Lecture meets M 4:10 PM - 6:55 PM in Science 101
Office: Science 356
Office Hours: M 1-3 PM, T9-10 AM and 2-4 PM, Th 9-10 AM, or by appointment
Email: jfielderATsfsuDOTedu (Replace AT and DOT with appropriate symbols and include "Astro 115-06" in subject line)
Syllabus: PDF
Voting Card: PDF
Physics and Astronomy Department's Plaigiarism Policy and Withdrawal Policy (PDF files)
SFSU Observatory Information
Astronomy 115 and 116 Help Sessions (open to all Astronomy students)
FINAL EXAM IS MONDAY 12/19, 4:10-6:55PM in Sci 201
No Reading, study for final exam!
12/12/11:
We started off class by doing course evaluations, then discussed material on cosmology from chapters 16 and 17. I went over Obler's Paradox, which explains why the universe had to have a beginning. I also talked about how the basic properties of isotropy and homogeneity lead to the cosmological principle. We saw how the cosmological principle combined with Hubble's Law means that the universe must be expanding. I explained the idea behind the Big Bang, and how it predicts the existence of the Cosmic Microwave Background (CMB) and the abundance of light elements. We also went over the fate of the universe, and how the density of the universe controls the expansion. After the break we went over life in the universe, the search for extrasolar planets, and the SETI project. I explained the details of the Arecibo message, and ended with Carl Sagan's "Pale Blue Dot" speech in response to this photo of Earth.
Reading for 12/12: Chapters 16 and 17, skim Chapter 18 (Focus on: Big Bang, Fate of the Universe, and the Habitable Zone)
12/5/11:
Today we focused our attention on galaxies: the giant collections of millions or billions of stars that populate our universe. First we looked at the galaxy our solar system resides in, the Milky Way. We looked at the size, shape, and mass of our galaxy, and did the Milky Way Scales lecture tutorial. I also talked about how we know where star formation is happening in the galaxy, and how astronomers learned of the existence of dark matter by measuring the mass of the galaxy. After the break we learned how to sort galaxies into different types using the Hubble classification system, and did the Classifying Galaxies lecture tutorial. I talked about how astronomers use Cepheid Variables, main sequence fitting techniques, and Type Ia supernovae as standard candles to measure distances to other galaxies. Next, we looked at how most galaxies have a redshifted spectrum, and saw how Hubble's Law describes the relationship between a galaxy's redshift and its distance. At the end of class, we learned that the expansion of the universe is the underlying source for all these redshifts, and I did a short demonstration showing why we would see the characteristics of Hubble's Law in an expanding universe.
Reading for 12/5: Chapter 14 and Sections 15.1-15.3, focus on Figs. 14-1, 14.16, 15.7, 15.10, and Hubble's Law section
11/28/11:
Today I did a quick recap of main sequence lifetimes, and we spent the first half of class talking about what happens to stars as they die. We looked at three different categories: very low-mass stars that stay on the main sequence, medium-mass stars like the sun that swell into giants and end as a planetary nebula and white dwarf, and high-mass stars that turn into supergiants then explode in a supernova and leave behind either neutron stars or black holes. I talked about how to tell planetary nebulae and supernova remnants apart, and described the properties of white dwarfs. After the break, we looked at neutron stars and black holes. I went over the properties of neutron stars, and described how astronomers know that neutron stars exist because we can see pulsars (a particular type of spinning neutron star with a very stron magnetic field). I talked about what conditions need to happen for a black hole to form from a very massive star, and how black holes have an escape velocity that is greater than the speed of light inside the event horizon. We learned about the strange phenomena that wouldhappen if you got too close to a black hole, and I answered several questions that the class still had about black holes. At the end of class we did a participation activity about stellar evolution. If you were struggling with that question, I recommend doing the Stellar Evolution lecture tutorial on page 121-122.
No class next week (11/21), enjoy the break!
Reading for 11/28: Sections 12.3, 12.4, 13.1, 13.2, and 13.3; focus on Fig.s 12.22, 13.3, 13.4, and 13.9
11/14/11:
We started Chapter 12 today, which concerns the formation of stars. We learned about the properties of the interstellar medium (or ISM), and how astronomers typically detect it. We learned about the differences between emission and reflection nebulae, and why astronomers expect stars to form out of cold, dense molecular clouds. We watched a simulation of stars forming out of a 50-solar-mass nebula, and talked about the timescales involved in stellar formation. Next, we learned how stars use a balance between gravity and thermal pressure from fusion to stay stable and do hyrdogen fusion for millions or billions of years. We talked about the different main sequence lifetimes of stars of different masses, and did the Star Formation and Lifetimes lecture tutorial before the break. After our break, we took Midterm #3. I will be posting scores for the midterm by the end of the week. There's no class next week (11/21), enjoy the holiday!
