First time:

• Print entire Frame (ca. 16 pages);
• then "Select All", "Copy" (Ctrl-c) and "Paste" (Ctrl-v) it into a Word processor document.

Guidelines for Homework:

• Assigned HW must be handed in on or before the deadline (if you're not permanently late, a few days late is okay too).
• Write clearly or type.
• Essay questions should be answered in no more than 2 to 3 sentences in your own words (don't copy information from other web sites unless you're asked to do so).
• However, when asked to access a web site, copy (highlight and Ctrl-c) and paste (Ctrl-v) a paragraph (not more than one) from the appropriate web site along with the URL (Location - web address).  (I put this in bold and italics because students regurlarly forget this and get docked down.)  I have compiled a list of web sites (links) on my homepage and feature links to other lists.  I advise you to make your own list by pasting web addresses into a Word processor document.
• Before getting too frustrated over assignments, contact me in time (not an hour before it's due)!  This holds for download times being too long, tough questions, etc.  Seek help from me!

Post something interesting about astronomy on the bulletin board.  I will denote this as SP and it would count as your first lab on the grade sheet.  This is what I like you to post: come up with something interesting about astronomy that you know or read about.  These short postings (perhaps two paragraphs) can be about anything in astronomy (planets, stars, comets, galaxies, eclipses, moons, astronomy stories and mythology, etc., even astrology).  Examples: I had a student explain a cowboy could tell time at night by observing the Big Dipper and then waking up another guy for the next shift; somebody else explained why the starfinder (that you purchased) has East on the left and West on the right; and yet another student explained why our Sun would trail backwards for a short time if she was standing on Mercury.

Becoming familiar with the Internet   (15 points)

Copy the relevant information from appropriate web sites and copy the URL (web address) as well.  (You need to right-click into the frame (of the other web site), then "show info", then highlight and copy (CTRL-C) the relevant web address.)
Disclaimer: this procedure is permitted for questions regarding web sites.  For all other questions (and these are the majority) this is not okay.  Instead, answers must be written in your own words.

1. Find information on Mercury's atmosphere.
Hint: Click on the "Astronomy web sites" on my home page, then choose one of the planet lecture web sites.


2. How can the mass of stars be determined?
Hint: Via Kepler's 3rd law. I advise a search on google.


3. Which types of telescopes are there?
Hint: Why don't you try http://www.telescope.com/default.asp in their online catalog under Helpful Info? Or you check my (A. Veh) lecture on telescopes .

Star Gazer
Virtual Reality Moon Phases or Stardate
Solar images
Yahoo's Astronomy pages
Sky & telescope's Interactive Skycharts 

Using your starfinder while watching the night sky,  memorize where the following constellations are:
Fall:  Ursa Major, Scorpius, Sagittarius, Cygnus, Hercules, Bootes, Corona Borealis, Pegasus.
Spring:  Ursa Major, Cassiopeia, Orion, Canis Major, Auriga, Taurus, Gemini, Pegasus.  (no points)

Access the “Ask the Astronomer” homepage at http://www.astronomycafe.net/ , this might be a good resource for your questions (include an article from the web site in your homework). (5 points)
(Copy and paste a paragraph (not more than one) from the appropriate web site along with the URL.)

Gravitation and Motions in the Solar System (15 points)

1. Write these numbers in scientific notation (the exponent is preceded by a ^ or raised):  Examples:    100 = 10² = 10^2; Gravitational constant G = 0.000 000 000 066 7 = 6.67 × 10 ^-11 = 6.67 × 10^(-11) .
Your turn:  1000;  1,000,000; speed of light c = 300,000,000 m/s; one lightyear 5,860,000,000,000 miles;  0.001; wavelength of yellow light 0.00000055 m
(Hint: check under scientific notation and in the Appendix of your textbook at Constants.)

2. a) Explain how one measures distances to planets (in our solar system) or near-by stars using triangulation (parallax).
b) Why is it difficult to measure accurate distances?

3. a) What actually is the morning “star”?
b) What actually is a falling “star”?
c) What actually is a “planetary” nebula?
d) Why did people (astronomers) invent these names, although they turned out to be inaccurate?

