Transit of Venus
Photo of the June 8, 2004, transit of Venus by Edwin Aguirre and Imelda Joson
A First-in-a-Lifetime Transit
By Imelda B. Joson
Watching the tiny silhouette of the planet Venus slowly cross the face of the Sun doesn’t evoke the same drama and excitement as experiencing a total solar eclipse, but what makes a transit so unique is its rarity and historical significance.
Astronomers from the 17th to the 19th centuries were interested in such rare alignments of the three celestial bodies — the Sun, Venus, and the Earth — because they provided a way of figuring out the value for the solar parallax, which was astronomy’s holy grail. The solar parallax formed the basis for measuring the distance from the Earth to the Sun — the astronomical unit, or AU — which was a standard yardstick for determining astronomical distances.
The last time a transit of Venus was observed was in 1882. For the planet’s historic, first-in-a-lifetime transit on June 8, 2004, TravelQuest International and Sky & Telescope magazine organized three separate tours to Italy.
As S&T’s Photo Editor, I led one group in watching the event from the Vatican Observatory. Edwin, as an S&T Associate Editor, led a second group at the Astronomical Observatory of Rome, while Richard Tresch Fienberg, S&T’s Editor in Chief, headed the third one at Arcetri Observatory in Florence.
Edwin and I began our 2004 Transit of Venus adventure on the afternoon of Friday, June 4th, with an overnight trans-Atlantic flight to Rome via Zurich, Switzerland. During the nine-hour flight, I couldn’t help but think of the hardships and challenges that astronomers of earlier generations had to endure in order to observe and study such events.
It took them months, if not years, to reach their observing sites — they hauled tons of equipment, they were at the mercy of the weather, and communications took forever. In our case, before I could even take a nap, we arrived at our destination.
After hooking up in Frascati with TravelQuest International’s Aram Kaprielian and our tour guide and inbound tour operator, our group proceeded to the Astronomical Observatory of Rome in Monte Porzio Catone and the Vatican Observatory in Castel Gandolfo to confirm that both facilities were ready for the arrival of our respective tour groups later that day.
The weather that Saturday evening and Sunday morning was quite bad — it was either overcast or rainy all day long. But the astronomers from both observatories assured us that good weather could be expected on transit day. True enough, by Sunday afternoon patches of blue skies started to appear.
Edwin’s tour got underway on June 5th. My group got together at the Hotel Villa Vecchia the following day for the welcome reception by the hotel’s swimming pool. Everyone was excited about the transit, and a few exchanged stories about previous tours they had participated in.
It’s always a joy to travel with these kinds of people — those who share the same passion as I have for chasing astronomical events (even if one has to travel thousands of kilometers) and for making new friends. We spent the rest of the evening feasting on the wonderful Italian dishes that had been especially prepared for us.
After breakfast the following morning, we took a short bus ride from the hotel to the observatory in Monte Porzio. Its director, Dr. Sergio Colafrancesco, and several of his staff showed us around the facility. We saw their wonderful collection of antique brass telescopes and transits and the archeological dig that was underway on the observatory grounds, as well as Astrolab, a modern, interactive museum geared toward public astronomy-outreach programs.
From Monte Porzio, we headed to the town of Frascati. Renowned for its Roman villas and exquisite, locally produced vino bianco (white wine), Frascati has become a favorite weekend retreat for many Romans due to its proximity to the city (about 22 kilometers) and its crisp, clean air. At the center of town lies the imposing Villa Aldobrandini, famous for its gardens and fountains.
Several people from our group decided to explore the town on their own, while some of us went with our guides to the back part of town where we tasted some Frascati wine and cheese. Although I’m not much of a wine or cheese aficionado, my experience there had turned me into one. No wonder travel books and websites never fail to mention Frascati’s wines and delicacies.
One thing that fascinated some members of our group was the gingerbread that was shaped into a three-breasted woman and was being sold in a number of stores. A member of our group decided to ask one of the locals what it meant. The explanation given was that two of the breasts were for milk while the third one was for wine!
From the town’s central square we boarded the bus for the trip to a family-run vineyard and winery where lunch was served, fiesta style. The centerpiece of the meal was a whole roasted pig.
