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A spirit of place where the modern universe was born.

Want to make contact with places where today's cosmos took shape? Here's our guide.

HISTORICAL TELESCOPES AND ASTRONOMICAL sites are portals to the universe and to our past. They unite us as a species in the face of an immense and virtually fathomless existence. But they also remind us of the challenges we have faced learning about the universe we have come to know today.

As I planned out the suite of artifacts for the new "Explore the Universe" gallery at the Smithsonian Institution's National Air and Space Museum in Washington, DC, I wanted to recreate the emotional and sensual experience of observing new universes using new tools. The exercise forced me to ask again and again: Who were the people who discovered new universes, and where are the tools they built and used?

What, if anything, is left of Tycho's Stjerneborg on the island of Hven? Of Galileo's telescopes? Of William Herschel's 20-foot reflector, the one he believed could penetrate beyond the limits of our stellar realm? Can one examine the telescope Edwin Hubble used at Mount Wilson to discover the true limits of our galaxy and the realm of the galaxies beyond? Where was the expansion of the universe first detected, if not comprehended? And can one visit the horn-shaped radio antenna that Arno Penzias and Robert Wilson used to first hear the birth cries of our expanding universe?

Questions like these prompted me and my colleagues to design dioramas that would provoke what museum people sometimes call a "spirit of place." Of course, we knew that no museum could expect to fully capture the spirit of a place where pivotal discoveries were made. To do that, one must travel.

Places like Britain's Stonehenge and Jai Singh's observatories in India--along with many other fascinating archeological sites that dot the ruins of most civilizations --are powerful reminders of the antiquity of astronomy. Each deserves to be seen, but here we will talk only about modern places, places where the classical Earth-centered cosmology was overturned again and again.


A pilgrimage to the sites where our modern physical universe was discovered in stages really should begin with Tycho Brahe's observatories on the island of Hven (sometimes written Ven) and in the castles of Prague. Hven is at the northern end of the narrow Ore Sund separating Sweden and Denmark, about 24 kilometers (15 miles) from Copenhagen and 6 km from the Swedish town of Landskrona. It was on the island of Hven that Tycho and his assistants first collected evidence that called into question the dominant Aristotelian cosmology and eventually enabled Johannes Kepler to show that planets travel in elliptical orbits around the Sun.

Sadly, nothing remains of Tycho's incomparable 16th-century castle, Uraniborg, though a beautifully reconstructed Renaissance garden aims to partially replicate its original grounds on Hven. Stjerneborg--Tycho's partially subterranean collection of observing chambers, the state of the art in the late 16th century for measuring the positions of the Sun, Moon, planets, and stars --was excavated around 1950, and some of its original walls and instrument foundations now are visible. These have been covered with replicas of the aboveground structures, built to function as a small museum, and multimedia presentations are given there to evoke a night of observing during the facility's heyday.

One can visit Tycho's grave in Prague. A beautiful 210-centimeter (7-foot) wood-and-brass quadrant built for Tycho's observatory is on display at the Boerhaave Museum in Leiden (the Netherlands), and a faithful full-scale replica of his great Equatorial Armillary Sphere--a precise sighting device for measuring the positions of celestial objects--is part of our gallery exhibition in Washington.

Remains of Galileo Galilei's telescopes, and, indeed, much of his scientific legacy, are artfully housed in the Museum of the History of Science (Istituto e Museo di Storia della Scienza) in Florence, Italy, just to the east of the landmark Ponte Vecchio. Pay a small entrance fee and search out Rooms IV and V, where you will find not just Galileo-period telescopes and a fascinating array of more modern astronomical instrumentation; you will see the equipment most likely to have been made and used by Galileo himself--two complete telescopes and an elaborately mounted objective lens. (The latter is quite likely the one Galileo used to discover the four largest Jovian moons and then to plot their motions, demonstrating that there are centers of motion in the heavens other than Earth.)

On an even more personal plane, you can commune with the remains of one of the master's middle fingers, nicely preserved along with his lodestones, his portraits, and models of his clock pendula and inclined planes. You also can examine a facsimile of Galileo's 1610 Sidereus Nuncius (Starry Messenger), wherein he announced many of the discoveries that confirmed the Copernican model of the cosmos.

Many science centers display Galilean-type telescopes for viewing. By giving visitors a chance to seek the simulated Moon with a replica, our Smithsonian exhibition demonstrates just how crude Galileo's telescopes really were.