4.  What is the ecliptic?
 a. A band of constellations through which the planets and our Sun appear to move.
 b. The line that our Sun traces across the celestial sphere.
 c. The extension of the Earth's equator on the celestial sphere.
 d. The cycle of lunar phases.

5.  What is the zodiac?
 a. A band of constellations through which the planets and our Sun appear to move.
 b. The line that our Sun traces across the celestial sphere.
 c. The extension of the Earth's equator on the celestial sphere.
 d. The cycle of lunar phases.

6.  Where on the celestial sphere would you look for the planets?
 a. On the celestial equator.               b. On the Galactic equator.
 c. In the zodiac (near the ecliptic).   d. At the north celestial pole.

7.  If you see a bright "star" in the sky, how could you tell whether it is a star and not, for example, Venus?
 a. Venus is greenish in color.
 b. You cannot see Venus from Earth.
 c. Planets always appear right next to our Moon.
 d. Look at it several days later - if it's a planet, it will move across the background stars.

8.  What is meant by "angular diameter"?
 a. An object's diameter.                    b. The angle between the two sides of an object.
 c. The distance around an object.   d. The angle between two circular objects.
 
 

Access this site to get latitude and longitude for your address: http://www.mapblast.com/ (if you don't feel like registering, go to indo.com at http://www.indo.com/distance/).  Then go to http://www.heavens-above.com/ , type in your latitude and longitude, finally print out a 7-day prediction table for Iridium flares and try to observe some.  (10 points)
(Copy and paste a paragraph (not more than one) from the appropriate web site along with the URL.)

Try NASA's satellite tracking applet as well (no points) : http://liftoff.msfc.nasa.gov/realtime/jtrack/Spacecraft.html
Warning: download times can be very long! But you'll love it once it's running.

Telescopes  (20 points)

1. a) Why do astronomers want to work with larger and larger telescopes?
b) Why are the largest telescopes in the world reflectors?

2. Name the three powers of a telescope in order of importance and on what they depend.    (Check my telescope lecture.)

3. a) What are the advantages of having many of the world's largest telescopes atop Mauna Kea on Hawaii and several Chilean mountains?
b) What would be practical disadvantages for astronomers (not telescopes) on even higher mountains?

4. a) Which parts of the electromagnetic spectrum can be observed from the ground?
 b) Name five space telescopes and at which wavelengths they observe.  (Hint: one of the above web sites might help.)
 c) The Hubble Space Telescope (HST) is observing at visible and near-infrared wavelengths.  What is the advantage of having Hubble in space?  (Hints: it's not the largest telescope, and your answer should be related to parts of question 2 and 3)

Solar System

5. Give a brief description of the contents of our solar system.  What do you find in interplanetary space?

6. a) Name the terrestrial and Jovian planets.
b) Name five differences between the two groups.  (Hint: it's instructive to study my peculiar planets script.)

7. a) How did the solar system originate?
b) How did recent discoveries upset the theory that rocky planets form close to their Sun and gaseous planets far out?  c) Do astronomers know a way out?
 

Bonus: start making a list of current events in Astronomy and Spaceflight.  Due at the end of the semester.  (Points depending on effort.)

Access Arny's home page (http://www.mhhe.com/arny) and the web site of an observatory (Check the list of my telescope links). (10 points)
(Copy and paste a paragraph (not more than one) from the appropriate web site along with the URL.)

I really urge you to do this homework together in groups of two!

Gravitation and Motions in the Solar System  continued (40 points)

1. Explain the reasons for the seasons: what two conditions relating to the Earth's position and motion in space cause what two conditions of our Sun's appearance as seen from the Earth's surface?
 (I apologize that the question sounds so complicated.  I've been trying hard to make it sound easier, but every time I did, I would always give part of the answer away.  So ask me in class to clarify the question.)