The group then headed to the small, quaint town of Grottaferrata, where they took a relaxing afternoon stroll and visited the town’s beautifully preserved churches. I, on the other hand, proceeded to Castel Gandolfo to check on the preparations for the transit the following day. The group joined me later that afternoon, when they arrived for a tour of the historic Vatican Observatory.
The Pope’s Observatory
Officially known as the Specola Vaticana, the observatory is situated within the Papal Palace, on the Alban Hills some 35 kilometers southeast of Rome. The palace, which overlooks the picturesque Lake Albano, was the summer residence of then Pontiff John Paul II.
According to Father Christopher J. Corbally, S.J., the Vatican Observatory is one of the oldest astronomical research institutes in the world. Its roots date back to the late 1500s, when Pope Gregory XIII appointed a commission to reform the old Julian calendar in use since 46 B.C. (The resulting Gregorian calendar was adopted in 1582 and is our familiar calendar today.)
From 1789 to 1821, the observatory was housed in the Tower of the Winds within Vatican City. In 1891, Pope Leo XIII formally refounded the Specola Vaticana and located it on a hillside behind the dome of Saint Peter’s Basilica.
Rome’s urban growth, however, eventually brightened the night sky to such an extent that faint stars could no longer be studied. In 1935, Pope Pius XI moved the observatory to its current home in Castel Gandolfo.
With the burgeoning population of Rome, the skies over Castel Gandolfo again became too bright. Thus, in 1993, the Specola, in collaboration with the University of Arizona’s Steward Observatory, established a second research facility — the 1.8-meter Vatican Advanced Technology Telescope (VATT) atop Arizona’s 10,500-foot Mount Graham.
After the welcome remarks from our host, Brother Guy Consolmagno, S.J. (whom we had first met during the 1999 Vatican Observatory Summer School), several Jesuit astronomers escorted us for a behind-the-scene look inside the Papal Palace.
In addition to seeing the great 16-inch Zeiss refractor, we visited the library where we were shown the observatory’s collection of rare astronomical books — works by famous astronomers such as Galileo, Copernicus, Kepler, Tycho, Newton, and many others. The highlight of the trip was seeing the Vatican’s world-famous meteorite collection.
The visit also gave us the opportunity to set up our equipment on the observatory’s spacious roof deck. After a long, productive day, it was time for dinner! We strolled through the town of Castel Gandolfo to a family-style restaurant that offered a splendid view of Lake Albano. Again, it was an evening of Italian gastronomical delights.
The Main Event
On Transit Day, June 8th, we arrived at the observatory around 6 a.m. The weather looked perfect! Except for a few thin clouds near the horizon, the entire sky was clear and blue. First contact would not take place until 7:20 a.m. local time, so we had plenty of time to do some last-minute adjustments to our photographic and video setups.
The event started right on schedule, when Venus’s disk first touched the southeastern limb of the Sun. It was a very exciting moment — imagine, witnessing an event that had not been seen by human eyes for nearly 122 years!
Some members of the group using telescopes fitted with hydrogen-alpha filters were able to see the planet’s silhouette ahead of those using scopes with white-light filters.
I can’t forget the view through a Tele Vue 76 refractor fitted with a 60-mm H-alpha filter. Venus’s deep-black disk appeared quite large, and the prominences along the solar limb made for a very dramatic scene.
Meanwhile, other members of the group chose to follow the event on a TV monitor that was hooked up to a video camera at the prime focus of the 16-inch refractor.
I also took the time to call my mom in Boston, where she was watching the celestial drama unfold low in the morning sky. (Before leaving for Italy, we prepared mylar-filtered binoculars for her to use.) It was amazing how modern technology had allowed us to share observations of the same event in real time from both sides of the Atlantic!
Just before third contact, at 1:05 p.m. local time, a few cumulus clouds started to roll in; fortunately, they didn’t hamper our view. The transit officially ended at fourth contact, at 1:24 p.m.
Photo courtesy Dennis di Cicco
Afterward, we packed our gear and then headed back to the hotel for a well-deserved afternoon rest. A few members of the group, still “pumped up” from a very successful transit observation, decided to visit Hadrian’s Villa, the spectacular country retreat built some 2,000 years ago by Emperor Hadrian near the town of Tivoli.