William Herschel's home in Bath, England, is a museum and astronomical shrine. William and his sister Caroline lived at 19 New King Street, a distinctive Georgian building that has been restored to depict commoner household life in the 18th century. It was here, in 1781, that William discovered a new planet, now known as Uranus--a feat that propelled him into a career as "King's Astronomer."

William and Caroline Herschel eventually moved from Bath to Datchet and then finally to Slough, near Windsor Castle. There they served King George and could "mind the heavens," as Caroline--herself the discoverer of 8 comets and 13 deep-sky objects (S&T: November 2002, page 107)--later would record in her memoirs.

In these latter places, William built huge reflecting telescopes with speculum-metal mirrors to increase his "power of penetrating into space." And it was in Slough --mainly with his "large" 20-foot* reflector--that he mapped out the limits of the sidereal universe and pondered the nature of the enigmatic nebulae. These passions laid the groundwork for Hubble's eventual discovery of our galaxy and of a universe of galaxies--arguably making William Herschel the grandfather of modern observational cosmology.

The Bath Museum preserves William Herschel's basement workshop and contains a replica of the 7-foot reflector he used to discover Uranus, as well as original speculum-metal mirrors, models, and memorabilia. By the good graces of the National Maritime Museum, London, Herschel's "large" 20-foot telescope tube (complete with an 1812-inch mirror) is on loan to the National Air and Space Museum, where, in a simulated garden setting, it models a December 1791 observing session. The Adler Planetarium and Astronomy Museum in Chicago exhibits an original Herschel tube and mirror of the size and type used to discover Uranus. That telescope sits in a reconstructed mounting.


Mount Wilson is a wonderful half-day road trip from downtown Los Angeles. The ascent into the precipitous San Gabriel Mountains is spectacular, and the last stretch, while mildly harrowing, is safe enough if you drive slowly and avoid falling rocks and earthquakes. One usually parks in a large lot just behind an open-air (but covered) picnic area. From the parking lot, signs direct you to the observatory.

The best place to start, though, is the small historic museum, which displays photographs taken by the telescopes and provides a roster of current events. The museum has been modernized and is wheelchair accessible (though the bathrooms are not), and there is a robust group of knowledgeable volunteers, members of the Mount Wilson Observatory Association, eager to educate and entertain the public with lectures, walking tours, and occasional stargazing sessions. On special occasions and by reservation, visitors can actually tour the 60-inch-telescope chambers, and the telescope can be rented for a night of observing.

Two of the most active research programs at Mount Wilson today are interferometry (May issue, page 30) and adaptive optics (S&T: October 2001, page 30)--techniques that can reveal very fine structure in astronomical objects. Mount Wilson actually is the birthplace of optical stellar interferometry, in which light received at two or more locations is mixed in order to generate interference patterns. The diameters of red-giant stars were first measured with this technique in the 1920s by Albert A. Michelson.

The 100-inch Hooker reflector is the telescope that Edwin Hubble used in the 1920s to determine the distances to galaxies, showing for the first time that they lie far beyond our Milky Way and are "island universes" in their own right. This also is the telescope Hubble used to calibrate an enigmatic property of "spiral nebulae" (as spiral galaxies then were called).

Vesto M. Slipher had discovered at Lowell Observatory that spirals speed through space at velocities far, far greater than do stars in our own galaxy. Astronomers were searching for some organizing principle that could explain these huge speeds (one million kilometers per hour or more in some cases). Hubble finally found one in 1929, when he discovered that the distances to galaxies (his specialty) were proportional to the galaxies' speeds, which Slipher and others had determined using spectrographs. Distant galaxies all were receding from us faster than were closer ones. This did not mean that we were at the center of an expanding universe. Rather, this meant that the universe everywhere was expanding (October issue, page 30).

Looking at this great telescope back in the 1950s through a portal in the visitor's gallery, I held my breath, thinking, "This is where the modern universe was discovered." Today the National Air and Space Museum proudly displays the Newtonian Mirror Cage from the 100-inch Hooker reflector. Happily, the telescope itself is still in active use.

As the above account suggests, the radial (line-of-sight) velocities of galaxies are critical to our modern picture of the cosmos. Slipher was the first to measure them, just before World War I. He found that the absorption lines of identifiable chemical elements that are seen in the spectra of fuzzy spiral "nebulae" are substantially shifted from their positions in a laboratory spectroscope, in most cases toward longer (redder) wavelengths. The degree to which a galaxy's spectral lines are shifted indicates its radial velocity.

