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FOAP Newsletter September 2025 |
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President's Message
Dear Members - Welcome to September! This month arrived quietly yet is always such a full and busy time. The Friends have an ambitious Fall season ahead for our members and community, with public shows planned for each month at the Planetarium plus many ongoing and new activities and public outreach events. Lots of details are shared in this newsletter and remember to check FOAP’s website for updates and new program information.
This summer kept your FOAP Board and volunteers quite busy, engaging in community outreach events, adding a very popular July public show weekend, and returning to the Arlington County Fair where we featured FOAP’s portable planetarium dome. Read more about this event, and other FOAP doings below.
Did you know? FOAP established the Accessible Planetarium Project over this past year, debuting at the Arlington County Fair. The project uses a virtual reality (VR) experience designed to run concurrently with our portable dome shows, providing an equitable and inclusive experience for those with mobility, sensory, or language barriers. The VR station was extremely popular, and the public response was overwhelmingly positive, confirming the need for and success of this initiative. Funding for the Accessible Planetarium Project was made possible by grants from The Arlington Community Foundation, The Quad Cities Community Foundation, Arlington County’s Neighborhood Mini-Grant program, and your generous support.
A few reminders for members…
Watch for a Member Survey in your inbox next week. We want to hear your ideas and suggestions about FOAP programming during our public planetarium weekends.
Join us at FOAP’s Member Picnic on Sunday, September 14 at Hayes Park. Details below! We hope many of you will add a stop at our picnic to your busy day!
Plan to attend our September Public Show Weekend. FOAP is supporting AFAC over this next year by collecting donations from show attendees each month. Please consider bringing food items to donate when you attend an FOAP weekend show.
I look forward to saying hello at the Planetarium! Theresa Carroll Schweser
FOAP President |
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Let’s Have a Picnic! By Kathi Overton
We love to get together with our members, and we hope that you will join us at our free Member Appreciation Picnic on Sunday, September 14. FOAP will be at the main picnic shelter at Hayes Park, rain or shine, from 2pm to 4 pm. Beverages, chips and a taco bar will be provided. You are welcome to bring desserts or side dishes to share. There will be family friendly activities, and information will be available regarding upcoming FOAP events.
Hayes Park is located at 1516 N Lincoln St, Arlington, VA 22201, only a few blocks from the Arlington planetarium. The parking lot is limited, though there is street parking nearby. |
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FOAP Brings the Stars and Planets to the Arlington County Fair By Kathi Overton
Did you visit the portable planetarium dome at the Arlington County Fair this year? Over the course of three very full days, a dedicated group of volunteers from FOAP presented 83 shows to a total audience of 1377 people! The fair also marked the debut of our new VR headset system, which enables individuals with mobility limitations to experience immersive video even if they are unable to enter the dome. Read more about the Fair and our portable dome on ArlNow.
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The portable dome at the 2025 Arlington County Fair.
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A view from inside the portable dome. Photos: Peter Roof |
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David M Brown Public Planetarium Shows for September!
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Planetarium Shows Are Back!
As we welcome all the students back to school this Fall, the Friends of Arlington’s Planetarium (FOAP) are preparing a fall lineup of public shows at the David M. Brown Planetarium. One weekend per month FOAP will host programs for the public on Saturday evening at 6pm and 7:30pm (note the new times!). There will also be shows on Sunday afternoon at 1:30pm and 3:00pm.
Tickets for the shows will be available for purchase online 2 weeks in advance, and a few tickets for each show will be held for sale at the door.
September will feature four different fulldome planetarium shows:
9/20/25 at 6pm The Great Solar System Adventure
9/20/25 at 7:30pm Supermassive Black Holes
9/21/25 at 1:30pm 3-2-1 Liftoff!
9/21/25 at 3:00pm Moonbase: The Next Step
Be sure to check out our website to find the entire school year schedule, as well as specifics about upcoming shows:
Schedule of show dates for the school year
https://friendsoftheplanetarium.org/sys/website/?pageId=18218
Calendar with information about upcoming events: https://friendsoftheplanetarium.org/sys/website/?pageId=18237 |
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System Updated at the David M. Brown Planetarium By Kathi Overton
Just before the start of school, the Arlington planetarium’s computer system was upgraded to the latest version of Digistar. Digistar is a powerful software program that runs the dome’s sky simulator and plays back fulldome films. This latest version is more versatile and provides more detailed views of the solar system and the galaxy. There is also new artwork for constellations, and the system can now show 3D views of many places here on Earth. We will be testing the new capabilities of the system, and hope to utilize them during future sky talks. |
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Planetarium Specialist Mary Clendenning at the controls.
Photo: Jim Thorne |
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WATCH THIS SPACE! By Dawn Darling
If you are reading this, you may know that the Kids Corner was created last year FOR KIDS, BY KIDS. The planetarium started a Student Advisor program last year and articles for this space were written by high school students for our younger audience. This year we will soon welcome our SECOND cohort of students! |
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You can learn more about the program in our October newsletter, as well as enjoy articles throughout the year by our student advisors. Because we are a fun group, we hope you enjoy some games and puzzles as well.
Thanks for reading and I hope you check back with us next month to learn about the program and enjoy fun, new content.
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Jokes for Kids Only!
Q. What do you call a comet wrapped in bacon?
A. Meat-eor!
Q. What really makes an astronaut’s day?
A. The sun’s rotation!
Q. Where do astronauts keep their food?
A. In their launch boxes!
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What's in the Sky this Month By Mike Rhee |
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The month of September brings an unmistakable feel of autumn in our area. Evening darkness arrives sooner and there is a noticeable chill in the air after sunset. Those carefree summer days at the beach and long evening walks at the park feel like distant memories. Read More...
