Standing 100’ high on the south-east ridge of Kitt Peak National Observatory (KPNO) is the McMath-Pierce Solar Telescope. Construction started in 1959, and once completed in 1962, it was the largest solar telescope in the world, a title it held until January 2020 when the Daniel K. Inouye Solar Telescope (DKIST) located on the island of Maui, Hawaii saw first light. While McMath-Pierce may no longer be the largest solar telescope, the number of first discoveries and its involvement in the Apollo Lunar projects still makes it the most exciting and accessible of the telescopes at KPNO.
As a docent leading daytime telescope tours at KPNO, I have to say that the McMath-Pierce Solar Telescope tour is my favorite. The sheer size of the telescope, of which only one-third is visible above ground, gives visitors the opportunity to stand inside the reflection tunnel. Going into the control center is like stepping back in time. Much of the original computers, and other equipment used to make observations are still present. And the fact that the solar telescope was used to help Apollo astronauts view areas of the moon suitable for landing shows the versatility of the telescope with regards to the diverse projects for which the telescope was and is still used.
After the initial introduction which explains safety protocols, and general history of KPNO, the visitors begin a quarter-mile walk to the telescope. The top portion of the telescope is visible from the visitor center. About half-way there, the telescope begins to loom large. Visitors are able to see what appears to be a right triangle. To the north stands a tower 100’ tall with 3 flat mirrors (heliostats) sitting on top. From the tower extending 200’ towards the south is the reflection tunnel. Actually, 200’ is what is visible above ground. The tunnel extends another 300’ below. It’s at this point where the tunnel meets the ground that visitors can stand inside a public observation area within the tunnel.
As they look to their right and up, they can see the 3 heliostat mirrors located atop the 100’ pillar. Then, I challenge them to look left down the tunnel to see if they can spot the primary mirror at the bottom. No, you won’t be able to see it. However, you are able to see more mirrors which redirects the light reflection down into the control center. And yes, you are allowed to take plenty of pictures from behind the safety glass.
Once visitors are in the lobby of the structure, they get to see photos of the construction of the telescope, and the astronomers for whom the telescope is named. There is a guest book where you can see the signatures of the many Apollo astronauts who visited the control room to make observations of Earth’s moon in preparation for those historic flights. Visitors will walk down a long hall filled with scientific information regarding Earth’s star which we call Sun. Past that is the actual control room where researchers from around the world and astronauts stood around 1 of 3 platforms to conduct their experiments and making their observations.
You may remember that I have mentioned 3 mirrors. And now, I am mentioning 3 observation areas. You see, The McMath-Pierce Solar Telescope is actually 3 telescopes in 1. Each of the heliostats and its respective mirrors can be used independently. So in theory, three separate observing projects could have been conducted at the same time. Typically one project was conducted using the main heliostat and the large instrument bench in the middle of the control room. But the auxiliary heliostats were used as well.
It’s around this main platform that the astronauts stood. With the reflection of the moon projected onto the platform, all of the astronauts could easily view the surface of the moon together. It made it easy for them to point to the same areas to determine the best place to land.
Today, visitors can stand at the various platforms, get a glimpse of the top of the spectrograph, and feel like they are on the set of a 1960s sci-fi movie. The reel-to-reel tape computers, and big flashing lights where high tech back then, you know.
On special occasions, the public can come observe special events such as the 2019 Mercury transit of Sun. Technically, the National Science Foundation is no longer inventing in McMath-Pierce research projects. Instead the Kitt Peak Visitor Center has received a grant to update the telescope into the Windows on the Universe Outreach Center. Sometime in 2021, visitors will be able to attend planetarium shows, enjoy state-of-the-art exhibits, learn about the cosmos with the 3-D Sphere, and so much more.
I hope you have enjoyed this very brief overview of my tour. You, too, can tour this fascinating structure and take a walk back in time to learn about the amazing discoveries and fascinating history of this iconic telescope. Tours of the McMath-Pierce normally start at 10:00 A.M. daily at the Kitt Peak Visitor Center https://visitkittpeak.org/daytime/
Antoinette Freeman, Kitt Peak Docent.