y SDSU Astr 310 "Astrobiology"

ASTR 310 IMPORTANT CLASS NEWS AND INFORMATION


Astrobiology Magazine is an superb on-line astrobiology news magazine. These "news feed" links are the latest from Astrobiology Magazine:


A very nice "zoom" on the Universe: "Powers of Ten" from the "Molecular Expressions" web site (requires java).



May 7:
- The last set of lecture notes - a "big picture" summary: The Big Picture
- Take a few mintues and take the Planet Quest "Alien Safari" It is a nice review of some of what we've learned in this course.
- From last year's class: PRELIMINARY Final Exam Study Guide. This is not the final version for this semester, but it will be similar, so you can get a head start if you wish.
- Repeat Lecture notes: What is astrobiology?





May 2:
Lecture notes on:
+ SETI
+ The Rare Earth Hypothesis & Some Critical Thinking Notes
- The final set of excercises and problems for you to do on your own: Teach Yourself #4 and 5.

Apr 30:
- Lecture notes on: The Drake Equation
- Two news articles from The Planetary Society:
+ "Chemistry and Physics Suggest a Soup Under Enceladus' South Pole" and
+ More on the Gliese 581c planet "Most Earth-Like Planet Discovered Orbiting Nearby Star"

Apr 28:
- Lecture Notes on: Extrasolar planets
- Gliese 581 is an M star with a 5-earth-mass planet in its "habitable zone": ESO Press Release: Astronomers Find First Earth-like Planet in Habitable Zone. An shorter summary from Astrobiology News: Astronomers Find Habitable Earth-Like Planet

Apr 24:
- Lecture notes on: Mars, Part 2
- MER Results Evidence of Water Found on Mars (article from Astrobiology Magazine).
- Opportunity Finds Beachfront Property on Mars The rocks ... "were not just altered and modified by water; they were actually formed in water, perhaps a shallow salty sea, ..." (From Astrobiology Magazine).
- Martian Salty Sea "...some rocks on Mars probably formed as deposits at the bottom of a body of gently flowing saltwater." (From Astrobiology Magazine).

Apr 22:
- Lecture notes on: Mars, Part 1
- Recent news (2008 Mar 23): Cassini Spacecraft Finds Ocean May Exist Beneath Titan's Crust
- Recent news (2007 Mar 13): Discovery of sea on Titan, Viewed by Cassini's Radar "This image of Saturn's largest moon, Titan, obtained by Cassini's radar instrument during a near-polar flyby on Feb. 22, 2007, features dunes and lakes, one of which is larger than any lake on Earth and could be legitimately called a sea."
See also: Cassini Spacecraft Images Seas on Saturn's Moon Titan
- Recent news about Enceladus (2007 Mar 14 Astrobiology Magazine): A Hot Start on Enceladus: "Deep inside Enceladus, our model indicates we've got an organic brew, a heat source and liquid water, all key ingredients for life," said Dr. Dennis Matson, Cassini project scientist at NASA's Jet Propulsion Laboratory, Pasadena, Calif. "And while no one is claiming that we have found life by any means, we probably have evidence for a place that might be hospitable to life."

Apr 13:
- For more on the status of Pluto as a non-planet, see the interview with Michael Brown from Astrobiology Magazine.
- NASA's Cassini Discovers Potential Liquid Water on Enceladus

Apr 11:
- Lecture notes on Europa and Titan.
- Jupiter's moon Europa should be NASA's next target from Astrobiology Magazine (2007 Mar 02).
- The Exam #2 average = 39.3/50; min-to-max range= 20-49.
Approximate score-to-grade conversion for Exam #2:
A = 44-50
B = 37-43
C = 31-36
D = 25-30

Apr 9:
Exam #2 Studyguide.
- Lecture notes on: Venus
- This past July was the 38th anniversary of the historic Apollo 11 Moon landing. Read more about it at NASA's Apollo 11 site. See also the very interesting related site: What Have We Done For You Lately? NASA Connections to Everyday Life.


