Telescope Green and other custom paint colors for a custom telescope

What color is a telescope? And what does it matter anyway?


Although old photographs in black and white might not be the most convincing evidence, at least this photo shows that the telescope paint was dark. Photo courtesy of Wesleyan University Special Collections & Archives.

Back in the day (AKA 100 years ago), the 20-inch Van Vleck telescope was painted black. I believe the rationale was that astronomers wished to keep the space in the dome as dark as possible; naturally a dark paint was in order. More scientifically, the color black absorbs light. Stray light in the dome is something to consider and painting a telescope so that it can absorb stray light to the maximum seems rather logical.

Today the telescope is painted white–or more specifically, a slight off-white. The rationale here is that white reflects light. Because white does not absorb light like the color black does, a white telescope will be cooler than a black one. This is important to regulate the temperature of the instrument. The mount however is still kept at a dark hue. As for why the dome itself is painted white outside, well the story is not too different.

Now for all you extreme telescope enthusiasts out there who want to know the specific paint colors, I’m talking color codes and more here, you are in for a fun story.

Paint can lid for Dark Dakota Shadow

Paint can lid for Dark Dakota Shadow with Benjamin Moore color codes. Photo by the author.

A while back, Bill Herbst, his wife, and a consultant from the Wesleyan Art Department decided on the colors to paint the telescope: Dakota Shadow for the mount and North Star for the tubes. The Dakota Shadow was a bit too light, so a request was put in for Dark Dakota Shadow with no white added.

Paint can lid for Telescope Green with Benjamin Moore color codes.

Paint can lid for Telescope Green with Benjamin Moore color codes. Photo by the author.

Over the summer however, while working on the telescope restoration, Fred received a mis-mixed batch of paint. To remediate the error, the Cromwell Paint Spot shop named a new paint color–with the proper mix of green, yellow, black, and white–for Fred and put it in their system as “Telescope Green.”

Matt and I called the Paint Spot to investigate further. We spoke to a very nice sales representative who looked up the paint color for us. He didn’t recognize “Telescope Green” off the top of his head, but when we gave him the custom code he found it immediately! The rep said that the shop still has Telescope Green paint in stock, but because it is a custom color, we would need to bring in the can with the lid and the code to actually get the paint.

Fred points out the coats of paint on the mount. Photo(s) by the author.

Fred points out the multiple coats of paint on the mount. (Photo by the author)

This was the look on Fred’s face when Avi suggested the paint color could be called “T-Tauri Taupe.” Fred said, “I know what taupe is and this isn’t anything close!”

This was the look on Fred’s face when Avi joked the paint color could be called “T-Tauri Taupe.” Fred said, “I know what taupe is and this isn’t anything close!” In any case, Avi was working on the telescope restoration with Fred over the summer and he’s the one who tipped me off about Telescope Green in the first place. Thanks Avi! (Photo by the author)

Avi laughing

And to round out this post, here is a picture of Avi laughing, maniacally probably (not). Could he be wearing a t-shirt in the tone of Telescope Green?? And will this become the trendiest new paint color?? Only time will tell…

How the Van Vleck Observatory reflects environmental conditions

Before Van Vleck was completed in 1916, Wesleyan’s “observatory” was a tower mounted on a dormitory, containing few instruments with little research capability. Prior to that, the university’s effort at a building devoted to astronomy was little more than a shed.

Professor John Monroe Van Vleck, who taught astronomy at Wesleyan for 50 years, believed the university could do better. He envisioned an observatory with the facilities necessary to make an impact on the world’s understanding of the universe. In 1903, Van Vleck’s family donated more than $25,000 to the university for a new observatory and planning began, but Professor Van Vleck passed away before he could see his vision come to life.

In his stead, Wesleyan’s president Stephen H. Olin entrusted Frederick Slocum, the new astronomy professor, with supervising the observatory’s design. Slocum began a detailed correspondence with Henry Bacon, the architect charged with designing the observatory, to recommend the location, design, and technology of the building. Slocum was as determined as Van Vleck had been to see the Wesleyan observatory contribute valuable research to the scientific community. He was aware that it would not be easy, as New England’s cold, wet, and changeable climate was not ideal for astronomical observation. Slocum used a number of means—geographical, architectural, and technological—to overcome the challenges of doing astronomy in the relatively poor observational environment of New England.