Reading for 11/14: Sections 12.1 and 12.2, focus on Fig.s 12.2 and 12.12
11/7/11:
We started off class this week by going over how parallax can be used to measure distances to stars, and did some examples of how to calculate distance from parallax. We did the lecture tutorial on The Parsec, and then answered some voting questions. Next, I talked about how luminosity and magnitudes are used to gauge the brightness of stars, and how the mangitude scale works. We looked at the wide range of luminosities and sizes that stars can have, and learned that luminosity is determined by the size and temperature of a star. We did the Luminosity, Temperature, and Size lecture tutorial after the break, and then learned how astronomers organize this information by plotting stars on the H-R diagram. I went over the structure of the H-R diagram (axes, regions where we find stars, etc.) and then we did the H-R Diagram lecture tutorial. I talked about how stars on the main sequence in the H-R diagram are all connected by the fact that they're fusing hydrogen into helium, and how critical a role the mass of the star plays in what its properties will be. We did some practice problems with magnitude and distances, and turned in the last practice problem for participation at the end of class.
Reading for 11/07: Chapter 11, focus on Table 11.1, Fig. 11.3, and pages 320-321
10/31/11:
Today we finished up material from Chapter 6 by going over the four steps in planet formation and doing the Temperature and Formation of Our Solar System lecture tutorial, then moved on to Chapter 10. We first looked at the basic properties of the Sun, then studied the three layers of the Sun's atmosphere. We also looked at different types of solar activity (similar to weather) and I showed several videos from the Solar and Heliospheric Observatory's movie gallery. Next, we focused on the Sun's interior and learned how the Sun uses the proton-proton chain to fuse hydrogen into helium and produce energy. Towards the end of class I showed this animation of the p-p chain and this demo of fusion in the Sun. We did a short participation activity at the end of class, making predictions about how the fusion demo would change under various circumstances.
Reading for 10/31: Chapter 10, focus on Fig.s 10.3, 10.6, 10.14, and 10.19
10/24/11:
Today we started looking at the general characteristics of the Solar System. We first described the difference between a planet and a dwarf planet, and learned why Pluto is now considered a dwarf planet along with Eris, Sedna, and Ceres. We looked at the differences between terrestrial planets and jovian planets, and learned some interesting facts about each of the eight planets in our solar system in particular. I went on to describe Nebular Theory, which is how astronomers think most planetary systems form around stars. I showed some evidence for why the planets in our solar system all have similar orbit and spin directions, and why their orbital planes are so well aligned. Finally, we explained the differences between terrestrial and jovian planets by noting that the solar nebula would have had different temperatures at different locations. We'll finish up with Chapter 6 next week. After the break, we took the second midterm exam.
Reading for 10/24: Sections 6.2, 6.3, and 6.4 (focus on Table 6.3, and Fig.s 6.17 and 6.24)
10/17/11:
I began class with a quick recap of the visible portion of the EM spectrum, and how the different visible colors break down by energy and wavelength. Next, we learned how to read an object's temperature and total energy output from its thermal radiation spectrum. After that, I talked about how the Doppler Effect allows us to measure the speed of an object as it moves either towards or away from us. We did the Doppler Effect lecture tutorial, and did some voting questions after the break. Finally, we covered the material from sectio 5.3 on telescopes. We learned why research-grade telescopes are so huge, and why they are mostly reflectors rather than refractors. I went over the two main functions of a telescope, and considerations that astronomers and federal funding agencies must take into account when deciding whether to build a particular telescope in space. We did the Telescopes and Earth's Atmosphere lecture tutorial, and finished up class with a participation question.
Reading for 10/17: Section 5.3 (focus on "Two Key Properties" and fig. 5.25) and 6.1 (Focus on Table 6.1)
10/10/11:
Today we started covering material from Chapter 5, which looks at how we can learn about objects in space from the kinds of light they produce. First we looked at the basic properties of light such as wavelength, frequency, energy, and speed. We learned how these properties are related, and looked at the different sections of the EM spectrum. We did the EM Spectrum of Light lecture tutorial, and then did a few voting questions. Next, we looked at the basic properties of matter, and how we can model the atom as a nucleus and electrons in different energy levels. After the break we learned more about how atoms can emit or absorb light (and used the Hydrogen Atom Simulator to see this in action), and learned about the three basic types of spectra. We did the Light and Atoms lecture tutorial, and finished up class with a participation activity and more voting questions.