2. Kepler:  a) When 2 stars are orbiting each other (Algol in Perseus and its companion for example), do they also obey Kepler’s laws? Explain.  b) Which equation are astronomers using to determine the mass of planets, stars, galaxies, etc.?  c) What do astronomers have to observe about an orbiting object in order to use the modified form of Kepler 3?  d) Assume there is a planet 100 times farther away from our Sun than Mercury (which is at 0.39 A.U. and needs 88 days for one orbit), how long would it take this planet to orbit our Sun?  (Hint: cube 100, take the square root of the result and then multiply by 88 days.)  e) What is the name of this planet in our solar system?

3. Retrograde Motion:  What causes retrograde motion?

4.  Explain Newton's 3 laws in terms of what could happen to the motion of a slowly moving boat holding you and a paddle in a lake, e.g. what could you do with the paddle that would have to do with Newton's laws?

5. Newton's Law of Gravitation:  a) Do you and the paper on which this homework is written, respectively the computer screen in front of you, gravitationally attract each other?  Why?  b) Do a baseball thrown into the air and the Earth attract each other?  Why?  c) Why does it seem that the Earth is not falling towards the baseball?  Explain.  d) Why would a baseball go higher if it were thrown upward from the surface of our Moon?

6. Phases of our Moon:  a) How much of our Moon is lit up at any given time?
 b) How much of this lit-up half do we see during a new moon?
 c) Why do we see different phases of our Moon?

7. a) Explain eclipses.  b) Solar and Lunar Eclipses:  Why do eclipses occur only every 6 months?  c) Find a web site(s) that features a listing of upcoming solar eclipses including the regions on the earth where the eclipses are visible.

8. Tides and tidal forces:  If the East coast of the United States has a high tide, where on Earth would you find low tides and where the other high tide?  (Check a globe or atlas.)
 

Access Bill Arnett's The Nine Planets at http://www.seds.org/billa/tnp/ .  On google, search for the Coriolis effect.  Find a website that illustrates (i.e. photos or drawings) the Coriolis effect. (10 points)
(Copy and paste a paragraph (not more than one) from the appropriate web site along with the URL.)

Earth-Moon and terrestrial planets     (20 points)

1. Would our Moon be a good place to put a telescope there?  (Hint: try "lunar telescope" on google.com)
 a) No, because it is too close to the Earth and light reflected from the Earth interferes with the darkness of the lunar skies.
 b) Yes, because our Moon lacks an atmosphere.
 c) No, because people can not survive for long on our Moon.
 d) Yes, because lunar soil contains glass, which is useful in the construction of telescope mirrors.
(Hint: on yahoo or google, type in lunar telescope .)

  2. Which of the following spacecraft did not visit Mars?
 a) Viking
 b) Surveyor
 c) Venera
 d) Pathfinder

3. Venus is known to be an unusually hot planet; however, what part of Venus is so hot?
a) Venus has a very high temperature, molten core.
b) For reasons still not understood, Venus has an unusually hot, molten mantle that has given rise to vast numbers of volcanoes.
c) The atmosphere and surface are unusually hot.
d) The crust of Venus is mostly molten and has not cooled and solidified.

4. Name three significant surface features on Mars.

5.  A “stretching” or "bulging" produced on one object by the gravity of another object, the direct result of the dependence of the gravitational force on distance, is termed a  ______________  force.

6.  The astronomical unit (AU) is a unit of length equal to  _________________ .

7.  The rotation of Venus is exceptional because it is  _______________ .

8. ____________ is not completely mapped, simply because satellites didn’t pass over its entire surface.  _________ had to be mapped by radar because of its dense cloud cover.  ____________   has never been mapped because no satellite ever went by it, and it's also too far from us to take good pictures with telescopes on Earth.

9. Numerous phenomena are due to the motions of the Earth and our Moon relative to each other and to our Sun, and to their interaction through mutual gravitational attraction. Name the motion, etc. (e.g. rotation, orbit, gravitation, shadows, etc.) for each of the following.
 (a) the night-day cycle on Earth, (b) eclipses, (c) the seasonal cycle, (d) the Coriolis effect (check my lecture notes), (e) parallax, (f) lunar phases, (g) ocean tides on Earth, (h) the same face of our Moon always facing the Earth, (i) the difference between sidereal time and solar time, and (j) the Aurora.
 Example: (i) Earth's rotation on its axis -> sidereal time; Earth's rotation on its axis and its progression on its orbit during one rotation -> solar time
 Hints: charged particles - tidal lock - Moon's gravitation - geometry Earth, Moon, Sun - Earth's orbit - motion on rotating Earth - tilt of axis - nearly perfect alignment of Earth, Moon, Sun - rotation - shadows

