Gardens of the Galaxy: Art of Science Learning Play Day!


The Cool Star Lab and volunteers from the Physics Dept. created its second public installation of a Pop-Up Galaxy Garden during the July 24th Art of Science Learning (AoSL) Play Day in Balboa Park. We were granted a prime site for this event, right in the middle of the historic Plaza de Panama in front of the San Diego Museum of Art. The event, organized by AoSL’s Nan Renner and funded by the Museum of Art and Panama 66, aimed to bring together educators and education enthusiasts from around the region to learn about and play with each other’s projects, and make connections.

This event was a big step up from the first Pop-Up at the San Diego Air & Space Museum on Space Day, which was only 12′ x 12′ (about 13 sq. meters). This time, we had 10 m x 10 m (100 sq. meter) to work with, an order of magnitude increase in area (note: this is still an order of magnitude smaller in area than Jon Lomberg‘s original Galaxy Garden). The larger area meant visitors could actually walk in and around the Galaxy.  However, it also meant more materials to bring, setup and teardown, which had to happen on the day.  Oh, and we had a $350 budget. How in the galaxy do we do this?


First we needed a design plan.  You would think that after studying billlllions of galaxies in the Universe, we astronomers would know the shape of our galaxy extremely well. But in fact, it’s very hard to measure the structure of our Galaxy partly because we are in it, and partly because most of our Galaxy is obscured from view by gas and dust in its plane. Most studies rely on mapping the motion of Hydrogen gas as it orbits the Galaxy. Unfortunately, we can only measure one dimension of this motion – the Doppler shift toward and away from us – and converting motion into distance requires some big assumptions about the distribution of mass in the Galaxy.  So we know a few things pretty well: we are in a spiral galaxy, our Sun is about 27,000 light-years from the center, and there is a central “bulge” region about 9,000 light-years across containing at its core a supermassive black hole. Things get fuzzy at the details, however. How many big spiral arms does the Galaxy have? (2? 4? 5? even or odd?) How continuous are those arms? What is the precise shape of the central region? (a spherical bulge? a bar? an X-shaped bar?).

Screen Shot 2014-08-25 at 12.36.05 AM

Model of the Galaxy from Hou et al. (2009) with 5 arms, based on H II emission

In the end, we chose to work from a conceptual map created by Dr. Robert Hurt of Caltech/IPAC, itself based on work by Prof. Bob Benjamin at U. Wisconsin-Madison, shown below. The scale gives us an even 100 lightyears/cm, which covers the the full 100,000 lightyear diameter of most of the visible Galaxy in our workspace.  Note that this still places most of the visible stars in the night sky within something the size of marble!

Screen Shot 2014-08-25 at 12.38.37 AM


What do we make the Galaxy out of, on the cheap? We were keen to keep the “garden” aspect intact, but we couldn’t plant on the Plaza, and couldn’t buy enough potted plants (as we did in the Space Day Pop-Up) to fill our space.  Our secret was to use cheap or found materials.

Here were our ingredients:

  • 100 square meters of landscape fabric
  • 200 meters of yarn
  • 36 cubic feet of red mulch (abotu 150 lbs.)
  • Four large garbage bags of seaweed collected the night before (about 100 lbs.)
  • 50 palm fronds
  • Paper for origami stars
  • Lots of arts & crafts materials for (pipe cleaners, glitter, spray glue, etc.)
  • A few donated hula-hoops
  • One cargo van


We had the fortune of working with local sculptor Stephanie Bedwell, who created the central piece, the Galactic bulge and the supermassive black hole at the center of our Galaxy. The latter was modeled as a black cornucopia (giving the “suck in” idea) with a tiny black gem at its center.  In fact, there is nothing small enough we could use to represent the actual “size” (or event horizon) of the central black hole, but artistic license was permitted!


We also had an amazing crew of very hard-working student volunteer from UCSD: Christian Aganze, Cami Bernal, Genevive Bjorn, Caleb Choban, Dianna Cowern, Zemus Diaz, Ivanna Escala, Tae Ha, Callen Hyland, Mike Lopez, Kelsey Lund (plus her brother), Saidou Ngaide, Andrew Nguyen, Melisa Tallis, Maitrayee Sahi, and Daniel Walsh, all of whom committed most of the day to the project.



The event was from 3:30-6:30pm, and most of us got to the Park (after laboring through Comic Con traffic) by 2pm, giving us a mere 90 minutes to set up.  Fortunately, our expert crew were on it, and we had the landscape backdrop  down pretty quickly. Stephanie went to work on the bulge, and we got a nice yarn grid in place to start laying out the sprial arms in red mulch. Once there were down, we laid down the palm fronds and the seaweed.




The setup was really hard work, due to the tight time constraints and weight of the materials. This was also on one of San Diego’s hottest days of the summer, and occurred during Ramadan, so some of our volunteers worked through hunger and thirst. The commitment of our volunteers was amazing!

Once the major elements were laid down, it was then up to our visitors to “seed” our garden with stars, nebulae, clusters, etc. We set up two tables of arts and crafts. One was devoted to origami “lucky stars”, one of the easiest origami pieces you can make. The other was devoted to our Galaxy’s “VIPs”: the most beautiful of the nebulae and clusters visible in our Galaxy.




Public interaction

The PlayDay Galaxy had a lot more interaction from the public than the Space Day one, largely because of its size and location.  You simply couldn’t miss it.  We also made sure to put up more information signs this time so folks knew what they were looking at and how they could participate. We have a few volunteers walk around to ask trivia questions about the Galaxy. But the most engaging aspect was the arts and crafts, which allowed kids and adults to add their own signature to the piece.





The event also made the news, with the Galaxy Garden prominently featured!

What worked, what didn’t

Overall, the installation went really well, with far more participation, curiosity and exploration by members of the public. Many of the volunteers learned something new about the Galaxy as well. Nevertheless, we could probably have better signage and pointers in the Galaxy. It wasn’t clear where some important places were (like our Sun), and the central bulge was a bit mysterious (although there were many selfies of people “falling into” the black hole). We could use a “Galactic Tour Guide” with a lot of knowledge – and personality.

On materials: no more collected seaweed, except on the beach.  We had several thousand sand fleas hitchhike along and participate unwillingly. While they provided a model for an “intergalactic civilization”, they didn’t do well on the hot Plaza far from the ocean. Also, while landscape fabric and mulch were cheap and provided a nice contrast, they aren’t the most “green” materials (red mulch is red because it is dyed red).  Alternatives are worth exploring.

This is probably the size limit of a Pop-Up Galaxy Garden.  It really required the entire crew and even then it was a tough job. Let’s hope the next garden is a more permanent installation!

Planning materials from this event can be accessed from Google Drive.

Many of the photos shown here were taken by Kathleen Schmitt; more photos of the event can be found on the PlayDay Gallery and San Diego Galaxy Gardens Flickr page.



  1. Sky1388 kasino

    Gardens of the Galaxy: Art of Science Learning Play Day!

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