Today, many observatories routinely measure the radial velocities of faint galaxies (February issue, page 32). But a century ago there were very few places capable of doing so. Slipher optimized his spectrograph using a design closely based upon that of the first fully successful photographic spectrograph, built for William Wallace Campbell at Lick Observatory in the 1890s.

Nestled within direct view of populous San Jose, California, Lick Observatory is not only the birthplace of precision photographic spectroscopy, which enabled the radial velocities of stars, galaxies, and nebulae to be measured accurately for the first time; it also was the world's first permanent major mountaintop observatory.

Getting to Lick requires a bit of spirit: access from San Jose, at the upper end of Alum Rock Avenue, is by a winding, narrow road that is reported to have 365 turns with names like "Rim of the World." At the end of this road the great dome of Lick's 36-inch refractor beckons on a parapet of naked crushed rock. Park in front of the building for a magnificent view of San Francisco Bay.

A limited number of special viewing sessions with Lick's 36-inch refractor (for a decade the world's largest) and 40-inch Nickel reflector are available through an active program that includes concerts and lectures on cutting-edge astronomy topics. You have to book ahead to gain a ticket. But you can drive up to the observatory almost any day of the year for short informal talks in the 36-inch dome.

In addition to its historic 36-inch refractor, which Edward Emerson Barnard used to discover Jupiter's moon Amalthea, Lick's 120-inch Shane reflector (housed separately) also is available for inspection. It is the primary instrument that R. Paul Butler (Carnegie Institution of Washington), Geoffrey Marcy (University of California, Berkeley), and their colleagues have used to discover dozens of extrasolar planetary systems.

Lowell Observatory has a wonderful and varied public program. Only a few minutes' drive from the business district of Flagstaff, Arizona, nestled among tall, aromatic Ponderosa pines, the observatory's Mars Hill campus is both refreshing and exhilarating. Lowell's Rotunda Library (open to the public) exhibits historical instruments, including the aforementioned spectrograph that Slipher used on the observatory's famous 24-inch refractor to first detect the large velocities of spiral nebulae. (Campbell's spectrograph, the granddaddy of all such precision radial-velocity devices, is on display in our exhibit at the Smithsonian.)

There are regular tours of Lowell's famous 24-inch refractor, the one Percival Lowell, the observatory's namesake and founder, used to draw all those canals on Mars (June issue, page 28). It is still magnificent in its marvelously quirky, truncated conical wooden dome. Footpath signs lead to other sights, such as the lovely little astrograph that took the plates Clyde Tombaugh used to hunt for Pluto in 1930. And to be sure, as with a growing number of our greatest observatories sensitive to public outreach, there is a terrific modern visitor's center filled with neat stuff relating to the history of planetary and stellar astronomy as well as the Lowell legacy.

Fully two kilometers above sea level, Flagstaff is a virtual city of observatories. Ohio State University moved its venerable Perkins 69-inch reflector to the area in the 1960s, adding a new 72-inch mirror a few years later. This is one of the telescopes that Vera Rubin used in the late 1960s, when she first plotted out the rotation curve of M31 and realized that there had to be an enormous amount of unseen material causing the galaxy to rotate like a phonograph record. She had detected what we today call "dark matter," the identification of which may well be the next revolution in our understanding of the universe. The Perkins 72-inch telescope can be seen during private tours of the astronomical facilities on Anderson Mesa, a 12-mile (19-km) drive from downtown Flagstaff, as can the cutting-edge Naval Prototype Optical Interferometer.


If the techniques used to discover the expanding universe were developed at Lick, first applied at Lowell, and then spectacularly confirmed at Mount Wilson, it was only on California's Palomar Mountain in the 1950s that the value of the universe's expansion rate--the Hubble constant--was honed down to a range that fit reasonably well with the ages of the Earth, the Sun, and the stars.

The 200-inch George Ellery Hale reflector at Palomar was at the optical leading edge throughout the mid-20th century, and it is the instrument that first enabled astronomers to discover that quasi-stellar radio sources, or quasars, recede at enormous velocities. The implications--that quasars are billions of light-years from Earth, and that they are vastly more luminous even than large galaxies like the Milky Way--were revolutionary, and astronomers still are trying to work out exactly how quasars shine.

