“Telescopes play with rainbows,” says volunteer Bill Wren to a dimly lit room packed with visitors of Sunspot Solar Observatory. The crowd is comprised of both young and old tourists who’ve flocked to the Observatory to tour one of the world’s greatest solar telescopes, the Richard B. Dunn Solar Telescope (DST), operated by New Mexico State University. Their eyes remain fixed on the slide show Wren has put together to illuminate the information he shares about the telescope, the Sun, and our long plight to fully understand its marvels.
Wren flips through screens depicting explosive coronal mass ejections, hot gas brimming on the Sun’s atmosphere, light spectrums, and the immensity of the Sun compared to the planets which orbit it, including ours. “It’s incredible, folks,” Wren says, explaining the connection between ancient solar science and modern technological innovations, like the DST.
Wren, who is recently retired from McDonald Telescope in Texas, worked a long career as a public information specialist—and eventually as special assistant to the superintendent—for over thirty years. He was responsible for leading educational outreach programs at the observatory, but his career offered him many other exciting opportunities, including working alongside astronomers, studying distant celestial objects, building telescopes, and promoting the value of dark skies to oil and gas companies. Even now, in his retirement, Wren finds himself drawn to supporting public education efforts, which is why he reached out to Sunspot Solar Observatory after moving to Cloudcroft, NM in 2021.
“I just wondered if they could use somebody to do programs, because that’s what I really enjoy doing,” says Wren. “I was an academic tutor for astronomy, and I just enjoy teaching people about astronomy, because I find it so fascinating. Happily, [the people at Sunspot] said sure! They basically gave me the freedom to do it how I wanted to do it, so I do what I learned when I was at McDonald. I prime [the visitors] to see the telescope, help to facilitate the tour, and then I do the spectroscopy demonstration.”
During Wren’s presentation, visitors learn about the physics of the Sun, a brief history of astronomy, and the unique history and features of the Dunn Solar Telescope—which Wren educated himself on before beginning his program. Initially, the presentation was around half an hour but as Wren continues to expand his own knowledge on DST, he fills the presentation with more exciting content, simulations of solar events, and photos captured by the DST to share with visitors.
“The Dunn Solar Telescope is just really amazing,” says Wren. “It’s such a neat telescope. I feel very fortunate to be able to show people around there. And trying to explain how spectroscopy works there is great.”
Originally called the Vacuum Tower Telescope (VTT), the Dunn Solar Telescope is regarded as one of the best solar facilities in the world. Using its vacuum tube light path, the telescope essentially “smears sunlight out into its constituent colors and onto the optical bench,” says Wren, “which allows astronomers to use a variety of instruments to study sunlight.”
It was renamed in the 1990s to honor astronomer Richard B. Dunn, who helped determine some of the defining features of the telescope, including its rotating floor, which helps the telescope rotate as the sun rotates. As Wren says, “If [the telescope] didn’t rotate, the image would slowly turn and blur. By rotating the telescope, you de-rotate the image of the Sun.” During the tour, visitors can witness the floor moving if they give it a push with their feet; however, it doesn’t move rapidly like a carnival ride. Rather, it rotates so subtly that a scientist spending the day observing wouldn’t necessarily feel like they were moving.
For the last year, Wren has spent his free time spreading this knowledge with tourists. He conducts the programming at Sunspot Solar Observatory on the first Saturday and Sunday of every month, helping to facilitate a tour of the DST facility as well as performing a spectroscopy demonstration, which is an area of astrophysics that has always amazed him.
“If you look at the history of astronomy, that’s when it really became astrophysics—when you could use spectroscopy to actually decipher the chemistry and the physics going on at the source of your observation,” he explains. In his presentation, Wren recounts how the spectrum of rainbows revealed to scientists Gustav Kirchhoff and Robert Bunsen (of the Bunsen burner) helped scientists narrow down what elements were present in the sun’s atmosphere and how those revelations led to a groundbreaking conclusion: the Sun is a star.