10.  Why do the surface features of two representative terrestrial planets, Mercury and Earth, appear so different?

On the internet and in your book, compare (the spacecraft) Galileo images with Voyager images of Jupiter’s moon Io.  Then Hubble with Voyager images of Neptune.  What do you conclude from differences that you see in the images? (5 points)

Jovian Planets     (15 points)

1. Which of the following discoveries were made by Voyager 1 or 2?  (Several answers possible.)
 a) Jupiter has an encircling ring.
 b) Jupiter’s Great Red Spot is characterized by swirling circulations much like a terrestrial hurricane.
 c) Jupiter has cloud bands in its upper atmosphere.
 d) Jupiter’s moons are as varied as planets.

2.  This planet has such a low density that it could float in water.  It also gives off three times more energy (from its interior) than its absorbs from our Sun.
 a) Uranus.        b) Neptune.       c) Jupiter.       d) Saturn.

3.  Why are Saturn’s rings so bright?
 a) They are made of metallic hydrogen.
 b) They are made of icy particles.
 c) The particles in the rings are highly polished from numerous collisions with other particles.
 d) Saturn is so bright, the rings reflect a lot of light from both Saturn and our Sun.

4.  For which planet is it possible for our Sun to remain overhead for years at a time at either pole and for the equator to receive almost no sunlight for years?
 a) Uranus.        b) Neptune.       c) Pluto.         d) Triton.

5.  This planet was discovered due to a tremendous mathematical effort employing the fact that all masses act on each other gravitationally and therefore perturb each other’s orbits.
 a) Uranus.        b) Neptune.      c) Jupiter.       d) Saturn.

6.  Which moon orbits a planet that is about twice its own size (tricky: this is NOT a Jovian planet)?
       a) Charon.        b) Triton.        c) Titan.         d) Earth’s Moon.

7.  Jupiter’s rapid spin gives rise to its  ____________________   .

8.  Tidal forces are partially responsible for the existence of the   ____________   circling all big planets.

9.  The moon with active volcanoes is  ______ .

10.  Galileo discovered that Saturn had one permanent moon on each side (his telescope’s resolution wasn’t good).   ____________  discovered that these were rings.

11.  When we see Saturn’s rings edge-on, they seem to disappear.  We can thus conclude that the rings are _______________ .

12.  _____________ is the planet that William Herschel discovered by accident during his observational scans for stars.

Peculiar Planets (20 points)

1. If you were on  ______________ , you would see that daylight would last almost 3 months and that our Sun is backtracking (retrograde) at times.

2. You couldn’t survive on Venus because its atmospheric pressure is  _____ times stronger than on Earth, rain is ____________ and temperatures are sweltering due to the __________________ .

3. a) What is the shape of the Analemma (the equation of time)?
b) What time of the year marks the lowest point?  The highest point?
 c) Local noon can be off by as much as 20 minutes.  We say that a day lasts 24 hours and mean the time between one noon and noon on the following day.  We account for day and night by Earth’s rotation, which is 23h 56m.  What accounts for the remaining 4 minutes? (Hint: this doesn't have to do with neither the analemma nor the leap day/year.)

4. The highest mountain in the solar system is able to be 70,000 feet high (without crushing under its own weight) because _______ surface gravity is comparatively low.

5. _______________, between Mars’ and Jupiter’s orbits, probably weren’t able to accumulate into a planet because Jupiter’s tidal forces kept them from doing so.

6. ______________ four largest moons can be seen in a small telescope and when carefully observed over a few days, reveal that they revolve around this planet.

7. Two of ____________ moons are co-orbital but one being slightly faster because of _______________ law, and they switch orbits because their _______________ attraction is large during close encounters.

8. ______________ seasons would be extreme because its axis is tilted by 90 degrees.