Reading for 10/10: Section 4.2, pg. 98-99, and Sections 5.1-5.2
10/03/11:
We started class today with a quick review of where we ended last week, then talked about the contributions of Tycho Brahe to the subject of planetary motion. Next, we learned how Johannes Kepler was able to figure out his three laws of planetary motion, and went over each of those three laws in detail. I showed how these laws work with this Planetary Orbits demo, and we did the Kepler's Third Law lecture tutorial. I also mentioned that there's an optional lecture tutorial on Kepler's Second Law on pg. 21 that students might be interested in doing for practice. After the break we learned about Newton's Laws of gravity and motion, and learned how gravity keeps planets in their orbits using a short in-class participation activity. We did the Newton's Laws and Gravity lecture tutorial, and ended class with a few voting questions.
Reading for 10/3: Review Kepler's Laws (pg. 67-68), and Section 4.1
09/26/11:
In the first half of class we finished up Chapter 2 and started Chapter 3. First, we looked at the motion of the planets compared to the rest of the stars (described as "prograde" when moving forwards and "retrograde" when moving backwards). We also learned how the ancient Greek philosophers described these motions using Ptolemy's model, which has the Sun and other planets moving around the Earth. To get an idea of what this model looks like, I showed this Ptolemaic System Simulator. Next, we did the Observing Retrograde Motion lecture tutorial, and learned about Copernicus's model of the solar system which explains the motions of the planets by having them and the Earth orbit the Sun. We used this Planetary Configurations Simulator to see how prograde and retrograde motion work in a Sun-centered model. Finally, we learned about the observations Galileo made with a telescope that convinced him that the universe is best described by a Sun-centered solar system. We took the first midterm exam after the break, and will continue with planetary motions next week.
Reading for 9/26: Chapter 3, and STUDY FOR MIDTERM #1
09/19/11:
Today I started class off with a review of the zodiac and seasonal stars, and we did a few voting questions related to last week's lecture tutorials. Next, we talked about why Earth has seasons. I began with a description of the seasonal changes we observe from Earth, including how the position of the Sun changes at sunrise, sunset, and noon throughout the year. We talked about the solstices and equinoxes, and I used the Motions of the Sun Simulator to show these in action. Next, we brainstormed about why the Earth might be experiencing seasons, and came to the realization that it must be due to the tilt of the Earth's axis. This 23.5-degree tilt causes rays of sunlight to hit the ground at a different angle at different times of the year, which we saw in the Seasons and Ecliptic Simulator. We did the Seasons lecture tutorial, and answered some voting questions after the break. We also learned about the phases of the Moon, and how the moon's appearance, rise time, and set time are connected to the Moon's location in its orbit. I used the Lunar Phase Simulator to show how this works, and we did the Cause of the Moon Phases lecture tutorial. At the end of class I quickly talked about lunar and solar eclipses, and we did a short participation activity right before the end of class. Next week we'll have regular lecture at the beginning of class, and then take the first midterm after the break (see the review sheet posted above for more information about the exam).
Reading for 9/19: Finish Chapter 2
09/12/11:
This week I began class with a reminder of how we determine an object's location in the sky, and discussed how angles are used to measure distances on the sky. Next, we looked at how Earth's spin (which takes 24 hours to complete once) controls the apparent rising and setting of the Sun, Moon, stars, and planets. We did the Motion lecture tutorial and answered a few voting questions before the break. Then, we learned how an observer's latitude on Earth changes what is visible in the night sky. We saw that an observer's latitude is the same as the height of their celestial pole above the horizon. We also learned that certain constellations are "blocked" by the Sun at a particular time in the year, and that these constellations of the zodiac are only visible at certain times depending on Earth's location in its orbit. We looked at how the zodiac has changed due to astronomers redefining the constellation boundaries and the precession of Earth's axis. We finished up class with the Seasonal Stars lecture tutorial, and will do some more voting questions at the beginning of class next week.
No class next week (9/5), Labor Day holiday
Reading for 9/12: Chapter 1 and Sections 2.1-2.2
08/29/11:
Welcome to Astronomy! I spent a large chunk of time at the beginning of class going over the syllabus, which you can find posted in the above section. Please make sure you carefully read and understand the syllabus, as it contains important information about how your grade will be determined in this course. We talked about the nature of science and how the scientific method gives us a rigorous framework for advancing our knowledge of the universe, and looked at some examples of the advancement of science through astronomy. We also did a brief review of scientific notation and went over some units of length we'll be using frequently throughout the semester (you can review units and scientific notation in Appendix C of your textbook). During the second half of class, I talked about how astronomers use constellations, asterisms, and the celestial sphere model to describe locations and positions on the night sky. We used this demo of the Celestial Sphere to visualize why stars rise and set. Near the end of class we did the Position lecture tutorial, and finished up with some voting questions.