After an early breakfast we boarded our bus for the drive to Ostia Antica. There, we were met by local guides who took us on a tour of the ruins of this ancient seaport city.
Ostia comes from the Latin word ostium, which means “mouth,” since the city used to be at the mouth of the Tiber River. Due to silting, however, the shoreline moved about four kilometers seaward, leading to the city’s decline beginning in the 4th century A.D.
Walking along the silent, narrow, cobbled streets of Ostia that morning was like traveling through time. To see the ruins of an entire city firsthand was just amazing! The ancient temples, houses, bakeries, gardens, public baths, and theater are all nicely preserved, and the floor tile mosaics are most impressive.
Our next stop was for lunch at a local seafood restaurant. It was late afternoon when we finally arrived at our hotel in Rome, the Domus Sessoriana. Formerly a monastery, the Domus is adjacent to the church of Santa Croce in Gerusalemme. This church was founded around A.D. 320 to house the relics collected by Saint Helena, the mother of Emperor Constantine, during her visits to the Holy Land.
As the Sun was setting, we gathered on the hotel’s roof deck to toast our arrival in the Eternal City. Later in the evening, we went to a restaurant to sample authentic Roman cuisine.
Touring the Eternal City
We started our tour of Rome at the Colosseum. This magnificent arena and amphitheater built around A.D. 80 could sit up to about 50,000 spectators. It’s considered to be one of ancient Rome’s greatest architectural and engineering achievements.
From the Colosseum, we proceeded to the Arch of Constantine and then on to the Roman Forum, the center of activity during the height of the Roman Empire. From the Forum, we walked up the hill to the Campidoglio, the seat of the city’s modern-day government. Michelangelo designed the Piazza Campidoglio in 1538.
Our next stop was at the Pantheon. Originally built as a Roman temple around A.D. 120, the Pantheon was converted into a Catholic Church around 609, when it was given to Pope Boniface IV by Emperor Phocas. Here we saw the tomb of the famous Renaissance painter Raphael, as well as those of the Italian monarchs Victor Emmanuel II and Umberto I.
Later in the afternoon, we visited the Trevi Fountain, made famous by the 1954 movie, “Three Coins in the Fountain.” This magnificent work of art is Rome’s largest and grandest fountain. Nicola Salvi completed it in 1762. Before returning to the hotel, we made a quick stop at the famous Spanish Steps.
On June 11th, Aram took us to the cupola of Saint Peter’s Basilica, where we had a bird’s eye view of Saint Peter’s Square as well as Rome and beyond. The scenery was breathtaking! On the way up, we saw up close the tile mosaics on the inside walls of the basilica’s great dome. The Baroque bronze canopy designed by Bernini over the main altar could also be seen just below us.
After enjoying the view from the cupola, our group then went to see the magnificent, priceless treasures of the Vatican Museum. Going through its Map Room, one can’t help but admire the hallway’s exquisitely detailed ceiling frescoes. The Egyptian, Etruscan, and other collections of the museum are some of the world’s finest.
The highlight of our tour, of course, was the Sistine Chapel. Here we saw Michelangelo’s famous ceiling frescoes, depicting scenes such as the Creation of Adam and The Last Judgment. The Vatican Museum is truly a place where one can spend a lot of time and yet not get tired of admiring the fabulous artwork it contains.
That night we had our farewell dinner at a restaurant in Trastevere. It was a pleasant evening, but a sad one at the same time since it was the group’s last day together. After enjoying each other’s company for a week, witnessing a rare astronomical event, touring ancient sites, and appreciating the history, culture, and hospitality of Rome together, it was time to say goodbye.
Aram made the occasion even more memorable by making special arrangements to have an outdoor dinner, complete with live performers who serenaded us with love songs. We took this opportunity to exchange e-mail addresses and phone numbers, and to say goodbye — for now — to our newfound friends. The entire trip was truly an unforgettable, life-changing experience!