9. The great blue spot on _____________ , discovered by Voyager 2 in 1989, has vanished.

10. ___________ and ___________ face each other with the same side on their 6 day orbit because they are __________ locked.  This planet has been the farthest from our Sun once again since February 1999 (until the year 2231 when Neptune will be farther out again).

Since Astronomy uses the Greek Alphabet quite a bit, I want you to become familiar with it.  E.g. the s-sigma in the Stefan-Boltzmann law, the l -lambda as wavelength, as star names: a Orionis = Betelgeuse, b Orionis = Rigel, z Orionis = Alnitak.
Transcribe the following from the Greek to the Roman alphabet (ours).  It's already in English, so you don't need to translate, but Transcribe .        (20 points)

Examples: Transcribe = Transcribe.
At this URL you will find the Greek Alphabet .
= At this URL you will find the Greek Alphabet .

Please note that our keyboards are not completely representing the Greek alphabet. I chose to transcribe letters in such a way: English "c" and "ch" are Greek "c-chi" , "q" and "th" are " q-theta" , "y" and "ps" are "y-psi" , "h" is "h-eta" (a short "e"-sound), "f" and "ph" are "f-phi", "w" is " w-omega" (an "o"-sound), "j" is "j-phi".

The following is an image, so it won't copy into a word processor.  You need to print it therefore.

The Greek alphabet:

Access NASA’s Cassini and its Galileo (the spacecraft) homepages. (5 points)
(Copy and paste a paragraph (not more than one) from the appropriate web site along with the URL.)

Moons, Rings, and Pluto     (15 points)

1. What is the source of Io’s volcanic activity, i.e. why is Io volcanically active?

2. What is the Roche limit?

3. a) What have we learned about Titan?
b) Why is the Cassini spacecraft on its way to Titan?

4. How were the masses and radii of Pluto and Charon determined?

5. How much larger would Saturn and its rings appear (than our Moon appears from Earth) if one could look from Titan through its thick atmosphere?  Do this using simple proportions:  Saturn is 35 times bigger than our Moon, its rings are 80 times wider.  Saturn is 3 times farther away from Titan than our Moon is from Earth.

6. What are the latest news on Europa’s surface?

Asteroids, Comets, Meteoroids (15 points)

7. a) Name the three famous comets of the past fifteen years (’86, ’94, ’97).  b) Explain why these attained fame.

8. How does the appearance of comets change when they come into the inner solar system?

9. Why are meteors, asteroids, and comets important to our understanding of solar system history?

10. Which scientific laws did NASA use in its spacecraft trajectory calculations to make sure that its spacecraft Galileo would fly near the asteroids Ida and Gaspra?

11. a) How is the comet Swift-Tuttle connected to the magnificent Perseids meteor shower each year around August 12?
b) What causes a meteor shower?

Access the Particle Adventure at    http://ParticleAdventure.org/  and go through the lectures on the atom.     (5 points)
(Copy and paste a paragraph (not more than one) from the appropriate web site along with the URL.)

Matter, Radiation, and Spectra     (15 points)

1. Light
 a) can travel through vacuum (sound can't).
 b) is also called "visible" light and only a small part of the entire electromagnetic spectrum.
 c) has very short wavelengths (between about 400 and 700 nm).
 d) and all other kinds of electromagnetic radiation travel at the speed of light.
 e) all of the above.
 f) answers a) and b) only.

2. Which kinds of electromagnetic radiation penetrate the Earth's atmosphere fairly easily?
 a) visible light.
 b) gamma rays.
 c) radio waves.
 d) x-rays.
 e) all of the above.
 f) answers a) and c) only.

3.  An _____________ spectrum is produced by a luminous, thin gas (e.g. an emission nebula).

4.  An _____________ spectrum is produced when light is allowed to pass through a thin, colder gas on its way to the observer (e.g. any star’s spectrum).

5.  Give four properties of any visible object in the universe that (meaning the properties) can be determined by spectroscopy.  Explain how each of them is determined.  Reflect on what you learned about analyzing spectral lines.  (Hint: what I'm looking for are stellar quantities such as temperature, luminosity, mass, rotation, luminosity class, radial velocity, proper motion, orbital velocity, position, composition, radius (size), distance.  But note that I included some that are not determined by analyzing spectral lines.)

