Twin City Amateur Astronomers

Welcome to the TCAA

Welcome to the Twin City Amateur Astronomers' web site.

Located in the twin cities of Bloomington and Normal, Illinois, the TCAA was formed in 1960 to share our love of astronomy.

The purposes for which the TCAA is formed are: to promote in every way among its members and the general public an interest in, and knowledge of, astronomy and its allied sciences; to advance amateur astronomy and observational techniques; to render assistance to other individuals or organizations working in the same or related fields; and to do everything necessary and proper to further such on a formal or informal basis.

On this site you can find out about us, about our public observing sessions, held at our dark sky observatory southwest of Bloomington; our public presentations, which take place at a variety of venues usually in the Bloomington-Normal area; and even peruse our award-winning newsletter, The Observer.

Our next Event...

Andromeda Galaxy & the Great Debate

When Saturday, April 30, 2022 8:00 PM - 10:00 PM
Status Scheduled
Where Sugar Grove Nature Center
What The Great Debate was held on April 26, 1920, between the astronomers Harlow Shapley and Heber D. Curtis. It concerned the nature of so-called spiral nebulae and the size of the universe. Shapley believed that distant nebulae were relatively small and lay within the Milky Way, while Curtis held that they were in fact independent galaxies, implying that they were exceedingly large and distant. Which is it?

We are a 501c(3) non-profit organization. All contributions are tax deductable.

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