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Saturn in September
By Jennifer Bartlett
This month is an excellent opportunity to view Saturn. It will reach opposition on September 21 at 2 AM EDT; at that time, it will be on the opposite side of the Earth from the Sun. On that day, it will rise at sunset and set at sunrise. It will also be closest to us and its disk will appear largest to us.
At the beginning of the month, Saturn will rise in the east about 2 hours after sunset and be highest in the sky after midnight. However, it will rise earlier each evening. You will continue to see Saturn in the evening sky through February.
To the naked-eye, Saturn is the brightest object in the evening sky. Mars is fainter and redder; it will set in the west before 9 PM EDT. In the mornings, Jupiter and Venus are brighter.
Through binoculars, Saturn will broaden into more of an oval disk; its legendary rings will not be distinct. A telescope will reveal thin rings. At opposition, we will see the rings titled 2 degrees instead of viewing them edge-on as we did back in March. When observed edge-on, the rings seemed to disappear.
On September 4 and 20, those with access to telescopes have opportunities to watch the shadow of Titan, Saturn’s largest moon, cross in front of its gas giant host. The transits begin at 1:25 and 1:09 AM EDT and last until 4:50 and 3:34 EDT AM, respectively. We only see the shadow of Titan cross Saturn when our planet is nearly in the same plane as Saturn. This alignment occurs every 15 years and is also associated with seeing the rings edge-on. After this month, we will be waiting more than a decade for our next full opportunity. |
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Neptune, a New Planet By Jennifer Bartlett
On the night of September 23-24, 1846, Johann Gottfried Galle (1812-1910) at the Berlin Observatory detected the planet we know as Neptune through the 9-inch telescope there. He was working from positions computed by French astronomer Urbain Le Verrier (1811-1877) who hypothesized that a second new planet could explain irregularities in the orbit of the recently discovered Uranus. A less successful British team was also investigating this problem: theorist John Couch Adams (1819-1892), James Challis (1803-1882) at Cambridge Observatory, and George Airy (1801-1892), Astronomer Royal at Greenwich. Challis probably saw Neptune in August but mistook it for a star.
William Herschel (1738-1822) had previously found Uranus in 1781, expanding the Solar System to six, seven if you count Earth, planets. Newton’s Laws were proving to be powerful tools for describing and predicting natural phenomena. However, later analysis determined that Galle and Adams poorly estimated the distance from the Sun to Neptune. Therefore, their calculated positions would have performed poorly elsewhere along Neptune’s orbital path.
Although Voyager 2 in 1989 is the only spacecraft to visit Neptune, large ground-based telescopes as well as the Hubble and James Webb Space Telescopes have observed it. It is a ice giant with 14 known moons, the largest of which is Triton. It has five relatively young rings. In 2016, Hubble detected a new dark spot, an atmospheric vortex in the atmosphere of Neptune. We still have so much to learn about this distant world.
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Ocean Worlds Abound By Jennifer Bartlett
Our blue marble world is distinctive in the Solar System for its Solar System for its surface oceans visible from outer space. We associate the presence of liquid water with habitability and place water at the center of our quest for life beyond Earth. Scientists speculate the Mars and Venus may have been wetter and more hospitable in their distant past. More intriguing still are the suggestions that other Solar System bodies may also have reservoirs of water.
Europa, a moon of Jupiter, may have a salty ocean beneath its icy surface. As Europa orbits Jupiter, it experiences tides. As the tides stress and flex Europe, the friction generates heat. Hubble may have imaged water spewing forth from the surface. The Europa Clipper mission will tell us more when it arrives in 2030.
Ganymede, the largest moon of Jupiter, is also subject to tidal heating like Europa. It may a salty underground ocean or layers of subsurface ice and water.
Callisto, a moon of Jupiter slightly larger than Europa, has a rocky crust that probably lies on top of a layer of ice which in turn covers liquid water. Again, the water remains liquid through tidal heating.
Enceladus, a moon of Saturn, was detected venting water, organic molecules, and silicates from its surface by the Cassini mission in 2005. A subsurface ocean, possibly with hydrothermal vents similar to those on Earth’s ocean floor, is feeding the plume ejected material.
Titan, the largest moon of Saturn, is the only Solar System moon with a substantial atmosphere; it is denser than the terrestrial atmosphere with its own weather. However, with a surface temperature around -300 F (-200 C, 100K) the seas, lakes, and rivers on its surface are liquid methane and ethane, which would be gasses on Earth. About 30 miles (50 km) below the surface, a salty liquid water ocean may exist.
Mimas, Deathstar-looking moon of Saturn, may have a subsurface ocean or a core that is more football (ellipsoidal) than spherical.
Triton, the largest moon of Neptune, has geysers of liquid nitrogen and ice volcanoes. A subsurface ocean of water is a possibility, but still very speculative.
Pluto, Kuiper Belt Object, has an active surface for a world with a surface temperature around -400 F (-230 C, 40K) including surface fault lines, mountains of water ice, and glaciers of nitrogen and methane ice. These features suggest it may also be hiding an ocean within its depths.
With some many ocean worlds so close to home, how many possibilities must lie beyond our borders? |
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This message has been sent to you from the Friends of Arlington's Planetarium.
Friends of Arlington's David M. Brown Planetarium
P.O. Box 7029
Arlington, VA 22207 USA
Copyright (C) 2025 Friends of Arlington's David M. Brown Planetarium (FOAP). All rights reserved.
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