Entry No. 25 — the Philadelphia file — filed under: night sky
Rittenhouse Astronomical Society — Columbus Square star parties
Founded in 1888, this is one of the oldest astronomy clubs in the country, and its members set up their own telescopes on a South Philly rec-center ballfield for free public star parties — a recent one had visitors looking at Saturn and a waxing gibbous moon, with an indoor backup plan of 'Stellar Jeopardy' and 'Luna, Name That Moon Tune' if clouds roll in.
The story
You might expect an astronomical society founded in 1888 to hide behind private dome observatories or high-altitude mountain peaks, but the Rittenhouse Astronomical Society does something far more democratic: they haul heavy optical glass straight onto a public rec-center ballfield in South Philly. On designated star-party nights, members of one of the country's oldest amateur astronomy clubs set up their personal tripods and high-powered reflectors on the grass at 12th and Wharton Streets, turning a Passyunk Square neighborhood park into a pop-up cosmic observatory.
Urban light pollution ought to ruin deep-sky viewing, but bright targets like Saturn's rings and the craters of a waxing gibbous moon cut right through South Philly's amber glow. Club members position their eyepieces and invite anyone walking past to take a look, freely sharing technical details about focal lengths and planetary orbits without a drop of academic pretension.
The genius of the setup is its rain-or-shine reliability. If thick cloud cover rolls in over Passyunk, the gathering simply migrates inside the Columbus Square Recreation Center for indoor space games—shifting without missing a beat into rounds of 'Stellar Jeopardy' and moon-themed music trivia like 'Luna, Name That Moon Tune.'
What it's like
Show up between 7:00 PM and 9:00 PM at 1200 Wharton Street and look for the cluster of tripods on the rec center field. The vibe is casual, multi-generational, and entirely free—you just walk up, wait a brief moment in line behind whichever telescope is pointed at something interesting, and take your turn at the eyepiece. If the sky is overcast, follow the group inside the rec center building for the indoor trivia contingency.
The move: Walk over on a clear-sky RAS star-party night, look through a stranger's telescope at Saturn's rings from a baseball infield, and stick around for the moon-themed trivia if it clouds over instead.
- 📍 Passyunk Square / South Philadelphia
- 💸 $
- ⚡ Low-key
- 🌗 Outdoors
Where: Columbus Square Recreation Center, 1200 Wharton St, Philadelphia, PA 19147
Hours: Added 2026-07-19 — confirm current hours before you go.
⚠ Seasonal or scheduled — always check before you go.
Pair it with
- Mario Lanza Institute and Museum — Located just a short walk north in Bella Vista, this intimate tribute to South Philly's famous tenor makes a delightfully idiosyncratic stop before nightfall.
- The 8th House — Combine practical observational astronomy on the ballfield with a visit to this Point Breeze shop dedicated to esoteric tools and local community events.
- Garland of Letters Bookstore — Browse South Street's long-running New Age bookstore for celestial and esoteric reads before viewing the actual planets through a telescope.
Good to know
Do I need to buy tickets or RSVP in advance?
No, the star parties are completely free, open to the public, and run on a walk-up basis.
What happens if the weather is cloudy or rainy?
The events run rain or shine from 7:00 PM to 9:00 PM. If clouds block the sky, the group moves inside the Columbus Square Recreation Center for astronomy trivia games.
Do I need to bring my own telescope?
No, Rittenhouse Astronomical Society members bring their personal telescopes specifically for visitors to look through.
Where in the park do they set up?
They set up outdoors on the ballfield area at Columbus Square Recreation Center, located at 12th and Wharton Streets.
Plan a visit & invite your people →
Further reading: rasphilly.org · nightsky.jpl.nasa.gov · Instagram
last checked: 2026-07-19