the chapter can be found here.
Third Assignment:
Begin the second lab assignment. Like Lab #1, this may be done anywhere (this
lab assignment takes one month to complete). Record the progression of the Moon
during one lunar cycle. To do this, start at any convenient time (10 September
would be a likely choice, because the Moon is full that night. In this case
the Moon rises as the Sun sets). The idea is to chart the location and phase
of the moon through one lunar cycle. To do this, record the Moon's shape and
position (i.e. height above the horizon or some other landmark), and the time
of your sighting. The following night repeat your observation and take new data
on position, time and shape (draw some pictures). Continue for one lunar month.
Notice that if you decide to look for the Moon at the same time every night,
it will move across the night sky and eventually not be visible at that time.
on the other hand, if you look for it at the same location each night, you will
find yourself taking measurements at odd and sometimes inconvenient hours (such
is the lot of astronomers). A combination of these two approaches early into
your experiment will allow you to predict when your next observation should
be. This is the object of the exercise - to be able to predict where the Moon
will be at any time during its cycle, and to know what part of its cycle the
moon is in whenever you see it in the sky (day or night).
Fourth Assignment:
In the text, read all of chapter 3 (much can be gained by understanding the
various drawings). Look at the box about small angles on page 32, and ask me
to discuss it in class. Answer questions 1, 3, 9 and 11. Do problem 6. For a
picture of a solar eclipse, click here.
Fifth Assignment:
Read all of chapter 4. Answer questions 3, 7, 8 and 12. Do problems 4 and 6.
Here are some references on early astronomers: Of
all the motions there were, motions of the heavenly bodies most occupied the
thoughts of ancient thinkers. The Pythagoreans
put Earth at the center of the universe and the planets (including our Sun and
Moon) on spheres turning around it. Variations of this model were proposed (most
notably by Aristarchus
in about 200 BC), but the matter was essentially settled by Plato
when he posed the problem of finding the best combinations of circular orbits
to explain the motions of the planets. The most successful attempt was by Claudius
Ptolemy in about 100 AD. Using the idea of epicycles proposed by Hipparchus
over 200 years earlier, he created a complex model (the Ptolemaic
system) that could predict the motions fairly accurately - Plato's problem
had been solved. The Ptolemaic system was accurate enough (although modified
- and made more complex - over time) to stand for fifteen centuries until, looking
for a simpler way, Nicolaus
Copernicus moved the center of the World to the Sun.
of
Galileo Galilei was a major contributor to the Copernican Revolution.
He was born in Pisa, Italy in the same year as Shakespeare, on the day that
Michelangelo died: 1564. He died in 1642, the year Newton was born.
Sixth Assignment:
Read chapter 5. Note that the most important characteristic of a telescope is its ability to gather light, and this is directly related to the area of the objective lens or mirror (or the dish, for a radio telescope). As the area of an objective varies as the square of its diameter (do you know why?), doubling a telescope's diameter increases its light gathering power by four times. For an overview of telescopes, click here. Answer questions 4, 7, 12 and 15. Do problems 1, 3 and 7.
Seventh Assignment:
Read chapter 6. Answer questions 2, 3, 6 and 7, and do problems 1 and 4. For a brief history of the discovery of atomic properties, click here. To get back to this page, use the back button on your browser.
Eighth Assignment:
Read chapter 7, answer questions 2, 11 and 14. Do problems 6 and 7. For some general information on the sun, try this link.
Ninth Assignment:
Read chapter 8. We've already discussed the stellar magnitude scale. Understand how we use parallax to measure the distances to nearby stars, and how stellar brightness is measured by magnitude numbers. These two pieces of information (distance and apparent brightness) allows us to know the true (absolute) brightness - and so energy output - of stars. Read about the different types of binary stars. Most important is the H-R diagram. We will talk about it in class. Answer questions 1, 3, 7, and 12. Do problems 1 and 2.
Tenth Assignment:
Read chapter 9. Again, pay attention to the H-R diagrams. Read the materials on the interstellar medium. The one most important characteristic of a star is its mass. Everything about its evolution and eventual death depends almost exclusively on its mass. Answer questions 1, 2, 9 and 10. Do problem 2.
Eleventh Assignment:
Read chapter 10. Play attention
to the relation between a star's mass and its eventual end. Answer questions
1, 3 and 10. Do problems 7 and 9.
On the 8th of this month there will be a total eclipse of the Moon, visible
from our location. Look on the Internet for exact times. As a laboratory assignment,
you are to observe the eclipse (weather permitting, of course), and record the
event. A camera (video, digital or film) will be a useful tool. This will be
one of the shorter eclipses on record, but it still will occur over an extended
time, with totality lasting about half an hour. Both Saturn and Mars will be
near the Moon during the eclipse. This type of alignment always prompts responses
like the one found at http://www.emediawire.com/releases/2003/11/prweb87243.htm.
check it out and bring your thoughts about it to class.
Twelfth Assignment:
Read chapter 11. Neutron stars and black holes are among the more exotic objects in the sky. Black holes are especially popular in the press. Understand what they really are, and how they are formed. Answer questions 2, 3, 13 and 14. Do problems 1 and 4.
Thirteenth Assignment:
Chapter 12 covers the Milky Way galaxy in considerable depth. Read sections 1 and 2, and section 4. (You may have to refer back to earlier parts of the chapter). Skim the rest of the chapter, but don't try to remember all the details. You should come away with a good understanding of the character of our own galaxy. Know how the 21 cm. radio signals help map the spiral arms, and so the overall shape of or galaxy. Answer questions 3, 5 and 14.
Fourteenth Assignment:
Read chapter 13. The shapes and number of galaxies, and distances to them using the Hubble law are worth remembering. Black holes at galactic centers and the existence of dark matter are current topics of active research. Notice how galaxies can collide, but stars never seem to. answer questions 1, 7, 9 and 10.
Fifteenth Assignment:
Read chapter 14. Most of what's in the first section is contained on pages 280 and 281. Read section 2 about the history of quasars, and about relativistic red shift. The mathematical details are not important, just that the result is that these objects are very far away indeed. answer questions 1, 8 and 11.