Register below!
Free course for AAA members
Basics of Stars, Galaxies, Cosmos (2025)
(Formerly Astronomy 102)
Wednesdays, 7-9 PM ET, online. Jan.29; Feb. 5, 12, 19, 26; March 5
What lies beyond the solar system? The universe is filled with a fantastic assortment of objects, from the bright and active to the dark and mysterious. In this course, we’ll explore core principles of astronomy, such as gravitation, properties of light, and light travel-time. We’ll survey a variety of celestial bodies and discusses how astronomers gather information to learn about the cosmos. Beginning with stars we’ll journey out to the rest of the Milky Way Galaxy, other galaxies, and beyond. Along the way, we’ll explore how astronomers measure the vast distances to these far-off objects.
This is an introductory-level, conceptual course. No previous knowledge of astronomy is required. We won’t get into deep details or mathematical equations. If requested, supplementary material may be referenced for any who want to go deeper into the topics.
We do not cover anything inside our solar system or other planetary systems (planets, moons, exoplanets, comets, exobiology, etc.). A companion course Astronomy 101 does that in the fall. It does not cover sky-mapping, purchasing and using telescopes, and constellations. We touch on some astronomical FAQ’s such as dark matter, dark energy, and black holes. The course uses Zoom, a free online service.
Course Outline
January 29 – Intro to the Universe, and Light
A survey of the universe beyond the solar system – what’s out there and how do we learn about
it? An introduction to astronomical units for distance and the “distance ladder,” starting with
parallax. Some telescope basics: aperture, resolution, and the importance of location.
February 5 – Light and Stars
Properties of light, including wavelength, frequency, and velocity. Types of spectra, black body
radiation and temperature. Sorting stars by temperature and luminosity on the HR Diagram.
Next rung of the distance ladder: spectroscopic parallax.
February 12– Gravity and Stars
Gravitation, from Newton and Einstein, and its influence on stellar evolution. “Extreme stars,”
including neutron, pulsars, dwarfs, black holes. Introduction to gravitational waves and
gravitational redshift. Preview another rung on the ladder: Type 1a supernovae.
February 19 – The Milky Way
Types of star clusters and nebulae, and where they’re found in the Milk Way. Anatomy of the
Milky Way Galaxy: bar, disk, halo. Introduction to doppler redshift, radial velocities, dark
matter. Next rung on the distance ladder: Cepheids and other variable stars.
February 26 – Galaxies
Hubble’s Tuning Fork, the Local Group, galactic interactions. Galaxy clusters, more dark matter,
large-scale structure. Climbing the ladder to doppler redshift and Type 1a supernovae, we reach
the expansion of the universe and the Hubble Constant.
March 5 – Beyond the Galaxies
The icing on our cosmic cake: what lies in the farthest reaches of our observable universe?
Quasars, cosmological redshift, the Big Bang, cosmic microwave background radiation, the size
and age of the universe, and an introduction to dark energy.
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Instructor: Irene Pease earned her Bachelor’s degree in Physics at the University of Arizona. As
Your Friendly Neighborhood Astronomer she has hosted weekly and monthly livestreams covering a variety of astronomy topics. While living in NYC Irene produced the Hayden Planetarium video blog, Skylight, and was a frequent presenter and co-host of Astronomy on Tap NYC, and a presenter for Hayden Planetarium’s Astronomy Live series. Irene also taught physics and astronomy for NYC high schools and colleges. She currently co-hosts astronomy outreach events in Sullivan County and observes from the dark skies of the Catskills. She is a Hayden Associate. She has been an instructor in a number of AAA classes, co-host of our AAA-Sky podcast , and President of the AAA.
Register in the Tickets window below
No fee for members; $30 for non-members
After registering, you’ll receive a confirmation containing our Google Classroom (GC) link. Click on this GC link immediately to be listed on the class roster. (You need a non-edu email address.) The Google Classroom is used for lecture slides, supplementary materials, announcements, discussions between the instructor and classmates, and links to the class recordings. It also gives the key Zoom link to attend class each week after 6:50 PM.
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