ASTR 101(F) LEC Stars: From Suns to Black Holes

Looking at the Sun and the sky at night have you ever wondered why they are shining and what they are made of? Do they evolve and if so how do they change? The last decade has brought exciting new astronomical discoveries. For the first time a gravitational wave signal produced by merging of two black holes has been detected. The gravitational wave antennas detected the merger of two neutron stars which also caused flashes throughout the whole electromagnetic spectrum from radio waves to very energetic gamma rays. We now know that most of the heavy elements that exist in nature were formed during mergers of neutron stars. Large telescopes, new detectors, and new observational techniques have also made possible the discovery of thousands of exoplanets. The recently launched James Webb telescope is discovering galaxies that were formed soon after the Big Bang and is observing atmospheres of exoplanets to search for possible signs of life. Here on Earth, there is soon to be total solar eclipse that will be visible in the Southern and North-Eastern parts of the US on April 8, 2024. In this course, to help you appreciate and better understand the continuous stream of astronomical discoveries, we will discuss the basic methods and instruments used in astronomical observations, but also discuss what is happening at the centers of stars and how they evolve and why some stars explode and form neutron stars and black holes. [ more ]

ASTR 102 LEC Our Solar System and Others

Last offered Spring 2022

What makes Earth different from all the other planets? What have NASA's Curiosity and Perseverance on Mars (with their alumni/ae participation!) found about that planet's past running water and suitability for life? How has knowledge about Pluto and Arrokoth beyond it been transformed by NASA's flybys and the associated ground-based studies with which Williams College faculty and students participated? Will asteroids or comets collide with the Earth again? What is a solar eclipse like and how do we prepare for the April 8, 2024, totality? What do we learn from the rare transits of Mercury and of Venus that Williams faculty and students have studied? What may the new James Webb Space Telescope reveal about exoplanets and their atmospheres? Astronomy 102, a non-major, general introduction to the part of contemporary astronomy that comprises the study of the solar system (and the systems of planets around other stars), will provide answers to these questions and more. We will cover the historical development of humanity's understanding of the solar system, examining contributions by Aristotle, Ptolemy, Copernicus, Galileo, Kepler, Newton, Einstein, and others. We will discuss the discovery of over 4000 exoplanets around stars other than the Sun. The course gives special attention to exciting discoveries of the past few years by space probes and by the Hubble Space Telescope and the Kepler/K2/TESS missions, as well as plans and hopes for NASA's James Webb Space Telescope (which launched in December 2021). We regularly discuss the latest news briefs and developments in astronomy and relate them to the topics covered in the course. This course is independent of, and on the same level as Astronomy 101 (stars and stellar evolution) and 104 (galaxies and cosmology), and students who have taken those courses are welcome. [ more ]

Taught by: Jay Pasachoff

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ASTR 104(S) LEC The Milky Way Galaxy and the Universe Beyond

How was the Universe created, and how has it evolved to its presently observed structure? This course will start at the Big Bang, the beginning of everything, and move forward from there. About five centuries ago Galileo Galilei used his own primitive telescope to make many astronomical discoveries: observing the moons of the Jupiter, craters on the Moon, and Sun spots to name a few. Galileo also noticed that stars are not spread on the celestial sphere at random but form a disk like structure, which we now call the Milky Way Galaxy -- our cosmic home. Almost a hundred years ago Edwin Hubble discovered that the Universe contains many galaxies and that they are moving away from each other. Hubble discovered that the Universe -- the largest physical object -- expands, so it had a beginning. In this course we will explore the tools and techniques that astronomers use to study stars and galaxies. From the discovery of the Milky Way to the expanding Universe, we will cover the key concepts and discoveries that have shaped our understanding of the cosmos. During recent decades astronomers have made exciting -- and unsettling -- new discoveries: it turns out that most of matter in the Universe does not emit light and most probably is composed of particles of unknown origin, and that the expansion of the Universe is now accelerating, pushed by a mysterious dark energy. At this point, astronomers have evidence to show that at early epochs the Universe was very dense and very hot. This early epoch is called the Big Bang. How the Big Bang happened is not known yet but there are several interesting hypotheses that our Universe could be one of many. This course will introduce important highlights in the observation and interpretation of remarkable astronomical phenomena and explore these many mysteries. [ more ]

