The Kitt Peak Virtual Tour



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The McMath-Pierce Solar Telescope is the largest solar instrument in the world.

This is also the world's largest unobstructed aperture optical telescope, with a diameter of 1.6 meters.

Dedicated as the McMath Solar Telescope on November 2, 1962, the facility was later renamed to honor Dr. Keith Pierce as well as Dr. Robert McMath.

The structure includes a tower nearly 100 feet in height from which a shaft slants two hundred feet to the ground. The shaft continues into the mountain, forming an underground tunnel where the sun is viewed at the prime focus. An aerial shot of the top of the McMath-Pierce telescope reveals the 3-mirror heliostat which collects light and directs it down the tunnel. Unlike other solar telescopes, the McMath-Pierce is sensitive enough to observe bright stars in the night.

Permanent instruments include a dual grating spectrograph capable of extended wavelength coverage (0.3-12 microns), a 1-meter Fourier Transform Spectrometer for both solar and laboratory analysis, and a high-dispersion stellar spectrometer.

The McMath-Pierce is used to study the structure of sunspots, as well as sunspot spectra. A sunspot is a temporary cool region in the sun's photosphere. A typical sunspot appears dark and irregularly shaped.

This image of a sunspot with exceptional detail was taken on September 9, 1990, with the McMath-Pierce Solar Telescope.The outer diameter of this sun spot measures about 14 thousand miles. Suspended over the umbra, the sunspot's darker inner core, is a rope-like light bridge.

Important discoveries revealed with this telescope include: a detection of water and isotopic helium in the sun; solar emission lines at 12 microns; first measurement of Kilogauss magnetic fields outside sunspots and the very weak intra-network fields; first high resolution images at 1.6 and 10 microns; detection of a natural maser in the Martian atmosphere.

Data archives from the solar telescope are available on the World Wide Web.

The McMath-Pierce Facility is part of the National Solar Observatory, one division of the National Optical Astronomy Observatories (NOAO).


This facility has three telescopes in one: the main, east auxiliary, and west auxiliary mirror systems. The three can be used concurrently or independently.

Include a stop at the McMath-Pierce viewing gallery to look inside the underground tunnel when you visit Kitt Peak.



The sun has about the same apparent size in the sky as the moon. In reality, the sun has a diameter about 400 times greater than that of the moon, but it is about 400 times farther away. This coincidence results in the moon appearing to cover the sun on some occasions, producing a solar eclipse.


When are we closest to the sun?

And that month is...


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NOAO is operated by the Association of Universities for Research in Astronomy (AURA), Inc. under cooperative agreement with the National Science Foundation. The Kitt Peak Virtual Tour is developed and maintained by the NOAO Educational Outreach Office.

Copyright © 1999 The Association of Universities for Research in Astronomy, Inc. All Rights Reserved.