Apr 7:
- Exam #2: Friday Apr 11. The exam will consist of 50 multiple choice questions. Please use a clean, unfolded ParSCORE Enrollment scantron, and fill out the Red ID, etc. before the exam. You will lose 1 point for every error on your scantron form. Please fill out the information carefully. This is a closed book exam: No calculators, PDAs, cell phones, mp3, etc., allowed (slide rules are ok).
- Preliminary hints for Exam #2.

Mar 28 - Apr 4 (Spring Break):
- Lecture notes on: Chicxulub & the K-T extinction.
- From NASA's NEO Program website: "Near-Earth Object Testimony before the U.S. House of Representatives Subcommittee on Space and Aeronautics." In particular, see the link to Apophis' 2029 and 2036 threat. What is "Apophis"? It is a NEO that ``...in 2004, Apophis was briefly estimated to have a 2.7% chance of impacting the Earth in 2029...''
- A student found a very nice website showing photos & videos of meteors: Meteorite Action!
- Another website showing a recent meteor burning up in the sky on Jan 4th 2007: Denver Colorado Meteor Shower. Of course this has nothing to do with aliens, but that won't stop some wild ideas by those who don't know much about meteors.
- An "astrobiology A-Z" list: This list of ideas and topics in astrobiology can serve as a good review: by the time of the final exam, you should know the definitions and relevance of all the items on the list.
- The answer to Written Homework #3, part 3.

Mar 25:
Several students have asked for help with the 3rd part of HW #3, about the genetic code, so here are additional tips. First, please see the revised hints below.
1) use the table in the Course Reader to do the problem. The table in the textbook on page 175 is non-standard(!!): it lists the DNA codons, not the RNA codons. (Sites like wikipedia also have the correct RNA genetic code.)
2) the questions wants you to list the before and after codons on the DNA, not the RNA. Remember that the way DNA works is that one half of the DNA strand in the gene is copied to form mRNA, then the mRNA makes the protein. So be sure to use the complementary base pairs, not the RNA codon bases.

Mar 24:
- Lecture notes on: Jovian Planets, Meteors & Comets
- HINT, Clarification, and Extra Credit for the homework question about the genetic code.
Clarification: When I said there were 8 possible combinations, that is not correct. What I meant to say is that there are 8 different codons involved and you should list them all, not just one solution. There are two codons involved before the change and six codons after.
Hint: Make a table with 4 columns; each column will have a list of codons.
. a) the first column is for the RNA codons before the change
. b) the first column is for the DNA after the change
. c) the second column is for the RNA codons after the change
. d) the third column is for the DNA codons after the change
. The second and third columns contain your answer.
REMEMBER THAT THE DNA BASES ARE *COMPLIMENTARY* TO THE RNA BASES!
Extra credit: Which of these possible changes (mutations) are most likely to occur? Why?
- Reminder: If you find a mistake in the textbook, I will award you an extra credit point. Like most books, there is misteaks. (sic)
- Reminder: Somewhat unsure about what plagiarism is? Read the bottom of the class homework web page.

Mar 22:
Organics Found on Alien World "Hubble has made the first detection of an organic molecule in an extrasolar planet. The breakthrough is an important step toward identifying signs of life on a planet outside our Solar System." - Astrobiology Magazine.
Final reminder: please don't forget the last part of Homework #3. As always, explain your answer in full.

Mar 20:
- Lecture notes on The Earth's atmosphere
- Lecture notes on: Radioactivity
- Again, please note the final question of the 3rd Written Homework set is now posted. Homework #3 is due next Friday. Homework #2 will be returned on Monday Mar 24.
- Some recent news about the organic material in meteorites that may have been the source of the building blocks of life: Meteorites a Rich Source for Primordial Soup from Astrobiology Magazine.

Mar 18:
- I will not be able to make office hours on Wed March 19th at 2pm. If you would like to see me, we can schedule a meeting at some other time this week.
- Lecture notes on: The Earth's interior.

Mar 17:
Please note the final question of the 3rd Written Homework set is now on the web page. Apologies for its omission.