With a superfast photographic spectrograph at its f/3.3 prime focus, the Hale 200-inch was for a quarter century the world's largest telescope. Once the reflector was completed in 1948, Palomar was the place to go to peer to the ends of the universe as it then was known. Now the Hale telescope is fitted out with vastly improved electronic detectors (many sensitive to infrared light), and the old prime-focus spectrograph is on display at the Smithsonian.

There is a little museum at Palomar, and a small viewing gallery at the foot of the 200-inch dome allows astronomical pilgrims to peer at the unfathomably huge Hale telescope. On my last visit, just a few years back, the little museum had some interesting bits and pieces of Palomar history, but it didn't explain the observatory's continuing relevance in the age of truly revolutionary 8- and 10-meter reflectors. Scott Kardel, Palomar's new outreach coordinator, promises a makeover in the near future.

If the universe really is expanding, most astronomers infer that it must have evolved from some denser state in the past. The newborn universe, it therefore follows, was a very hot place. As a result, physicists predicted long ago that the redshifted glow of the original cataclysm should still be detectable in the microwave region of the electromagnetic spectrum.

The prediction was confirmed in 1965 by two astronomers working at the Radio Research Laboratory of Bell Laboratories (now part of Lucent Technologies) in Holmdel, New Jersey. Arno Penzias and Robert Wilson were struggling with a large and very sensitive radio receiver they wanted to use for radio astronomy. But they could not clear the system of all unwanted static, even after they removed the pigeons that were depositing white dielectric substances in the instrument's horn-shaped antenna.

A few phone calls to physicists in nearby Princeton, however, made Penzias and Wilson realize that they were fighting with the birth cries of the universe--the remnant fireball of the Big Bang. Princeton physicist Robert Dicke and his students actually were looking for the same relic radiation, but with a far smaller antenna. Once they heard from Penzias and Wilson, they made some adjustments and found it too.

An official landmark in the eyes of the US National Park Service, the great Holmdel horn still sits on quiet Crawford Hill, just off the Garden State Parkway; but the electronics that Penzias and Wilson used to make their epochal discovery are on display in Germany's Deutsches Museum in Munich. The pigeon trap the Nobel Prize winners used to rid the horn of organic noise takes pride of place in our Smithsonian exhibition, along with a replica of the original chart-recorder tracing that revealed the cosmic microwave background radiation.


The hot Big Bang model for the universe's origins that Penzias, Wilson, and Dicke's team so spectacularly confirmed has been scrutinized by instruments ranging from huge optical telescopes on mountaintops to vast radio-antenna arrays in desolate valleys and sensitive radiometers carried all over the world and beyond.

Of prime importance is the Cosmic Background Explorer, or COBE, spacecraft, which mapped the cosmic microwave background radiation, showing the first evidence of structure in the 380,000-year-old fireball. COBE was followed by a couple dozen ground-based and balloon-borne infrared and microwave "telescopes" that refined its view, yielding physical evidence that the universe expanded especially rapidly in its infancy (S&T: July 2000, page 24).

Sharing the experience of discovery by actually seeing the sites and tools is rather different in the modern era of electronic astronomy. COBE is in space, its control room at NASA's Goddard Space Flight Center no longer is accessible to the public, and most of today's ground-based or suborbital microwave-mapping instruments operate from remote locations like the South Pole and 5,000-meter-high mountain valleys. (That said, many of the optical and radio telescopes that have made astronomical history are accessible to the public to varying degrees, and they are terrific scene-grabbers on the isolated mountaintops of Arizona and New Mexico, the strato-volcanoes of Mauna Kea in Hawaii, and in the mile-high foothills of the Chilean Andes.)

We historians and curators do our best to collect astronomical instruments when they are no longer used and display them in museums and science centers. But the best way to really appreciate how telescopes and other astronomical devices now are used is to visit any modern observatory or astronomy department, where most of the work is done in front of a computer terminal.

In fact, the observing experience using modern ground and space-based instruments feels not unlike a standard office setting, with a few more monitors and gadgets floating around and focused people tweaking them to make them work right. The observer sits at a console and remotely operates the telescope, which can be in an adjacent chamber, across the country, or in orbit. This fact of life has utterly changed the observing experience, greatly freeing up the astronomer to manage the affairs of both research and daily life.

But as today's instruments become tomorrow's relics, this fact of life is also sure to have an effect on the astronomer's "spirit of place." What that spirit of place will be like ultimately will depend upon what is preserved, how it is preserved, and--most of all--where it is preserved.

