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Rittenhouse Astronomical Society

An astronomy society founded in 1888 that runs public talks with guest speakers and keeps the public posted through a mailing list.

  • Newcomers welcome
  • Online OK

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What they do

Come to a public open house at Ryan Observatory, usually on the second Saturday evening, or to one of the city nights at Columbus Recreation Center. Members get dark-sky observing, virtual access to the monthly meetings, and a free seat at the telescope workshop.

Who it is for

Who can join
Open to anyone
Who is there
Adults of any age

When and where

Public open houses at Ryan Observatory fall on the second Saturday of most months, starting at 7:15 pm. Observing nights at the observatory are scheduled around sunset, weather permitting.

Days
Saturday
Times
Evening

Ryan Observatory, Muddy Run Park, Holtwood, PA

Meets outside the city and serves Philadelphia.

Columbus Recreation Center, 8th and Wharton, Philadelphia

You can join online.

Your first visit

Feeling unsure the first time is normal. Most groups are glad when someone new walks in.

First step: Come to a public open house at Ryan Observatory on a second Saturday evening. The next one is Saturday, October 10, 2026, starting at 7:15 pm. No registration is listed for open houses, and the contact page offers a mailing list for updates..

You can just show up.

What to expect

Open houses run from 7:15 pm to about 10 pm, usually with a talk or themed program at the observatory. Observing nights depend on the weather, so check the events page before you go. The observatory is in Muddy Run Park in Holtwood, outside the city, so plan your ride ahead.

Tips for your first visit

  • Check the events page the week before, since observing nights depend on the weather.
  • Plan transport to Holtwood, since the observatory is outside the city.
  • The telescope workshop is free for members and needs a ticket for non-members, so ask about it if you want hands-on learning.

Newcomer welcome

Welcoming to newcomers (4 out of 5). Why we say this: Open houses are public with no registration listed, the society says no experience is needed to attend, and it runs telescope workshops that non-members buy a ticket to..

Cost and commitment

Cost
Cost not known yet. Open house prices are not listed. Yearly membership is $50 (Star), $75 (Supernova) or $350 (Quasar). Members get the telescope workshop free, and non-members buy a ticket.
How often
About once a month

Access and languages

Wheelchair access
We do not know yet. Ask the group before you go.
Languages spoken
We do not know yet which languages are spoken.

Requirements

We found no special requirements. Ask the group if you are not sure.

How to reach them

We copy contact details as the group or a public source published them. Each one shows where it came from.

Sources and last check

Checked by our research team on October 8, 2026. This was a closer look, including what a first visit is like.

Last seen active
September 2026 (See the evidence)
Last checked by our team
October 8, 2026
Status
Active
Our confidence in this listing
Medium
  • rasphilly.org, seen October 8, 2026. Supports: Summary, First step, Contacts
  • nightsky.jpl.nasa.gov, seen October 8, 2026. Supports: Schedule
  • rasphilly.org, seen October 8, 2026. Supports: Location, First step
  • rasphilly.org, seen October 8, 2026. Supports: Schedule, Location, Status, First step, Cost
  • rasphilly.org, seen October 8, 2026. Supports: Cost, First step, What they do

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