Mar 12:
- Lecture Notes on: Comments on the Origin of Life
- Historical perspective on the discovery of the Archaea: "30 Rings on the Tree of Life" from Astrobiology Magazine.

- Lecture Notes on: The Tree of Life
- As mentioned in class, please do not fall to behind in the reading. We are covering these biochemistry and biology topics very quickly. Please read the textbook and Class Reader material first, then ask questions in class when we cover the same topics.
Extra credit details: (1) don't spend too much time on these! ; (2) it is worth 1 point added to your exam score ; (3) deadline: March 17.

Mar 4:
- Alas, we failed to get the extra credit bonus for having perfectly filled out scantrons. There were a whopping FIVE bad scantrons, including one that couldn't even be read because the edges were so bent and crumpled. Maybe next time we can do better and get the extra credit.
- Exam #1 mean score = 38.0 / 50.0; approximate score-to-grade conversion:
... A = 44-50
... B = 38-43
... C = 30-37
... D = 25-29. The grades were based on a curve, but the curve was quite mild and very similar to curves from previous semesters.
- Who was this guy Bruno that's quoted on the class web page? Read the Giordano Bruno biography from the Galileo Project.

March 3:
- Lecture Notes on: The Molecules of Life
- Lecture Notes on: Quick Intro to Chemistry

---> Feb 29:
+ Warning: Plagiarism includes copying out of the textbook! Just because it is the textbook we are using does not mean you can steal from the book. Please don'r commit plagiarism and fail the course by copying out of the glossary!
+ Official Study guide #1 for the first midterm exam.

Feb 27:
EXAM #1 RESCHEDULED FOR MONDAY MARCH 3.
 Homework #2 is still due on Monday.
For the problems in Homework #2 where you have to show all work, please briefly write out in words what you are doing. Don't just write down a formula. A formula is simply a shorthand mathematical way of saying the concept, but by itself it is meaningless. For example, if I say "E = h f", that doesn't mean anything. What is "E"? Is this eccentricity, electricity, energy, excitation, ... ? Is "h" the height? Is "f" the force, or the friction, or what? But if I write, "The energy of a photon equals the Planck constant times the frequency of the light", then I've said something. I would know that if I double the frequency, I double the energy. Another example: "56,000,000/300,000 = 186" means nothing. But if you say, "The distance divided by the speed tells me the time it takes to get somewhere. In this case, radio waves travel at the speed of light, c, which equals 300,000 km per second". Then you are showing that you really understand the material and that you how to do the problem. And as a bonus, you are *much* more likely to get the correct answer.

Feb 25:
- POSTPONED TO MONDAY: Reminder: Exam #1 on Friday, but...
- We are about 1 lecture shy of a good stopping point. Rather than split the topic, I prefer we finish the discussion of the creation of the elements and the formation of stars and planets without rushing. So I propose we move the exam to Monday. This also gives us time to discuss items in the Course Reader. What do you think? We'll decide in class on Wednesday.
 - Lecture notes on: Star & Planet Formation; The Solar System

Feb 24:
*DRAFT* Beta Version 0.9 Hints for the first midterm exam. This is not the final version, but just a guide to get you started.

Feb 22:
- Lecture Notes on Stellar Evolution
- Exam #1: Fri Feb 29. 50 multiple choice questions; you need a ParSCORE Student Enrollment scantron form (the big pink one), #2 pencils, eraser. No calculators, PDAs, cell phones, ipods, etc., allowed. (Slide rules are allowed.)
- Be sure to fill out your ParSCORE form correctly! If you have mistakes, you will lose points on your exam (1 point per error). Common errors include:
. + putting an extra zero in front of your Red ID
. + putting a blank in front of your Red ID (leave the last column blank)
. + filling in wrong digits on your Red ID.
. + filling in two answers bubbles because of sloppiness
. + not erasing an answer fully
Fill out your scantron form BEFORE the exam.