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Ivy league, no longer

In an earlier post, I traced the origins of the ivy that grew on the walls of the Van Vleck Observatory for much of its history. However, as you can see by comparing an early photograph of the observatory with the building today (below), the ivy has been removed. Why?


Van Vleck Observatory circa 1930 (in black and white), and today (color). Black and white image courtesy of Special Collections and Archives, Wesleyan University. Current photo by the author.

For decades, architects, scientists, and gardeners have been debating the desirability of allowing vines to grow on building walls.  Some considerations were primarily aesthetic:

“A home should seem to be tied to the ground in such a way that it will appear to rise from it without a sudden and abrupt breaking of the surface.”
N. H. Ellsworth, “Planting the Home Grounds: The Use of Vines,” House Beautiful, Volume 48, July 1920, 200.

“…nothing can be more unsightly than a good building metamorphosised with heavy growths of ivy or other plants.”
Sir Thomas Jackson for Times, quoted in “Creepers on Buildings,” The American Architect Volume 120, December 1921, 14.

But others concerned the material impact the vines had on the buildings.  According to a note in The American Architect and the Architectural Review of December 21, 1921 (below), even then, creeper plants were thought to be damaging to masonry.  (Agreement on this point is far from universal.  A 2010 study by Oxford University scientists concluded that ivy can act as a thermal shield and protect brickwork from intrusive moisture.)


“Creepers on Buildings,” The American Architect and the Architectural Review Volume 120, December 1921, p. 14. Image by Google Books.

From a closer look at the literature, it appears that the precise nature of the building material material determines whether a wall can sustain ivy without damage.  Some ivy plants apparently secrete an enzyme that erodes mortar of the kind found on historic buildings like the Van Vleck Observatory. According to Dave Hall, who maintained the grounds at Wesleyan University for over 30 years, much of the campus’s ivy was removed precisely because it was damaging the mortar.  It appears that the vines came down from the Van Vleck Observatory sometime in the late 1980s or early 1990s.

Incidentally, Wesleyan was not alone.  Many colleges such as Middlebury, Harvard and Yale carried out plans to strip ivy off historic buildings as early as 1982.  Ivy league, no longer!

Van Vleck’s living walls

As I was going over old photos of Van Vleck Observatory, I noticed that the now-bare walls of the building were at one point covered thickly in vines. What is more, it seemed that the presence of ivy was not simply an afterthought, or a decoration to make the building more “academic,” but an important design feature of the observatory itself.


Van Vleck Observatory, circa 1930. Image courtesy of Special Collections and Archives, Wesleyan University.

As the moniker “Ivy League” suggests, ivy has long been associated with college campuses. Planting a commemorative ivy vine at the base of an academic building has been a tradition of each graduating class at Princeton since 1866, and Smith College observes an annual “Ivy Day” at its commencement. Many Wesleyan buildings were formerly cloaked in ivy; the brownstone campus today looks much different than it once did.

But while the reasons for planting ivy may be partly traditional, at the Van Vleck Observatory, these vines were also grown for more practical purposes: to help moderate the temperature of the building itself. Ivy formed a living climate-control system, shading the brownstone exterior in summertime, and preventing the sorts of rapid fluctuations in temperature that might cause errors in measurement.

We can see how these considerations influenced the design of the building from the outset. Henry Bacon, most famous for designing the Lincoln Memorial in Washington, DC, was Wesleyan’s campus architect from 1913 to 1924. He designed Van Vleck with input from Frederick Slocum, the observatory’s first director. In a 1914 letter to Slocum, Bacon suggested the use of ivy to help regulate the temperature of the transit room, ensuring more accurate observations. In this sense, the building itself was a sensitive instrument, and ivy was one means of keeping it cool in the summer and warm in the winter.


A letter from Henry Bacon to Frederick Slocum dated July 23, 1914 in Box 2 of the Henry Bacon Collection. Image courtesy of Special Collections and Archives, Wesleyan University.

Of course, aesthetic considerations were also at play. Bacon’s suggestion was later met with agreement by a member of the Wesleyan faculty who thought ivy would make the observatory “a handsome building.” The faculty member’s delightful comment was quoted by Frederick Slocum in his address at the dedication of Van Vleck Observatory in 1916:

Little bits of plaster,
Little blocks of stone,
Make a handsome building,
When the ivy’s grown.