The Chester County Astronomical Society was formed as a non-profit organization dedicated to the education and enjoyment of astronomy for the general public. The Society holds meetings (with member or guest speakers) and observing sessions once a month. Anyone who is interested in astronomy is welcome to attend meetings and become a member of the Society. In addition to the monthly meetings and observing sessions, the Society also provides a variety of services to the public, including astronomy classes as well as telescopes and expertise for "star parties" for school, scout, and other civic groups.

• Friday, September 4, 2026 - CCAS Monthly Observing Session, Myrick Conservancy Center, BRC. The observing session starts at sunset (Rain date: September 5, 2026). For more information, contact our Observing Chair, Don Miller.
• Tuesday, September 8, 2026 - CCAS Monthly Meeting, in person (as well as via Zoom) at West Chester University�s Merion Science Center, Room 112. Our guest speaker is Dr. Theodore Kareta, Department of Physics, Villanova University. His presentation is titled "Visitors or Neighbors?: The Origin and Properties of the Quasi-Satellites and 'Mini-Moons� of the Earth."
• Wednesday, September 9, 2026 - Downingtown Library Solar Wednesday, 10:00 a.m.-12:00 p.m. EDT. For more information, contact our Observing Chair, Don Miller.
• Saturday, September 12, 2026 - Downingtown Library Solar Saturday, 10:00 a.m.-12:00 p.m. EDT. For more information, contact our Observing Chair, Don Miller.
• Tuesday, September 15, 2026 - Middletown Free Library Solar Tuesday, 2:00 p.m.-3:30 p.m. EDT. For more information, contact our Observing Chair, Don Miller.
• Thursday, September 17, 2026 - Kennett Library Solar Observing Session, Kennett, PA, 2:00-4:00 p.m. EDT. For more information, contact our Observing Chair, Don Miller.
• Friday, September 18, 2026 - CCAS Special Observing Session: International Observe the Moon with the WCU Mather Planetarium, 8 p.m. EDT to 10 p.m. EDT. For more information, contact our Observing Chair, Don Miller.
• Saturday, September 19, 2026 - Downingtown Library Solar Saturday, 10:00 a.m.-12:00 p.m. EDT. For more information, contact our Observing Chair, Don Miller.
• Saturday, September 19, 2026 - CCAS Special Observing Session: International Observe the Moon Night, West Chester Courthouse steps, 6 p.m. EDT to 10 p.m. EDT. For more information, contact our Observing Chair, Don Miller.
• Tuesday, September 22, 2026 - Middletown Free Library Solar Tuesday, 2:00 p.m.-3:30 p.m. EDT. For more information, contact our Observing Chair, Don Miller.
• Wednesday, September 23, 2026 - Downingtown Library Solar Wednesday, 10:00 a.m.-12:00 p.m. EDT. For more information, contact our Observing Chair, Don Miller.

The Moon joins a tea party, Venus reaches peak brilliance, the seasons change, and the Harvest Moon meets up with some planetary neighbors. From September 14 through 20, use the Moon as a guide to spot Antares, the Teapot asterism, and � under especially dark skies � the center of our Milky Way galaxy. On September 18, look low in the west shortly after sunset as Venus reaches peak brilliance for this evening appearance. On September 19, celebrate International Observe the Moon Night! People around the world are invited to look up and connect with our nearest celestial neighbor while learning more about lunar science, exploration, and the many ways the moon has shaped cultures around the world. The September equinox arrives on September 22, marking the start of fall in the Northern Hemisphere and spring in the Southern Hemisphere. Then on September 26, the Harvest Moon rises near Saturn, with faint Neptune completing a wide triangle in the sky. Saturn is visible to the unaided eye, while Neptune requires binoculars or a telescope. Additional information about topics covered in this episode of What's Up, along with still images from the video, and the video transcript, are available at https://science.nasa.gov/skywatching/whats-up/

For star parties and astronomy events near you, visit http://nightsky.jpl.nasa.gov/. Learn about all of NASA's missions at http://www.nasa.gov/.

Astronomers may have found one of the strangest objects ever detected: Cloud-9, a possible starless galaxy dominated by dark matter. Located about 14 million light-years away near Messier 94, Cloud-9 contains roughly one million solar masses of neutral hydrogen � but Hubble could not find the stellar population expected inside a normal dwarf galaxy. Then, in August 2026, astronomers used the Gran Telescopio Canarias to look roughly ten times deeper than previous deep optical imaging. Once again, the expected stellar glow was missing. So what is holding Cloud-9 together? One leading explanation is that Cloud-9 is a Reionization-Limited H I Cloud, or RELHIC � a dark matter halo that collected gas in the early universe but never managed to form a normal population of stars. Models suggest the object could exist inside a dark matter halo containing billions of solar masses. If confirmed, Cloud-9 could become one of the cleanest laboratories ever found for studying dark matter � and could reveal an entire hidden population of failed galaxies that traditional optical telescopes were never able to see. In this video, we explore the Cloud-9 starless galaxy, the latest Hubble and Gran Telescopio Canarias observations, dark matter halos, failed galaxies, RELHICs, cosmic reionization, and what this discovery could mean for our understanding of galaxy formation. Paperlink : https://arxiv.org/pdf/2607.06712

Visit our website for up-to-the-minute updates: www.nasaspacenews.com.

