Science on Mount Hopkins

Mount Hopkins, Arizona, is an important site for astronomical research. We perform world-class scientific research at the Multiple Mirror Telescope Observatory, Fred Lawrence Whipple Observatory, and associated projects located high in the Santa Rita Mountains.

Research started in 1968. The site was selected for high elevation, dry weather, "good seeing" and dark sky.

Mount Hopkins continues to be an active, vital, site:

The Multiple Mirror Telescope is being converted to a 6.5-meter telescope, making it again one of the world's largest. ($20 million project)

The new 2MASS Survey Telescope began a survey of entire northern sky last year.

Project IOTA, an interferometer, has received funding to build a third telescope, thus completing its array.

The VERITAS project, a major new gamma ray observatory using an array of eight 10-meter-diameter reflectors, is in its initial phase. ($10-$15 million)

The Threat To Science

The value of this uncommon research site will be compromised by increasing sky brightness. Higher density zoning at the foot of the Observatory will not only bring many more residences, but will also attract commercial development with its bright light. Development of the Canoa Ranch at its present zoning density will be far easier for astronomy to co-exist with.

If zoning seeks to group compatible land uses together, and keep incompatible uses apart, then the zoning process should respect the environmental elements that create a rare and valuable research site and protect the environmental asset of dark skies.

What Is At Stake?

Since the early 1970s, local government has acknowledged, by regulation, the importance of dark skies. The Tucson/Pima County Outdoor Lighting Code, Ordinance No. 8210, recognizes the Observatory's sensitivity to light by defining Area A, the circular area, 25 miles in radius, the center of which is the center of Mount Hopkins Observatory, as the zone of greatest protection from outdoor lighting.

The Natural Resources of southern Arizona mountaintops — Mount Hopkins, Kitt Peak, Mount Lemmon/Mount Bigelow, and Mount Graham — have made it an astronomy capital.

Observatories and their support industries provide clean, high-tech, well-paid jobs. Business Week calls Tucson "Optics Valley" because of the number of optical products businesses _ most of which are astronomy spin-offs.

$$$ The U.S. government, individual states, and foreign countries collectively have invested hundreds of millions of taxpayer's dollars in developing the various Arizona observatory sites. About $200 million of these dollars have been spent for facilities at the Observatories on Mount Hopkins.

It seems only wise to protect such a vast investment.

Impact Of Residential Lighting On Sky Brightness

The artificial light of sky glow overwhelms the fainter natural light of stars and galaxies, making them harder _ and in the extreme case — impossible to study.

How does the sky glow from 6,000 houses built in Canoa Ranch compare with houses built in Tucson?

6,000 houses at Canoa Ranch = 180,000 in Tucson

Why Is That?

Distance from Mt. Hopkins to Canoa Ranch = 9.5 miles

Distance from Mt. Hopkins to Tucson = 37 miles

(Broadway & Alvernon)

One house at the distance of Canoa Ranch has the effect of 30 houses at the distance of Tucson. (See calculations below.)

How Does That Compare With Sky Glow From Existing Zoning?

Calculated skyglow from existing zoning of 6,000 acres

with 1 home per 4.3 acres = 1,395 Canoa Ranch houses = 41,850 Tucson houses

The Fairfield proposal for 6,400 houses

is 4.3 times as many houses = 180,000 Tucson houses

The Numbers

Using the formula* I = population


I = Increase in sky glow

N = equivalent number of houses in Tucson

N = 6,000 houses in Canoa Ranch

37 2.5 9.5 2.5

N = 6,000 * (37/9.5)2.5

N = 6,000 * 30 = 180,000

* ("Walker's Law," from International Dark-Sky Association

Information Sheet 11)

Partners in Science

Fred Lawrence Whipple Observatory

Smithsonian Institution

Harvard-Smithsonian Center for Astrophysics

Multiple Mirror Telescope Observatory

Smithsonian Institution

University of Arizona

Whipple Gamma-Ray Observatory

Harvard-Smithsonian Center for Astrophysics

Purdue University

Iowa State University

University College, Dublin

University of Leeds, England

The Whipple Gamma Ray Observatory is funded by the U.S. Department of Energy, the Smithsonian Institution, and NASA.