A Wondrous Solar Crossing
By Edwin L. Aguirre
A transit of Venus across the face of the Sun is one of nature’s rarest celestial phenomena. That was why the planet’s solar crossing on June 8, 2004, was an eagerly anticipated event. It was the first such transit to be observed in almost 122 years and only the seventh since the invention of the telescope in the 1600s.
Unlike the astronomers of yesteryear who had to endure months, even years, of arduous travel to reach their observing sites, and had to contend with wars, diseases, insects, and extreme weather conditions, the modern transit observer could now travel in luxury and style. This difference is evident in how we describe such trips: in the past, astronomers mounted expeditions; today, we have tours.
Before, astronomers had to plan their trips years in advance, obtain funding from their respective monarchs or governments, and haul tons of equipment to their viewing sites, only to be clouded out on transit day.
The modern transit traveler could now choose the best location based on the latest weather-satellite data, arrive at his or her destination by jet, enjoy five-star hotel accommodations and sumptuous meals, proceed to the observing site in air-conditioned comfort, capture the transit using small, portable equipment that could record the event in unprecedented clarity and detail, and do some leisurely sightseeing afterward. What a difference!
Although no important scientific breakthroughs were expected during the 2004 transit (the Sun-Earth distance had already been measured with great accuracy using ground- and space-based observations), its allure to amateur astronomers was not diminished by this fact.
The Eternal City
For Imelda and me, our adventure began upon our arrival at Rome’s Leonardo da Vinci (Fiumicino) airport on June 5th.
We rendezvoused with TravelQuest’s Aram Kaprielian as well as with our tour guide and inbound tour operator at a hotel, and then proceeded to our two primary observing sites — the Astronomical Observatory of Rome at Monte Porzio Catone and the Vatican Observatory at Castel Gandolfo. There we met with the astronomers to make sure all the arrangements were in place. Afterward, we went straight to our hotel in Rome, the Domus Sessoriana.
Once a monastery, the newly opened Domus features 19th-century ceiling-high paintings and terra cotta floors. Right next to the hotel is the church of Santa Croce in Gerusalemme. Saints adorn the facade of this important pilgrimage center founded in A.D. 320. Inside are relics of the cross, nail, and crown of thorns brought from Jerusalem by St. Helena, the mother of Emperor Constantine.
That evening, we had cocktails on the hotel’s roof terrace to toast the arrival of the 40 members of our tour group to the Eternal City, before heading to a local restaurant to feast on Italian culinary delights.
The following morning, our group embarked on a walking tour of ancient and baroque Rome. No visit to the city would be complete without a trip to the Colosseum. Completed around A.D. 80, this great amphitheater could accommodate up to 55,000 spectators and was the venue for gory matches between gladiators and wild animals.
Other renowned attractions we visited included the Forum, a complex of columns, arches, temples, churches, and basilicas that was the center of political, commercial, and judicial life in ancient Rome; the Campidoglio, which was the “Capitol” or center of the ancient Roman world; the Pantheon, or the “temple of all the gods,” a monumental 2,000-year-old domed structure that is one of the largest surviving temples of ancient Rome; the magnificent Trevi Fountain, designed by Nicola Salvi in 1762 (tradition has it that a coin thrown into the water guarantees a visitor’s return to Rome); and the lively Spanish Steps, one of the city’s most dramatic and distinctive landmarks that has long been the haunt of local and foreign tourists and promenaders.
Back at the hotel, I gave a talk to the group, touching on transit history, what to expect on transit day, and how to photograph the event. I also showed an animation of the 1882 transit assembled from still images obtained by astronomer David Peck Todd from Mount Hamilton in California, and played the Transit of Venus March composed by John Philip Sousa in 1883. (Imelda had to leave to welcome and join her tour group, which arrived that afternoon.)
Early the next day, we were off to the smallest sovereign state in the world — Vatican City. Here we marveled at the magnificent facade of St. Peter’s Basilica as well as its obelisk and fountains and the perfectly symmetrical colonnade that lines the vast square in front of the basilica.
We then took a trip up to the cupola atop St. Peter’s dome. At 452 feet high and 138 feet wide, this dome designed by Michelangelo is one of the largest in the world. The view of central Rome and the adjoining Papal Gardens from the cupola was breathtaking!