Feb 20
- Lecture Notes on Critical Thinking
- "More than ever, we'll need to constantly keep in mind that memory, like liberty, is a fragile thing." - E. Loftus, as quoted from New Scientist Magazine's brief (1-paragraph) story Elizabeth Loftus forecasts the future

Feb 18:
- Special Offer #3 (for extra credit) is now closed.
- For more on the profound discoveries of Dr. Loftus see the ``Related Sites: Critical Thinking, Pseudoscience, Aliens, UFOs, etc.'' section of our class wwweb pages for links to (i) the Scientific American article (that unfortunately was poorly reproduced in the Class Reader); (ii) a really fascinating, and perhaps even anger-generating, article titled, "Who Abused Jane Doe? The Hazards of the Single Case History" printed in the Skeptical Inquirer. You can also visit Dr. Loftus' wwwebsite at: http://www.seweb.uci.edu/faculty/loftus/

Feb 17:
- Special Offer #2 is now closed.
- Special Offer #3 (for extra credit) is still open.
- Lecture notes on: AGN
- "Don't think of empty space as nothing;
Think of it as something with nothing in it."
For example, consider time. You can certainly measure it. And you have an intuition of what it is. But try to define it. One thing is for sure: it is something; it is not nothing. Well, that's about as good an explanation that I can offer. The notion of space stretching is not a trivial concept, so don't fret if it doesn't make sense immediately. For some, it will never make sense, and for those people I offer the following thought. Here is a very rough adaptation of a relevant section from Lao Tsu's Tao Te Ching, Book 11 (this not at an exact translation, but I think it gets the point across):
"Consider the teacup:
It is not the sides of the cup that give its usefulness,
But rather the empty space they create."
Feb 15:
- Teach Yourself (#3): This problem will help you understand the relation between Hubble's law and the age of the Universe:
Suppose the Hubble constant H0 = 750 km/s per Mpc. How old would the Universe be? Do you think this is ok? (Here are hints for the problem.)
- Final call for extra credit Special Offer #2.
- Special Offer #3 - Extra Credit: For those of you who are theater majors, or actors, or wannabe actors, or who just like like to talk, I have a job for you. I need two students to act out a very short dialog between two friends. This 1-2 minute dialog will be in presented in class. I will provide the "script" ahead of time and all you have to do is slowly read it. The first two students who respond to this Special Offer will be asked to perform the dialog and will earn extra credit worth 1 exam point.
No acting skill is necessary. (I used to have TA's help me with this, and boy, they definitely could NOT act!) Send email to the class email account if you are interested and I will send you the dialog.

Feb 11:
- Special Offer #2 is still open - I have a few more books from the publishers
- Teach Yourself (#2): Try working out this problem - it will help you understand the Doppler effect:
The observed wavelength of the H-alpha line in a star is 653.450 nm. The true wavelength of the H-alpha line (measured at rest in the lab) is 656.255 nm. What is the radial velocity of the star? (Here are hints on how to do the Teach Yourself problems.)
- Change of plans: Dr. Welsh will have Office Hours as usual this week. Earl Towson will still be giving a guest lecture on Wednesday though.

Feb 8:
- Lecture notes on: Cosmology & the big bang.
- Reminder: Written homework #1 due on Monday. Pages must be stapled together.
- When dropping off your homework please put it in the correct folder. The folders are labeled by the first letter in the student's last name.

Feb 3:
- Special Offer #2 is still open.
Lecture notes on:
- Electromagnetic Radiation.
- Notes on atomic structure & spectroscopy. Remember, all class notes are copyrighted.
- Dr. Welsh will not have office hours during the week of Feb 11-15.
- We will have a guest lecturer, Earl Towson, a JPL Ambasssador, on Wed Feb 13th.

Jan 30:
- If you find an error in the textbook, reader, notes, lectures, or web pages, please notify me and you may earn extra credit. In general, I don't award extra credit for spelling errors or typos. But major errors, like an incorrect date for an exam on the syllabus, would definitely earn you extra credit.