Touching Base with Tycho

The Tycho Brahe Museum is located on the island of Hven, in Swedish territory. Passenger boats serve the island from Copenhagen (Denmark) and Landskrona (Sweden).

WHEN TO VISIT The museum is open from late April through mid-September. Tours are available on summer weekends and daily during July.

ACCESSIBILITY The Stjerneborg excavation/replica is not wheelchair accessible.

POINTS OF CONTACT For more details or tour reservations call Goran Nystrom at +46 418 72530 or write him at or at Kulturforvaltning, S-261 31 Landskrona, Sweden. Visit for detailed information (in Swedish and, via a single click, in English) about the Tycho Brahe Museum.

Glimpsing Galileo's Legacy

The Museum of the History of Science can easily be reached, either by foot or bus, from the Firenze Santa Maria Novella train station in central Firenze (Florence).

WHEN TO VISIT Open every day (and on few evenings) during the summer, and on Sundays only during the winter.

ACCESSIBILITY The museum is wheelchair accessible.

POINTS OF CONTACT Piazza dei Giudici 1, 50122 Firenze, Italy; +39 055 265311. Visit for directions, hours, fees, a map, and a virtual tour in either English or Italian.

ADDED AREA ATTRACTIONS Arcetri Observatory ( is a modern research facility within a five-minute walk of the Villa Il Gioiello, Galileo's last home (which currently can be admired only from the outside, though the interior is under restoration and may open to the public someday). Both are found in the Florence suburb of Arcetri, accessible by public transit. The observatory welcomes visitors with advance notice; call (+39 055 2752 1) or write Laura Mazzucconi ( or Emanuela Masini ( to inquire or to book a guided tour.

House Visitwith the Herschels

The William Herschel Museum is located in Bath, approximately 160 km west of London, and can be reached by train, bus, or car.

WHEN TO VISIT Open from early February through the end of November on weekday afternoons (except Wednesday) and weekends from 11 a.m. to 5 p.m.

ACCESSIBILITY Wheelchair access is limited to the ground floor.

POINTS OF CONTACT 19 New King St., Bath, England BA1 2BL; +44 (0)1225 311342. Check index.html for maps, hours and dates of operation, admission fees, directions, and other information.

Mastering Mount Wilson

Operated as a research and educational facility by the Mount Wilson Institute under agreement with the Carnegie Institution of Washington, the 1,700-meter-high Mount Wilson Observatory is about 32 km from the intersection of the Angeles Crest Highway and Interstate 210 in La Canada-Flintridge, California. Public transit to the mountaintop complex is unavailable.

WHEN TO VISIT The grounds are open daily from 10 a.m. to 4 p.m. year round, weather and wildfires permitting (the observatory can become snowbound, and the surrounding Angeles National Forest can burn).

ACTIVITIES From early April through late October the Mount Wilson Observatory Association offers free walking tours starting at 1:00 p.m. on Saturdays and Sundays.

OBSERVING OPPORTUNITY Contact the Mount Wilson Institute for information on renting the 60-inch telescope for a night of observing.

ACCESSIBILITY Many of the walking tour's venues, such as the 100-inch telescope viewing portal, are not wheelchair accessible.

POINTS OF CONTACT Mount Wilson Institute, PO Box 60947, Pasadena, CA 91116 USA;; 626-793-3100. Check the Mount Wilson Observatory Association's Web site ( for updates, special programs, directions, and an excellent 3-page PDF-format visitor's guide to the complex.

Looking Up from Lick

Sitting atop 1,200-meter-high Mount Hamilton, Lick Observatory is a one-hour drive from San Jose, California. Public transit is unavailable.

WHEN TO VISIT Open to daytime visitors nearly every day of the year, on weekday afternoons from 12:30 until 5, and from 10 a.m. to 5 p.m. on weekends.

ACTIVITIES A free 15-minute talk under the dome of the 36-inch refractor takes place twice hourly. Views of the 120-inch Shane reflector are likewise free of charge.

Tickets to the Summer Visitors Program, which features lectures and nighttime viewing, must be booked in advance by calling the University of California, Santa Cruz, ticket office at 831-459-2159. The same goes for the Music of the Spheres program of summertime concerts and astronomy lectures.

ACCESSIBILITY The 36-inch refractor always is wheelchair accessible, but wheelchair users must arrange in advance to view the Shane reflector. For the Summer Visitors Program and Music of the Spheres concert/lecture series, those with limited mobility should state their needs when booking tickets and are advised to communicate those needs to Lick's on-site staff (408-274-5061 or as well.