Some astronomers never fathomed that we could understand as much about the properties of stars or the Sun as we do now, including one philosopher referenced in Wren’s presentation. A quote from August Comte, highlights the commonly held belief that by the mid-1800s, the limits of astronomy had been reached. Now we know just how far from the truth this is.
Wren likes to share this kind of knowledge with others to express how amazing it is that we have come so far with the technology needed to study the Sun, stars, and distant celestial objects. “What Comte said was a common belief,” Wren says. “They wanted to know what was going on, what was happening in the stars, what they were made out of. They just lacked the means to decipher and discern it, so they believed they’d reached the limit of what they could understand. That is, until spectroscopy came along and revolutionized things.”
Spectroscopy—the study of light according to color—is an area of astronomy that Wren has been exploring and demonstrating to the public for years. In his program at Sunspot Solar Observatory, he likes to incorporate this intriguing and beautiful piece of science as a way to give visitors a hands-on experience.
“One of the programs I developed while working at McDonald was a spectroscopy demonstration using handheld diffraction gratings that show the emission lines for different chemical elements,” Wren says. “Being able to show people that you can identify different chemical elements from a distance because they emit and absorb light at particular colors is quite rewarding. When people wonder ‘how do you know what it’s made out of or how hot it is,’ the answer to all those questions is in the technique of spectroscopy.”
Inside the Dunn Solar Telescope facility, the group of visitors gather in the dark to participate in their own spectroscopy experiment. Using tubes of different chemical elements like mercury, hydrogen, and neon, Wren shows how each element gives off their own unique color patterns on the spectrum. Looking through special lenses called transmission gratings, visitors can see for themselves the varying wavelengths, visualizing how astronomers are able to decipher what chemical compound makes up an object they are viewing from lightyears away. This is one of the reasons Wren finds that combining the history of astronomy with a spectroscopy demonstration is so vital to the public’s understanding of astrophysics.
“The history of it lays the factual groundwork,” he says. “The key to it, as is the case with so many things, is to be able to see it with your own eyes. That is what makes all science valid. It can be recognized as fact and as truth, because anybody can perform the same experiment and come up with the same results with the proper equipment. You don’t have to take my word for it. You can see it for yourself.”
While gazing at the rainbows depicted through their special lenses, visitors become part of the experiment. They are participating in the same observation that has been performed by scientists for decades, connecting with them as much as they are with the marvels of the universe. It is this connection which Wren hopes will inspire everyone as they leave the observatory and return to their lives.
“I often hear that looking through a telescope makes someone feel so small, you know? Like, they’re just this tiny little spec in the corner of this vast universe. And while that may be true, and I understand the feeling, there is also this sense of being connected, that you’re participating in this scheme of things. I mean, that’s kind of what cosmos means. Translated, I think it’s intelligence,but it’s basically the structure or scheme of how things work the same. It’s what astronomers call the cosmological principle: that the same laws of chemistry and physics we see at work on the surface of the Earth apply throughout the universe, given the conditions of temperature and pressure and density and all that stuff.”
Once the tour ends, visitors are free to roam the grounds, explore the other solar facilities—which have been decommissioned in recent years—walk the trails, and check out the gift shop and museum. Wren hopes to continue spreading a love of astronomy in others through his work with Sunspot and other observatories in the southwest. He believes the work astronomers do helps people understand their place in the cosmos. “I strongly believe in emphasizing the difference of ‘having been placed into the universe’ and ‘being a product or participant in the larger universe’,” says Wren. “It helps provide me with a sense of connectedness. It’s a kind of mystical thing.’”
NMSU graduate student Anna Snider’s project on the Richard B. Dunn Solar Telescope was funded by NSF grant 31076.
The full article can be seen at https://newsroom.nmsu.edu/news/dunn-solar-telescope-tours-give-visitors-a-colorful-experience/s/88706143-e16e-4aac-a33f-0b4c18a24751