ASTR 104
The Milky Way Galaxy and the Universe Beyond Spring 2023
Division III

It has been less than a century since the Sun was discovered not to be at the center of the Milky Way Galaxy, and the Milky Way Galaxy was determined to be only one of countless “island universes” in space. A host of technological advances is enabling us to understand even more clearly our place in the universe and how the universe began. For example, the recently discovered “chirp” from gravitational radiation (reported in 2016) resulting from two giant black holes merging, and the “chirp” from two neutron stars merging, also producing light, radio and x-ray radiation, has opened a whole different way of observing the Universe from the traditional use of light and other forms of electromagnetic radiation. With dozens of such events recorded by 2022, we are now therefore in the new era of multimessenger astronomy. Further, the Hubble Space Telescope and the Chandra X-ray Observatory bring exceptionally clear images over a wider range of the spectrum; their images are aiding astronomers to better understand the past and future of the Universe, and new infrared images are expected by the time of this course from NASA’s James Webb Space Telescope. JWST observations starting with summer 2022, with those and other new telescopes on the ground (Vera Rubin Observatory) and in space (Nancy Grace Roman Space Telescope) help to confirm and enlarge our understanding of the Big Bang and the early epochs of the Universe. In addition, study of the early Universe (most recently from the Planck spacecraft) and large-scale mapping programs such as the Sloan Digital Sky Survey, the European Space Agency’s Gaia, and the Dark Energy Survey. Astronomy 104, a non-major, general introduction to part of contemporary astronomy comprising the study of galaxies and the Universe, explores the answers to questions like: What is the Milky Way?; Why are quasars so luminous?; Is the Universe made largely of “dark matter” and “dark energy”?; What determines the ultimate fate of the Universe? How have studies of Cepheid variables and distant supernovae with the Hubble Space Telescope determine that the Universe is 13.8 billion years old and indicated that the Universe’s expansion is accelerating? How significant is the current discrepancy between the age and expansion rate of the Universe as measured from supernova observations as opposed to measurements from the cosmic background radiation? 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 and 102, and students who have taken those courses are welcome.