POINTS OF CONTACT UCO/Lick Observatory, University of California, Santa Cruz, CA 95064 USA;; 408-274-5061.

ADDED AREA ATTRACTION While you are in the San Francisco Bay area, check out the renewed and vastly expanded Chabot Space and Science Center (www or 510-336-7300), whose historic 20-inch and 8-inch refractors and brand-new 36-inch reflector generally are available for observing from Chabot's spectacular new location high in the Oakland hills. Chabot's facilities are largely wheelchair accessible, though the eyepieces of the large refractors are not. Improvements to make observing sessions with the 36-inch fully accessible are in the works; call or write for details.

Lowell's Legacy

Lowell Observatory is a short drive or taxicab ride from downtown Flagstaff, Arizona, which in turn is a two-hour drive from the Phoenix, Arizona, airport. Flagstaff rests at the junction of two major interstate highways (I-17 and I-40) and is a stop on Amtrak's Southwest Chief passenger train line. Meteor Crater and the Grand Canyon are nearby.

WHEN TO VISIT Lowell's grounds, gift shop, and interactive visitor center are open nearly every day of the year.

ACTIVITIES Daytime admission (for a modest fee) includes a walking tour of Mars Hill, conducted two or three times daily. Evening admission (likewise affordable) includes astronomical viewing, weather permitting, and a talk about the night sky.

ACCESSIBILITY Most of the attractions on Mars Hill are wheelchair accessible, with the notable exceptions of the Pluto discovery telescope and the eyepiece of the 24-inch Clark refractor.

POINTS OF CONTACT 1400 W. Mars Hill Rd., Flagstaff, AZ 86001 USA;; 928-774-3358

ADDED AREA ATTRACTION Ninety-minute-long private tours of Anderson Mesa can be booked through Kevin Schindler (kevin@ or 928-774-3358, ext. 210) and are not wheelchair accessible.

Peering About at Palomar

Palomar Observatory sits on the broad 1,700-meter-high summit of Palomar Mountain, a two-hour drive from downtown San Diego, California, and three hours from Los Angeles. Exit Interstate 15 at State Highway 76 eastbound and follow the latter for 25 miles, until County Road S-6 exits to the left and winds its way up steep mountain slopes to the observatory gates. Public transit is unavailable.

WHEN TO VISIT Open from 9 a.m. to 4 p.m. daily, except December 24th and 25th. Note that snow can force the observatory's closure, as can fires in the surrounding Cleveland National Forest.

ACTIVITIES Wheelchair-accessible guided tours of the 200-inch Hale Telescope are available to educational groups by reservation; call the Palomar Observatory office at 626-395-4033. As of this writing a few special nighttime visits are being managed by the Reuben H. Fleet Science Center--itself a worthy destination for the astronomically inclined--in San Diego's Balboa Park ( or 619-238-1233).

ACCESSIBILITY Palomar Observatory's gift shop and museum are wheelchair accessible, and while the viewing gallery for the 200-inch telescope is not, elevator access to the interior of the 200-inch dome currently is granted three times daily (at 9:30 a.m., 1:00 p.m., and 3:30 p.m.).

POINTS OF CONTACT; 626-395-4033; Palomar Observatory, 105-24 Caltech, Pasadena, CA 91125 USA.

Hallowed Groundin Holmdel

The microwave horn that discovered the cosmic microwave background radiation sits on private property on the Lucent Technologies campus, just off the Garden State Parkway near Exit 114.

ACCESSIBLE NO LONGER Tours of inspection are not available to the general public at this time. However, qualified organizations and individuals may contact Lucent Technologies for additional information about the Horn Antenna at or Horn Antenna Information, Bell Laboratories, 600 Mountain Ave., 3B-415, Murray Hill, NJ 07974 USA.

* This dimension (6 meters) is the primary mirror's focal length, not its aperture.

DAVID DEVORKIN is curator of the history of astronomy at the National Air and Space Museum, Smithsonian Institution, where the "Explore the Universe" exhibit (S&T: March 2002, page 62) will remain on display at least through 2010. His most recent books include Henry Norris Russell: Dean of American Astronomers (Princeton University Press, 2000) and Beyond Earth (National Geographic Society, 2000).
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Author:DeVorkin, David H.
Publication:Sky & Telescope
Geographic Code:1USA
Date:Nov 1, 2003
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