ASTR 107 LEC Astrobiology

Last offered Fall 2021

Astrobiology is the study of the origin, evolution, and distribution of life in the universe. As such it is an inherently interdisciplinary field, incorporating all of the basic natural sciences: biology, chemistry, physics, astronomy, and the earth sciences, as well as aspects of philosophy, sociology, and engineering. Questions we will seek answers to in this class include: How, why, when, and where did life evolve on Earth, and what does that tell us about how it might evolve elsewhere? What are the chances that there is life on other planets and moons in our solar system, and why? Are there habitable planets elsewhere in the universe, and will we ever truly know if any of them contain life? We will approach these questions using a combination of lectures, activities, labs, homework assignments, and visits from some of the country's leading Astrobiology researchers. Examples of lab and homework activities include exploring our definition of life by making observations about living and non-living systems, examining evidence for ancient habitable environments in rocks, and modeling chemical fingerprinting tools used by Mars rovers. Assessment will be based on participation, quizzes, labs and homework assignments, and a final group project where students will present a mock NASA mission proposal. This course requires no previous experience in the sciences. This course is in the Sediments and Life group for the Geosciences major. [ more ]

ASTR 111(F) LEC Introduction to Astrophysics

The science of astronomy spans vast scales of space and time, from individual atoms to entire galaxies and from the universe's beginning to the future fate of our Sun. In this course, we will survey some of the main ideas in modern astrophysics, with an emphasis on the physics of stars and galaxies. ASTR 111 is the first course in the Astrophysics and Astronomy major sequences. It is also appropriate for students planning to major in one of the other sciences or mathematics and for others who would like a quantitative introduction that emphasizes the relationship of contemporary physics to astronomy. Topics include gravity and orbits, radiation laws and stellar spectra, physical characteristics of the Sun and other stars, star formation and evolution, black holes, galaxies, the expanding universe, and the Big Bang. Students will also use telescopes to observe stars, nebulae, planets, and galaxies and to make daytime observations of the Sun. [ more ]

ASTR 211(S) LEC Astronomical Observing and Data Analysis

How do astronomers make scientific measurements for objects that are light-years away from Earth? This course will introduce the basics of telescopes and observations and will give students hands-on training in the techniques astronomers use to obtain, process, and analyze scientific data. We will discuss observation planning, CCD detectors, signal statistics, image processing, and photometric and spectroscopic observations. We will begin by focusing on ground-based optical observations and will move on to non-optical observations, both electromagnetic (e.g., radio waves, X-rays) and non-electromagnetic (e.g., gravitational waves, neutrinos). Throughout the course, students will use computational techniques to work with real astronomical data, taken with our 24" telescope and from data archives. [ more ]

ASTR 217 LEC Planets and Moons

Last offered Spring 2020

This course examines the history and geology of the solar system. No two planets are exactly alike, and as we acquire more data and higher-resolution images, our sense of wonder grows. However, we can't hike around and hammer rocks on Venus or Titan, so we have to infer composition, form, texture and process from remotely-captured images and sparse chemical and spectral data. We will consider the origin of the solar system, the formation and evolution of planetary bodies, and the role of impacts, volcanism, tectonics and geomorphology in shaping them. We will summarize basic geological concepts of stratigraphy, structure and chronology and show how they can be applied off-world. We will review solar system exploration, and will include planetary data in lab exercises. This course is in the Solid Earth group for the Geosciences major. [ more ]