We then proceeded to the Vatican Museum, whose galleries and long corridors contain statues, murals, tapestries, and other priceless artifacts. Of course, the highlight of this visit, and one not soon to be forgotten, are Michelangelo’s spectacular ceiling frescoes in the Sistine Chapel, which depict such scenes as the Creation and The Last Judgment.
From the chapel we strolled inside the basilica, where we saw one of Michelangelo’s marble masterpieces, the Pietà, completed when the Florentine artist was only around 25 years old.
After a long, fulfilling day, we were back at the hotel for dinner and to prepare for the Big Event the following day. Wake-up call was set at 4 a.m.
Our biggest worry from the beginning was the weather. For three straight months, the weather over Rome, and rest of Italy for that matter, had been unseasonably cloudy and rainy. In fact, on the first night of our tour, it was pouring.
Fortunately, a high-pressure system had moved in, bringing clear, blue skies and abundant sunshine beginning Monday, just one day before the transit. We were extremely lucky!
Transit day dawned nearly cloudless and remained that way throughout most of the day. Having experienced a half dozen total solar eclipses, wherein totality lasted only for a few frenzied minutes, Venus’s march across the Sun took place at a more leisurely pace, so it was a pleasure to watch visually and to photograph. No intense pressure here, even during the moment of contacts as the planet ingressed (entered) and egressed (exited) the solar limb.
The Astronomical Observatory of Rome is nestled on a hill in Monte Porzio Catone, about 15 kilometers southeast of Rome and just a short distance from the town of Frascati. Completed in 1965, this modern research facility specializes in the study of the Sun as well as stellar evolution, galactic structure, and cosmology.
Our hosts, observatory director Dr. Sergio Colafrancesco and scientific secretary Dr. Giuliana Giobbi, had reserved an area at Monte Porzio’s Astronomical Park especially for our group. It was located right next to Astrolab, which lies a few hundred yards northwest of the main observatory building.
This site features a flat grassy field with a clear, unobstructed view of the eastern horizon. Adjacent to our site are the ruins of the villa of Matidia Augusta, the niece of Emperor Trajan, who ruled from A.D. 98 to 117.
Over the weeks before the trip, I was wondering if I’d be thrilled and my adrenaline would start flowing at the sight of a small black dot moving very slowly across the face of the Sun. But on the morning of the transit all my doubts, all my skepticism, vanished completely. This was going to be very exciting! It was as if you were watching the event unfold with all the astronomers who had witnessed it (or had failed to see it) over the past four centuries.
First contact occurred right on schedule at 7:20 a.m. local time, with Venus’s inky disk creating an almost imperceptible “dent” on the solar limb. This dent soon became more and more pronounced, growing gradually in size as the transit progressed.
Shooting with my Nikon Coolpix 990 digital camera through a 60-mm f/8.3 Takahashi apochromatic refractor fitted with a white-light filter, I tried to capture the so-called “black-drop” effect.
Photo courtesy David Pottinger.
In this curious phenomenon, as Venus’s silhouette makes internal contact with the limb, it seems to draw a thread of blackness that distorts the silhouette’s shape. It’s an elusive effect that was first reported by astronomers during the 1761 transit. Like many observers in our group, I didn’t see or record the black-drop effect. (The seeing was very steady that morning.)
The sight of Venus creeping across the Sun’s disk was so captivating that the people in our tour group didn’t venture too far from their equipment during the six-hour-long transit. It was such a pretty sight!
As the Sun rose higher, so did the temperature. Fortunately, the humidity remained relatively low and a light breeze was blowing across the field, making the viewing conditions quite tolerable. Observers who wanted a break from the heat went inside the air-conditioned Astrolab building.
As one of the country’s pioneering science museums, Astrolab offers the public innovative astronomy shows and interactive exhibits. That day, it had a large video image of the Sun from one of the observatory’s telescopes projected on a wall so visitors could follow the transit’s progress in real time. The facility also had three PCs set up at the lobby so people could access live webcasts of the event from different parts of the world.
What made the transit especially memorable was the fact that Dava Sobel was a member of our tour group. An award-winning former science reporter from the New York Times, Dava is the author of the international bestsellers Longitude, Galileo’s Daughter, and Letters to Father.
