Twin City Amateur Astronomers

Public Observing Sessions

From April through October, the TCAA holds monthly observing sessions that are open to the public. These "star parties" are held at our observatory at the Sugar Grove Nature Center, a dark sky site southwest of Bloomington.

In 2022, we will hold the following observing sessions Additional prominent sky objects such as planets, nebulae, star clusters, and galaxies will be viewed when visible.

DateFeatured TopicTime
April 30Andromeda Galaxy & the Great Debate08:00PM - 10:00PM
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?
May 28Lunar & Solar Eclipses08:30PM - 10:30PM
An eclipse is the result of the total or partial masking of a celestial body by another along an observer's line of sight. Solar eclipses result from the Moon blocking the Sun relative to the Earth; thus Earth, Moon and Sun all lie on a line. Lunar eclipses work the same way in a different order: Moon, Earth, and Sun all on a line. In this case the Earth's shadow hides the Moon from view. We recently experienced a partial solar and total lunar eclipse. What does the remainder of 2022 hold for us?
June 25The Life Cycles of Stars09:00PM - 11:00PM
Stars are formed in clouds of gas and dust, known as nebulae. Nuclear reactions at the center of stars provide enough energy to make them shine brightly for many years. Stars remain stable for extended periods of time and then die in amazing explosions. The lifetime of a star depends mostly on its mass. Large, massive stars burn their fuel much faster than smaller stars and may only last a few hundred thousand years. Smaller stars, however, will last for several billion years, because they burn their fuel much more slowly.
July 30Meteors, Meteorites, & Meteoroids08:30PM - 10:30PM
Meteors, meteorites, and meteoroids… Think of them as “space rocks." When cosmic rubble known as meteoroids wing their way through outer space and then enter Earth's atmosphere at high speed and burn up, the fireballs or “shooting stars” are called meteors. When a meteoroid survives a trip through the atmosphere and hits the ground, it's called a meteorite. Learn more about these smallest denizens of the solar system and when and where to see them in the sky and on the Earth.
August 27Constellations & the Stories Behind Them08:30PM - 10:30PM
Constellations are formed of bright stars that appear close to each other on the sky but are very far apart in space. Many societies saw patterns among the stars with gods and goddesses or stories from their culture. Most of the constellations with which we are familiar come from ancient Greece, but other civilizations created their own patterns in the sky based on stories and people that were important to them. We look up today and see the stars divided into the same familiar patterns as our ancestors, but how did the constellations come to be?
September 24Uranus & Neptune07:30PM - 09:30PM
Uranus and Neptune are the two most distant major planets in our solar system. Both are considered ice giants. Both are fundamentally different from the larger gas giants Jupiter and Saturn, and from smaller rocky worlds like Earth. We tend to lump Uranus and Neptune together in our thoughts, almost as if they’re twin worlds. They are nearly the same size – bigger than Earth, but smaller than Jupiter or Saturn – and both are bluish or bluish-green, with deep atmospheres and icy interiors. Though superficially similar, Uranus and Neptune are really quite different.
October 22The James Webb Space Telescope07:00PM - 09:00PM
The James Webb Space Telescope (JWST) is an orbiting infrared observatory that is now working to will complement and extend the discoveries of the Hubble Space Telescope. This new telescope uses longer wavelength coverage (infrared) and has greatly improved sensitivity. The use of infrared wavelengths enables the JWST to look much closer to the beginning of time and to hunt for the unobserved formation of the first galaxies, as well as to look inside dust clouds where stars and planetary systems are forming today.

A Typical Public Viewing Session includes:
  • Lecture about the featured object.
    This 20-30 min. presentation, held in the SGNC picnic shelter, includes images of and details about the featured sky object as well as information on other interesting celestial objects that might be viewed that evening.
  • Sky tour using a laser pointer.
    We step out under the stars to point out the major constellations and planets, and to designate the location of the featured celestial object for the evening.
  • Telescope observing session.
    We use members' telescope at ground level to observe the featured object and other wonders of the heavens.

You can download our 2022 Public Viewing Session brochure.

If you would like to arrange a special event for your group, please follow this link to Request a Special Event.