ASTR 240 SEM Great Astronomers and Their Original Publications

Last offered Fall 2022

In this course we will study some of the greatest figures in astronomy and consider their leadership in advancing progress in the field. We will consider their lives and works, especially as represented by original copies of their books and other publications. These great astronomers include: 16th century, Nicolaus Copernicus (heliocentric universe); Tycho Brahe (best pre-telescopic observations); 17th century, Galileo (discoveries with his first astronomical telescope, 1610; sunspots, 1613; Dialogo, 1632); Johannes Kepler (laws of planetary motion, 1609, 1619, Rudolphine Tables 1627); Johannes Hevelius and Elisabeth Hevelius (atlases of the Moon and of stars, 1647, and 1687); Isaac Newton (Principia Mathematica: laws of universal gravitation and of motion, 1687); 18th century, Edmond Halley (Miscellanea curiosa, eclipse maps, 1715, 1724); John Flamsteed and Margaret Flamsteed (Atlas Coelestis, 1729); and William Herschel and Caroline Herschel (1781, 1798). Also, from more recent times in which original works are often articles rather than books: 20th century, Albert Einstein (special relativity, 1905; general relativity, 1916); Marie Curie (radioactivity); Cecilia Payne-Gaposchkin (hydrogen dominating stars, 1929), Edwin Hubble (Hubble's law, 1929); George Ellery Hale (Mt. Wilson Observatory 100" telescope, 1917; Palomar Observatory 200" telescope, 1948), Vera Rubin (dark matter, 1970s); Jocelyn Bell Burnell (pulsar discovery, 1968); and 21st century: Wendy Freedman (Universe's expansion rate, 2000s). First editions will be available in Williams' Chapin Library of rare books, where we will meet in an adjacent classroom. We will also consider how such original materials are collected and preserved, and look at examples from the wider world of rarities, such as a leaf from the Gutenberg Bible (c. 1453) and a Shakespeare First Folio (1623, with a discussion of astronomical references in Shakespeare's plays). The course will be taught in collaboration between an astronomer and a rare-books librarian, with remote lectures by experts from around the world. [ more ]

ASTR 317 SEM Current topics in Planetary Geology

Last offered Spring 2021

We will look in detail at geological processes on rocky and icy bodies of the Solar System. Each week will have a specific theme, and students will read a series of scientific articles on that topic. The readings will form the basis for writing and discussion. Areas to be investigated may include ice ages on Mars, the origin of Earth's moon, tectonics on Venus, chaos terrain on Europa, geysers on Enceladus, cryovolcanism on Triton, methane lakes on Titan, the viability of mining in the Asteroid Belt, and the prospects for life on other worlds. This course is in the Solid Earth group for the Geosciences major. [ more ]

Taught by: TBA

Catalog details

ASTR 330 LEC The Nature of the Universe

Last offered Spring 2023

This course is a journey through space and time from the first fractions of a second after the Big Bang to the ultimate fate of the Universe billions of years into the future. Topics include the Big Bang and its remnant cosmic background radiation, cosmic inflation, conditions during the first three minutes, creation of the elements, stellar and galactic black holes, relativity, the detection of gravitational waves, galaxies and quasars, dark matter, and the formation of the large-scale structure of the Universe. We will explore current ideas about the fate of our Universe, including the acceleration of its expansion, and its implications for the end of time. Finally, we will consider the fantastic but serious theoretical proposal that ours is but one of countless universes existing within a multiverse. [ more ]

Taught by: TBA

Catalog details

ASTR 336 SEM Science, Pseudoscience, and the Two Cultures

Last offered Spring 2018

A famous dichotomy between the sciences and the humanities, and public understanding of them, was laid down by C. P. Snow and has been widely discussed, with ignorance of the second law of thermodynamics compared with ignorance of Shakespeare. In this seminar, we will consider several aspects of science and scientific culture, including how scientific thinking challenges the claims of pseudoscience. We will consider C. P. Snow and his critics as well as the ideas about the Copernican Revolution and other paradigms invented by Thomas Kuhn. We will discuss the recent "Science Wars" over the validity of scientific ideas. We will consider the fundamental originators of modern science, including Tycho, Kepler, Galileo, and Newton, viewing their original works in the Chapin Library of rare books and comparing their interests in science with what we now call pseudoscience, like alchemy. We will review the history and psychology of astrology and other pseudosciences. Building on the work of Martin Gardner in Fads and Fallacies in the Name of Science, and using such recent journals as The Skeptical Inquirer and The Scientific Review of Alternative Medicine, we consider from a scientific point of view what is now called complementary or alternative medicine, including both older versions such as chiropractic and newer nonscientific practices. We will discuss the current global-climate-change deniers and their effects on policy. We discuss vaccination policy. We consider such topics as GM (genetically modified) foods, the safety and regulation of dietary supplements, and the validity of government and other recommendations relevant to the roles of dietary salt, sugar, and fat in health. We consider the search for extraterrestrial intelligence (SETI) and reports of UFO's and aliens. We consider the possible effects that superstitious beliefs have on the general public's cooperation in vaccination programs and other consequences of superstition. We will discuss conspiracy theories such as those about the Kennedy assassination, in view of the 2017 release of many documents from the time and the recent book by Alexandra Zapruder, the granddaughter of the person whose on-the-spot movie documented the fatal shot. We also consider a range of dramas that are based on scientific themes, such as Tom Stoppard's Arcadia and Michael Frayn's Copenhagen. [ more ]