6. a) What do the different types of electromagnetic radiation (from radio to gamma) have in common?  b) How do they differ?

7. How are those types of electromagnetic radiation observed which cannot penetrate the atmosphere?  Name these types as well.

8. How are absorption lines produced in a stellar spectrum?

Do the tour of our Sun at     http://www.astro.uva.nl/michielb/sun/kaft.htm
Go to the SOHO homepage :   http://sohowww.nascom.nasa.gov      (10 points)
(Copy and paste a paragraph (not more than one) from the appropriate web site along with the URL.)

Our Sun     (30 points)

1. Write down the net equation for nuclear fusion inside our Sun.

2.  Hydrogen comprises approximately ______% of our Sun’s mass.

3. The corona can only be observed during a solar eclipse because ...

4.  Solar energy is produced by the fusion of light weight hydrogen into the heavier atom ___________ .

5.  a) What physical characteristics change in our Sun over the 11-year solar cycle?  b) To what is this cycle apparently related?

6. Describe what happens to a parcel of solar energy from the time it is produced via nuclear fusion in our Sun’s core until it arrives at Earth.

7. a) As mass decreases in the proton-proton cycle, what does it change into?  b) Which world-famous equation is linked to this process? A calculation shows that each produced gamma-ray photon has about 1 million times more energy than an ordinary visible light photon.

8. a) Our Sun’s mass is about 2.0  10³⁰ kg (4.4 10³⁰ lbs).  How do we know this?
 b) Our Sun’s luminosity is 3.9  10²⁶ Watts.  How do we know ...?
 c)  Sun’s radius is about 700,000 km (450,000 miles).  How do we ...?
 d) ... density is 1.4 larger than that of water.  How do ...?
 e)  ... surface temperature is 5,800 K (10,000 F).  How ...?
 f) ... core temperature is 15 million K (24 million F).  How ...?
 g) ... lifetime is estimated at 10 billion years (of which 5 billion are still ahead of us).  How ...?

9. This is an exercise on exponents (there will be NO calculations on the final), so that you're familiar with very large and very small numbers as they pop up during lectures.  Find our Sun's mass and luminosity in your textbook.  Now confirm these using the following calculations.
 a)  Mass is determined by Newton’s general form of Kepler’s third law:   M = 4 p² a³ / (G P²)  .  Look up the gravitational constant G, Earth’s distance to our Sun “a” (1 A.U., must be in meters though) and period P (1 year, must be in seconds).  Deal separately with numbers and exponents!  Multiply and divide numbers (4, 3.14², 1.49³, 6.67, 3.15²).  Now: add exponent of “a” in the numerator 3 times, from that subtract the denominator’s exponents of G (minus a negative make plus) and twice the exponent of P. 
b)  Compute our Sun's luminosity using the Stefan-Boltzmann law, L = 4 p R² s T⁴ .  In your textbook's appendix find the Stefan-Boltzmann constant , our Sun's radius R in meters and its temperature.

 Help each other and ask me for assistance.

 b)  The solar constant S (write it down) is given in square meters (1 qm = 10 sq.ft., don’t need this conversion) at a distance of 1 A.U. (write down in meters) where Earth intercepts our Sun’s radiation. Our Sun’s total luminosity is computed by multiplying the solar constant with the area of this 1 A.U. sphere that engulfs the outgoing solar radiation.  Therefore L = 4 p S r^2. 

Find a website featuring research on stellar spectra.   (5 points)
(Copy and paste a paragraph (not more than one) from the appropriate web site along with the URL.)

Measuring the Stars      (15 points)

1. What is the difference between the absolute and apparent brightness of stars?

2. The surface temperature of stars can be determined by
 a) the star’s color.
 b) the star’s spectral type.
 c) the peak wavelength at which intensity is highest.
 d) all of the above.