While Venus’s transit was well underway, she autographed the hardbound copies of Galileo’s Daughter and Letters to Father that Imelda and I had brought for this very special occasion. The books are now part of our library’s collection that we will treasure forever.
Third contact took place at 1:05 p.m. local time. Again, I didn’t notice any sign of the black-drop effect (the seeing had deteriorated by then). With a minute and a half to go before last contact, scheduled at 1:24 p.m., a patch of cloud passed directly in front of the Sun, hiding it from view.
Although we missed seeing the transit’s official end, nobody complained — we saw the transit, and everyone had a great time!
After packing our gear and having the traditional group photos taken, Dr. Colafrancesco gave us a private guided tour of the observatory’s exhibits, including its fine collection of antique brass transit telescopes and rare manuscripts.
We’re truly grateful to Dr. Colafrancesco and his staff for their warm hospitality and generous support, and for making our 2004 transit of Venus tour a resounding success.
Shortly thereafter, we boarded the bus for the ride back to the hotel, tired but very happy.
The next day we traveled 25 kilometers southwest of Rome to the beautifully preserved ruins of Ostia Antica, an important commercial port and military base at the mouth of the Tiber River that once supported a population of nearly 100,000 during its peak in the 2nd century A.D.
On our tour’s last full day, we visited Frascati and Grottaferrata, stopping by a family-run winery and vineyard for lunch and to taste the famous Frascati wine before heading up the Alban Hills to admire the charming lakeside village of Nemi.
The Papal Observatory
Our last stop before heading back to the hotel was the Vatican Observatory. Called the Specola Vaticana in Italian, the observatory is located in the small, picturesque town of Castel Gandolfo, which lies some 25 kilometers southeast of Rome.
Sitting on top of a ridge 500 meters above sea level, Castel Gandolfo overlooks the tranquil, turquoise Lake Albano, formed by the collapse of an ancient volcanic crater. The town’s narrow, cobbled main street leads past quaint little cafes, souvenir shops, and a beautiful church and fountain designed by 17th-century Italian artist Giovanni Lorenzo Bernini.
The headquarters of the Vatican Observatory lies within the Pontifical Palace of the Roman Catholic Church — a four-story ocher edifice with small, shuttered windows, cloistered halls, a central courtyard, and a pair of massive wooden doors. Officially a part of Vatican City, this was where the late Pope John Paul II spent the summer months to escape Rome’s oppressive heat and humidity.
Our hosts that night were Brother Guy Consolmagno, S.J., and Father Chris Corbally, S.J., who joined us at our tour’s farewell dinner at a nearby restaurant. After a nice, leisurely meal, we headed back to the observatory for an exclusive, behind-the-scene look at its facilities.
The observatory features two domes, one housing a double astrograph (a 16-inch f/5 lens and a 24-inch Newtonian-Cassegrain reflector) and the other a Zeiss 16-inch f/15 visual refractor. Unfortunately, the dome for the double astrograph was undergoing renovation at the time of the transit, so only the Zeiss refractor was accessible to the group.
Although these instruments are no longer used for regular scientific observations, they are still being utilized for educational programs, such as the biennial Vatican Observatory Summer School.
In addition to the telescopes, the observatory also houses an important collection of photographic plates; a library of more than 22,000 books and manuscripts, including rare works by Copernicus, Galileo, Newton, and Kepler; and one of the world’s largest meteorite collections (1,086 specimens from 464 falls, including several rare lunar and Martian meteorites).
The most rewarding aspects of any tour are the special places you visit, the wonderful people you meet, and the new bonds of friendship that are forged. I’m pretty sure those who participated in our week-long transit tour brought home fond memories they will cherish for the rest of their lives.
If you missed the 2004 event, don’t despair — transits of Venus come in pairs roughly eight years apart, so you’ll soon get another chance. The planet’s next transit will take place on June 5–6, 2012, with the entire event visible from eastern Asia, the Philippines, Japan, Australia, New Zealand, Alaska, and the Pacific Ocean. We hope to see you there!
After 2012, the next pair of Venus transits will not be seen again for more than a century — on December 11, 2117, and December 8, 2125.