Jan 28:
Special Offer #2: Need help with some astronomy concepts? Confused by solar system vs. galaxy? Is a light year a distance or a time? "Parallax" vs. "parsec"? Hubble trouble? The first two replies to this "special offer" will be loaned an introductory astronomy 101 textbook for the semester. (This is *not* the astrobio course textbook!) Send e-mail with your name and the words "Textbook" to the class e-mail account: astr310@rohan.sdsu.edu I only have two spare textbooks - sorry I can't loan out more.

Jan 26:
- Special Offer #1 is closed. Thanks to all students who asked for a copy - sorry I don't have more to lend out. I used to have more, but over the last two semesters some students didn't return the ones I loaned out, so I only had one spare this semester.
- Lecture notes: Parallax, Galaxies, & Large Scale Structure of the Universe.
- Teach Yourself (#1): Try working out this problem - it will help you understand the size and scale of the solar system: What is the minimum amount of time it would take to send a command to a robotic spacecraft on the surface of Europa? (Here are hints on how to do the Teach Yourself problems.)

Jan 25:
- For those who may need help or a review of some mathematics, please read Appendix C of the textbook.
- Special Offer #1: I have 1 spare Course Reader that I can loan out for the semester. These were donated by previous Astr 310 students. The first student to send e-mail to our class e-mail account can borrow a Reader. Please put the words "Astrobio Reader" in the subject line of your message.
- For fun, you can observe a total lunar eclipse on Wed Feb 20th. Totality starts at 7:01pm and ends at 7:51 pm.

Jan 23 :
- Reminder: This course can only count towards satisfying your GE requirements if you will have completed 60 or more units by the end of this semester.
- Lecture notes: You should be able to read the PDF files with almost any OS platform (linux/unix, Microsoft Windows,Apple/Mac, etc.). Here are a set of notes on the metric SI system and reference temperatures, lengths, and velocities.
- Lecture notes: What is astrobiology? (.pdf format)
- Lecture notes: Stars, Vastness of Space, Clusters and Nebulae
** All class notes are copyrighted. **
The on-line class notes are available to augment classroom learning - their sole purpose is to prevent frantic writing of notes and allow students to spend time listening, thinking and comprehending the lecture. They are not intended to be, nor do they function as, a substitute for attending the lectures. For maximum value, you should: (i) read the homework assignments first (especially the textbook reading assignments which cover material well before we discuss the topic in class); (ii) bring the notes to the lecture so you can add comments, sketches of figures, and material not in the notes. Any other use of the on-line lecture notes is inappropriate at best and detrimental at worst.
The on-line notes will not be available all semester - they are posted several days before the lecture, then removed a few days after the lecture - no exceptions. This is for the students' benefit. So please keep up with the class.

Reminder: The lecture notes, along with all other class material, are copyrighted.




Dr. Welsh's office is on the 2nd floor of the Physics Building, Room 235, just across the street from the front entrance of the GMCS building.


If ever an emergency alarm goes off, please grab your stuff and calmly evacuate the building. The meeting point is at the grass-covered area just outside the Physics building (next to the bicycle symbol on the map below).

Some fairly recent interesting news/discoveries in astrobiology.



Please don't confuse the terms "hypothesis" and "theory". As used in science, a theory is a very strong term and only a handful of ideas in all of science qualify as a theory. A hypothesis is an educated guess or explanation, and implies insufficient evidence or comprehension for a more concrete understanding. A theory is a well-tested, well-established hypothesis, able to make far-ranging predictions and connections with other theories, and usually with an elegant mathematical or physical mechanism for its operation. A theory is much stronger than a hypothesis. It has been rigorously tested by many independent people. When speaking in technical terms, don't use the word "theory" when you simply mean speculation or conjecture or idea or educated guess (all of which are synonymous with hypothesis). In science-speak, we don't come up with theories, we come up with hypotheses. But that's not the way the word "theory" is used in common conversation. Keep this in mind so you don't get confused when you hear someone say, "It's only a theory." That theory may encompass the sum total of all of human experience and knowledge! A better way to think of the word theory is to equate it with the word "law". That is closer to the meaning that scientists intend when they call something a theory.



Last major update on 2008 Jan 19. Updates occur frequently.

This page has been accessed times since 2004 Jan 10