ASTR 402(F) TUT Between the Stars: The Interstellar Medium

The matter between the stars--the interstellar medium--tells the story of the evolution of galaxies and the stars within them. Stars are accompanied by diffuse matter all through their lifetimes, from their birthplaces in dense molecular clouds, to the stellar winds they eject as they evolve, and to their final fates as they shed their outer layers, whether as planetary nebulae or dazzling supernovae. As these processes go on, they enrich the interstellar medium with the products of the stars' nuclear fusion. Interpreting the emission from this interstellar gas is one of astronomers' most powerful tools to measure the physical conditions, motions, and composition of our own galaxy and others. In this course we will study the interstellar medium in its various forms, from cold, dense, star-forming molecular clouds to X-ray-emitting bubbles formed by supernovae. We will learn about the physical mechanisms that produce the radiation we observe, including radiative ionization and recombination, collisional excitation of "forbidden" lines, collisional ionization, and synchrotron radiation. Applying our understanding of these processes, we will analyze the physical conditions and chemical compositions of a variety of nebulae. Finally, we will discuss the evolution of interstellar material in galaxies across cosmic time. This course is observing-intensive. Throughout the semester, students will work in small groups to design, carry out, analyze, and critique their own observations of the interstellar medium taken using the rooftop telescope. [ more ]

ASTR 404(S) TUT Unsolved Problems in Galaxy Evolution

In this tutorial, we will learn about galaxies and their evolution by focusing on some of the key mysteries astronomers are trying to solve. Questions may include: How do galaxies turn their gas supply into stars? Is there a universal initial mass function for star formation? What is the origin of multiple stellar populations in globular clusters? Why do some galaxies cease star formation? Which galaxies reionized the universe? We will discuss the nature of each unsolved problem, debate the theories proposed to answer it, and consider how future progress might be made. [ more ]

ASTR 410 LEC Compact Stellar Remnants: White Dwarfs, Neutron Stars and Black Holes

Last offered Spring 2023

A star is a very interesting, very complicated physical object. Properties of stars and their evolutionary paths depend on an intricate interplay of different physical phenomena with gravity, nuclear interactions, radiation processes and even quantum and relativistic effects playing important roles. Using basic physics we will construct simple models of stars and discuss their evolution, concentrating on the key physical processes that play the dominant role at different evolutionary stages. We will discuss late stages of stellar evolution and concentrate on the basic properties of three possible remnants: white dwarfs, neutron stars and black holes. Radio and X-ray pulsars, supernovae including Type Ia and Gamma Ray Bursts will be discussed as well as observational confirmation of existence of black holes. We will explore extreme conditions existing near neutron stars and black holes and discuss their astrophysical consequences. We will also discuss the recent exciting detection of gravitational waves by the LIGO/VIRGO laser interferometric detectors. [ more ]

ASTR 493(F) HON Senior Research: Astronomy

An original experimental or theoretical investigation is carried out under the direction of a faculty member in Astronomy, as discussed under the heading of the degree with honors in Astronomy above. This is part of a full-year thesis (493-494). [ more ]

ASTR 494(S) HON Senior Research: Astronomy

An original experimental or theoretical investigation is carried out under the direction of a faculty member in Astronomy, as discussed under the heading of the degree with honors in Astronomy above. This is part of a full-year thesis (493-494). [ more ]

ASTR 495 HON Senior Research: Astrophysics

Last offered Fall 2022

An original experimental or theoretical investigation is carried out under the direction of a faculty member in Astronomy or Physics, as discussed under the heading of the degree with honors in Astrophysics above. [ more ]

ASTR 496 HON Senior Research: Astrophysics

Last offered Spring 2022

An original experimental or theoretical investigation is carried out under the direction of a faculty member in Astronomy or Physics, as discussed under the heading of the degree with honors in Astrophysics above. [ more ]

Taught by: Jay Pasachoff

Catalog details

ASTR 498(S) IND Independent Study: Astronomy or Astrophysics

Astronomy/Astrophysics independent study, directed by one of the Astronomy faculty: Pasachoff/Jaskot/Flaherty [ more ]

ASTR 499(F, S) LEC Physics and Astronomy Colloquium

Physicists and Astronomers from around the country come to explain their research. Students of Physics and Astronomy at any level are welcome. Registration is not necessary to attend. A non-credit course. [ more ]