The society schedules monthly observing sessions in the Myrick Conservation Center of the Brandywine Red Clay Alliance. The observing sessions, which are planned around the new moon, are open to the public and announced in the Society's newsletter, Observations. Owning a telescope or binoculars is not required; anyone interested in observing the heavens is welcome to show up. If you do have a telescope and need help using it, our observing sessions are a great place to practice and learn from other society members.

The Chester County Astronomical Society's regular monthly meetings include a presentation from an invited speaker or the demonstration of an astronomical project by one of the Society's members. After the presentation, a brief business session is held to review the status of society activities. Meetings typically last 1-1/2 to 2 hours including an informal conversation over refreshments before the start of each meeting.

The Society meets at 7:30 PM the second Tuesday of each month in the Merion Science Center (former Boucher Building) at West Chester University (corner of South Church Street and Rosedale Avenue, West Chester, Pennsylvania). Click for Directions and Maps.

CCAS has partnered with Chester County Lifelong Learning to offer a six-week program meeting in the spring of 2026. For more information, including dates of the classes, contact our Education Co-Chairs. Learn more about the location, the topics covered, and how to register on the classes page.

The Chester County Astronomical Society offers "nights out" to interested organizations including local schools, scouting groups, and other civic groups for the purpose of learning more about the heavens. For example, scouting groups often hold them to earn badges for their members. If your organization is interested in hosting a "night out", please contact us.

• Friday, September 4, 2026 - CCAS Monthly Observing Session, Myrick Conservancy Center, BRC. The observing session starts at sunset (Rain date: August 15, 2026). For more information, contact our Observing Chair, Don Miller.
• Wednesday, September 9, 2026 - Downingtown Library Solar Wednesday, 10:00 a.m.-12:00 p.m. EDT. For more information, contact our Observing Chair, Don Miller.
• Saturday, September 12, 2026 - Downingtown Library Solar Saturday, 10:00 a.m.-12:00 p.m. EDT. For more information, contact our Observing Chair, Don Miller.
• Tuesday, September 15, 2026 - Middletown Free Library Solar Tuesday, 2:00 p.m.-3:30 p.m. EDT. For more information, contact our Observing Chair, Don Miller.
• Thursday, September 17, 2026 - Kennett Library Solar Observing Session, Kennett, PA, 2:00-4:00 p.m. EDT. For more information, contact our Observing Chair, Don Miller.
• Friday, September 18, 2026 - CCAS Special Observing Session: International Observe the Moon with the WCU Mather Planetarium, 8 p.m. EDT to 10 p.m. EDT. For more information, contact our Observing Chair, Don Miller.
• Saturday, September 19, 2026 - Downingtown Library Solar Saturday, 10:00 a.m.-12:00 p.m. EDT. For more information, contact our Observing Chair, Don Miller.
• Saturday, September 19, 2026 - CCAS Special Observing Session: International Observe the Moon Night, West Chester Courthouse steps, 6 p.m. EDT to 10 p.m. EDT. For more information, contact our Observing Chair, Don Miller.
• Tuesday, September 22, 2026 - Middletown Free Library Solar Tuesday, 2:00 p.m.-3:30 p.m. EDT. For more information, contact our Observing Chair, Don Miller.
• Wednesday, September 23, 2026 - Downingtown Library Solar Wednesday, 10:00 a.m.-12:00 p.m. EDT. For more information, contact our Observing Chair, Don Miller.

Star parties are national and regional events similar to "nights out" and open to the public. They are held throughout the year. For a list of upcoming national events in 2026, visit the star parties page.

The West Chester University Department of Geology & Astronomy hosts a planetarium show open to the general public on the 2nd Friday of each month. The WCU Planetarium is located in the Schmucker Science Center on Church St. To locate the planetarium, view the campus map.


The shows start promptly at 7:00 P.M. ET and run approximately one hour in length. Late arrivals will not be permitted to enter the planetarium. Each show includes an overview of what is visible in the current night sky and a special focus on some aspect of astronomy.

Reservations are required because the planetarium has limited seating. For contact information, visit the WCU Public Planetarium Shows webpage.