Harvard-Smithsonian Center for Astrophysics

Purdue University

Iowa State University

University College, Dublin

University of Leeds, England

University of Chicago

Northwestern University

Boston University

University of Utah

Washington University, St. Louis

Two Micron All Sky Survey (2MASS)

University of Massachusetts, Amherst

Jet Propulsion Laboratory/Caltech (IPAC)


National Science Foundation

National Optical Astronomy Observatories

Smithsonian Institution

U.S. Navy

Project IOTA

Smithsonian Astrophysical Observatory

Harvard University

University of Massachusetts

The Telescopes

Fred Lawrence Whipple Observatory

1.5-meter Tillinghast Reflector for spectroscopy of stars & galaxies.

1.2-meter reflector for visible and infrared imaging and photometry.

Multiple Mirror Telescope Observatory

A 4.5-meter becoming a 6.5-meter MMT. First of the new generation of large telescopes, the MMT was the first electronic telescope in the world and first to combine the light from (6) smaller telescopes as one instrument. Now it is undergoing a conversion to a single 6.5-meter-diameter mirror which will make it the largest single-mirror telescope in North America.

Whipple Gamma-Ray Observatory

10-meter-diameter optical reflector for studies of gamma rays.


Proposed array of eight 10-meter-diameter reflectors for gamma ray studies.

Two Micron All Sky Survey (2MASS)

A 1.3-meter telescope dedicated to canvassing the entire sky for stars and galaxies as much as 50,000 times fainter than the stars seen in the last such infrared survey more than 25 years ago.

Project IOTA

Two 45-centimeter telescopes working together to make high resolution measurements such as determining star diameters.

Your participation in local government is important.

If you wish to make you opinion known on any aspect of the Canoa Ranch Specific Plan rezoning, write to the Pima County Board of Supervisors.

A letter carries the most impact. A phone call or fax, however, is better than nothing.

The next public hearing is scheduled for January 12, 1999, 4:30 p.m., at the Sahuarita High School Auditorium.

Mr. Mike Boyd, Chair

Pima County Supervisor, District 1

130 W. Congress St., 11th Floor

Tucson, AZ 85701 Tel: 740-8126 Fax: 740-8489

Ms. Sharon Bronson

Pima County Supervisor, District 3

130 W. Congress St., 11th Floor

Tucson, AZ 85701 Tel: 740-8051

Mr. Ray Carroll

Pima County Supervisor, District 4

130 W. Congress St., 11th Floor

Tucson, AZ 85701 Tel: 740-8094 Fax: 740-2721

Mr. Dan Eckstrom

Pima County Supervisor, District 2

130 W. Congress St., 11th Floor

Tucson, AZ 85701 Tel: 740-8126

Mr. Raul M. Grijalva

Pima County Supervisor, District 5

130 W. Congress St.,11th Floor

Tucson, AZ 85701 Tel: 740-8126

In Summary

The Observatory does not oppose building in the area, generally speaking, and could tolerate the light resulting from construction on the Canoa Ranch property as it is currently zoned.

The tremendous increase in population density allowed for under the rezoning proposal would result in a significant increase in sky brightness and directly affect the quality of the Observatory site. The approximately new 15,000 residents on the rezoned Canoa Ranch would attract rapid and dense development of the commercial acreage as well. The commercial property, sports lighting, and resort hotels that would be allowed under the rezoning are all great generators of light.

The Observatories on Mount Hopkins have been conducting world-class research since 1968. First-rate dark sky observing sites are rare and worthy of protection. Houses can be built anywhere, Observatories cannot.

Whipple Obs., 11/98