3. Explain how stars are plotted on the Hertzsprung-Russell diagram.

4. What is the main sequence?

5. Why are star clusters important to astronomers interested in stellar evolution?

6. Estimate the life expectancy of these three Main Sequence stars:  a 0.2 solar mass (0.01 solar luminosity) red dwarf, a 1 solar M (1 solar L) yellow star, and a 10 solar M (1000 solar L) blue giant.  (Check my Stellar Evolution lecture’s Appendix.)

7. a) Which are the two main elements of any star?  b) Explain, how stars can have absorption lines from many different elements in their spectra.

Interstellar Medium  (10 points)

8. Describe the interstellar medium.

9. What are the roles of gravity, heat, and pressure in the process of stellar birth?  (Check my Stellar Evolution lecture.)

10. At what point does a protostar become a “living” Main Sequence star?

11. What actually is a lightyear?

What Information do we get from the Stars?   (20 points)
What Methods do we use to Evaluate these Data?
Which Conclusions do we draw?

Fill in the blanks in the table below.  Copies of the articles are supplied at the Sidney, Alliance, and Scottsbluff centers or are available by clicking on links inside the table.

Choose a Sky & Telescope or Astronomy issue (check at your library or on the web; indicate which) and fill in an entire row.  Check your local library for these magazines.  Scottsbluff's public library carries both, on the campus we have S&T , and I sent the March-June 97 S&T issues to Sidney and the June-September 97 and January/November 98 Astronomy issues to Alliance.
 
 

S & T   or Astronomy	Direct Information	Methods used to Evaluate Data	Conclusions
....	........	........	........
S&T 8/02, p.26	- faint points of light are moving over several months near Jupiter (paper doesn't mention their motion, but that's the only way they can be distinguished from fixed points)	- simple photography	- more moons of Jupiter are discovered
S&T 9/02 p.20	- radial velocity changes of the G8 star 55 Cancri	- analyzing its spectrum; not mentioned in the paper	....
S&T 3/02 p.20	....	- using Kepler 3 to determine the star masses of this binary star system	....
Ast. 1/99 p.28 & 30	....	- very subtle variations in the shape of these spectral lines	- "invisible" companions with Jupiter like masses -> more extrasolar planets  (see S&T, Ast. issues since fall of 1995)
Ast. 12/98 p.24	- photos and temperature data of  Phobos (Mars Global Surveyor)	....	- One meter (3 feet) deep dust layer on Phobos's surface
Ast. 11/98 p.26	- Supernova 1998bw (ESO), Gamma-Ray Burst (BeppoSAX, Compton), in same "patch" of sky	....	- "Hypernova", one possible explanation to the riddle of Gamma-Ray Bursts

Find a website featuring some kind of taxonomy or listing on Supernovae (Type I or II), Novae, Pulsars, or Black Hole candidates (either stellar or supermassive galaxy core).     (10 points)
(Copy and paste a paragraph (not more than one) from the appropriate web site along with the URL.)

Stellar Evolution, Death of stars, remains of stars  (15 points)

1. In a star cluster all stars were born at about the same time.  In a young cluster the most massive stars are beginning to die.  What happens to the least massive stars?  (Hint: check the Appendix of my stellar evolution script.)

2.  Comparison of HR Diagrams of young and old clusters confirms that  ________________  stars evolve faster.

3.  Stable stars are in a condition in which  ____________  is balanced by gas pressure.

4. In a Red Giant’s core gravity is balanced by
 a) Electron pressure (degeneracy).
 b) Pressure.
 c) Decaying Boron nuclei.
 d) Neutrinos.

5.  Starting with the element carbon, every other element (O, Ne, Mg, Si, ..., Fe and beyond) is higher in abundance (check SEA-7 ) than those in-between.  This is because these elements with an even number of protons Z keep fusing with the element  _______________ to produce elements with Z+2 (Red Supergiants and during Supernovae) .  “In-between” elements are formed by radioactive decay, fusion with some of the left-over Hydrogen (Red Supergiants) and neutron capture (Supernovae).

