What Goes Up, Must Come Down

The aboveground portion of the McMath-Pierce Solar Telescope at Kitt Peak National Observatory (KPNO), a Program of NSF’s NOIRLab, is seen here at sunset. The McMath-Pierce Solar Telescope, located about 88 kilometers (55 miles) from Tucson, Arizona, saw its first light in 1962. It continued operating for an impressive 55 years until being decommissioned in 2017. For much of its life, it was the largest solar telescope on Earth. The McMath-Pierce telescope was unusual in that it used a large flat mirror called a heliostat to track the Sun across the sky and continually send sunlight down into an underground tunnel where the telescope itself was located. This helped to minimize hot air currents in the light path of the telescope, which would degrade the quality of the image.

Though decommissioned, the McMath-Pierce Solar Telescope facility is being repurposed as the NOIRLab Windows on the Universe Center for Astronomy Outreach.