6. A small star, mainly composed of Carbon and Oxygen, shining away its stored thermal energy is a ______________ .

7.  The radioactive decay of Cobalt-56 affects the light curves of type-II supernovae about  ___________  after the initial peak luminosity.
a) 5 minutes
b) 4 days
c) 3 weeks
d) 2 months
e) 1 year

8.  Discuss how heavy elements, i.e. those beyond Helium (three cases: up to C and O; between C and Fe; beyond Fe), are produced.  Relate these processes to the types of stars in which they occur and to the evolutionary stages which result from these processes.  Example: Hydrogen fuses to Helium in all Main Sequence stars.
a) up to C and O: ....
b) between C and Fe: ....
c) beyond Fe: ....

9. What evidence is there hat many supernovae have occurred?

Stellar Evolution, Death of stars, remains of stars continued (15 points)

1.  A balance between gravity and  _________  is a factor which determines the interior structure of a star.

2.  The order of evolutionary stages of a star like our Sun would be Main Sequence, giant, planetary nebula, and finally  ___________ .

3.  The longest stage in the life cycle of a star is as a  _________________  star.

4.  A relatively common type of stellar outburst,  _________ , are believed to be the result of close binary systems in which matter from one star is dumped onto a companion.

5.  What causes a type-I supernova?
 a) The collapse of the core of a massive star.
 b) Mass transfer to a white dwarf in a binary where the Chandrasekhar mass is exceeded.
 c) A nova.
 d) The radioactive decay of cobalt into iron.

6.  ____________  are the most massive (Main-sequence stars), but are very short-lived, and found only in young star clusters.

7.  Massive stars eventually form cores of  _________ .

8.  The Crab Nebula supernova was observed to occur in the year  ________ .

9.  The Crab and Gum Nebulae are expanding clouds of gas (supernova remnants) created by a  ________________ .

10.  The glowing remains of a supernova explosion is known as a  ____________________ .

11.  Type II Supernovae explosions with a remaining core mass of less than 3 solar masses are believed to produce  ____________  as stellar remnants from intermediate mass stars.

12.  Type II Supernovae explosions with a remaining core mass of more than 3 solar masses are believed to produce  _____________  as stellar remnants from the most massive stars.

13.  Neutron stars spin at very fast rates measured in  ________________ .

14.  The mass of a black hole is theoretically predicted to reside in an infinitely dense ______________ at the center of the black hole.

15.  The spherical surface of space which defines the “surface” of a black hole is called the _______________ .

Find a website featuring the historical account of the explosion that lead to the Crab nebula.    (5 points)
(Copy and paste a paragraph (not more than one) from the appropriate web site along with the URL.)

Stellar Evolution, Death of stars, remains of stars continued (30 points)

1. What (spectral) types of (Main Sequence) stars live the longest, and why?  The shortest?

2. Why don’t stars live forever?

3. What makes an ordinary star become a Red Giant?

4. How do stars of low mass die?  Of high mass?

5. What is a nova?

6. What is a supernova?  How do the two types of supernovae differ from each other?

7. What makes the core of a massive star collapse?

8. Who was able to observe the supernova that lead to the Crab nebula?

9. What would happen to someone falling into a black hole?

10. Type I Supernovae, which occur when the material dumped onto a _______________ from its companion star makes this star exceed it Chandrasekhar limit, are believed to leave no core behind.

Homework #16

Space Travel
 

1. Choose five space probes and match them with planets, our Sun, our Moon, asteroids, and comets (some have visited several of these): Galileo, Giotto, Huygens, Luna, Mariner, Pioneer 1&2, SoHO, Ulysses, Venera, Viking, Voyager 1&2.
2. Space probes are not sent to other stars (besides our Sun) because ...
3. In what kind of orbits would one find spy satellites, surveying satellites, the DoD's GPS satellites, and communication satellites?  And why?
4. What were the political goals of Apollo?  Its scientific goals?  What are the political goals of the ISS?  Its scientific goals?
5. Name three famous astronauts and their claim to fame.  Three famous cosmonauts.
6. How does spaceflight affect the human body?
7. Why is ESA's launch pad in French-Guyana and NASA's in Florida and why do they launch Eastward?  (Hint: look at a globe and rotate that globe.)  Find out where Russia's, India's, China's and Japan's launch pads are.
8. What was the Sputnik shock and how did it affect American society?

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