The first attraction on this walk is a sundial by the artist Catherine Podolski. This sundial is located at the house of the artist, who focuses on ceramics, and was made in 1971.
- This house (number 152) has an altimetric point on the left. When this point was measured on February 9, 2018, it was 61,819 meters above sea level.
- At this roundabout, you can see a Foucault pendulum. It is a blue steel structure with a nylon thread suspended from it. A nylon thread is attached to the top, from which a gold-colored weight hangs.
On March 26, 1851, the French physicist Léon Foucault demonstrated that the Earth rotates on its axis with his construction in the Pantheon in Paris. A pendulum swings back and forth, but because the Earth rotates on its axis, the weight's pendulum motion changes. In the original experiment, the pendulum was placed above a container of sand, so the change in the pendulum's motion was clearly visible. This artwork (called "Pensée verticale") is striking because the changing pendulum motion cannot be observed, and the water beneath the pendulum also makes it difficult to set it in motion.
- On one of the houses on this street stands a sundial from 1996 by P.P. Struye. At the bottom of the sundial is the motto "SICUT DONAT SOL LUCEM AMOR VITAM." This means "Just as the sun gives us light, love gives life." Above the bench by the sundial, there is also more information on how to use the sundial to determine the correct time.
- At the Auderghem cultural center, there is another section of the "Ruimte voor Muco" (Space for Muco) project. Here you can catch a glimpse of the planet Mercury, which has a diameter of 12 cm. This planet is the smallest in our solar system. The artwork was inaugurated on May 16, 2004.
This scale model is an initiative of the Belgian Association for the Fight against Cystic Fibrosis, which organises an annual national mucus day. In 2004, this day was organised for the tenth time and, in honour of this anniversary, ten works of art were installed that represent the link between “the world” and the constant battle that cystic fibrosis patients wage against their disease. These are a symbol of solidarity. The Earth and the Moon are located on the driveway of the Royal Observatory in Uccle.
- Can you find the altimetric point next to the bridge, 30 cm above the second step? At this point, you are exactly 56,638 meters (measured on January 1, 1981) above sea level.
- At the end of the walk, you will see a symbolic representation of the planet Venus.
This Venus is part of a scale model (1/40,000,000) of space. Venus was inaugurated on October 2, 2004, and it is by the artist Tim Roosen.
Extra:
To shorten the walk, you can skip the sundial P.P. Struye. You can do this after passing Foucault's pendulum by taking the stairs to the railway walk instead of going under the bridge (this point is just after you pass a climber on a house).
The walk crosses the "Green Walk." This 60 km walk takes you around Brussels and is divided into 7 sections.
Walk around and through the Observatory (It's possible to shorten the route near the Mahsa Amini garden)
Sights
- At the Observatory:
At the Observatory itself, you can see the Earth and the moon. These are part of a 1/40,000 scale model of the solar system spanning the entire country. This scale model was designed by Tim Roosen, and the statues were installed at the observatory in 2004, meaning they have been there for over 20 years!
- Statue of King Baudouin on Charles Lagrange Square:
A statue of King Baudouin (1930-1993), created by Uccle sculptor Elisabeth Barmarin, has stood here since 1996. King Baudouin had a lifelong interest in astronomy and regularly visited the Observatory. In 1980, King Baudouin accepted the honorary presidency of the oldest astronomical society in Belgium, the SRBA. The statue is oriented so that it appears as if the king is about to enter the Observatory.
The statue can also serve as a vertical gnomon. When the monarch's shadow falls in the center of the bluestone tiles, true noon has arrived in Uccle.
Charles Lagrange (1851-1932), after whom the square is named, was an astronomer and professor at the Royal Military Academy and director of the scientific headquarters of the Royal Academy. He and several others founded the journal Ciel et Terre of the Belgian Astronomy Society.
In 1882, he traveled to Santiago, Chile, with Louis and Joseph Niesten, to observe the transit of Venus.
He was involved in the Observatory's move to Uccle as assistant to then-director Houzeau, and became the Observatory's director himself between 1898 and 1900, after which Georges Lecointe was appointed his successor.
- Hamoirlaan 28b:
Amateur astronomer and nature lover Paul Dupont (1878-1949) once lived here. He was president of the Belgian Astronomy Society from 1937 to 1939.
He built this house in 1923, incorporating a library, laboratory, and a 5.75-meter-diameter observation dome. This dome housed a 16-cm Bardou refractor from Paris on an equatorial mount. There was also a 13-cm refractor with photographic capabilities. There was also a small transit instrument in the garden with a 3.5 cm aperture to synchronize the clock time with Sidereal Time. He recorded the annular eclipse of April 17, 1912, and these images are among the best available.
- Linkebeek (mural): At the intersection of Alsembergsesteenweg and Rue de Linkebeek, you can admire a beautiful mural of the Observatory.
- Dieweg Cemetery:
This cemetery contains the grave of Hergé, who also lived on this street. Hergé had close ties and often visited the Observatory. We see this special relationship reflected in the comic strip "The Mysterious Star," in which Tintin seeks advice at the Observatory.
- Geodetic point:
An altimetric point is located near the railway viaduct (middle pillar) on Sint-Jobsteenweg (south side, 105 cm from the right, 47 cm above the ground). Determining the shape and size of the Earth is the main goal of geodesy. By modeling the Earth, we can describe the position of all points on its surface using geographic coordinates. Can you find the point? Look at the photo to see what to look for.
This route runs from the Yser metro station to the Louise metro station. Along the way, we encounter:
- A sundial was installed in a newly built office building at Boudewijnlaan 12 in 2005. A metal sphere suspended by a tension cable serves as a shadow caster. This is the largest vertical sundial in Belgium. In addition to vertical hour lines, there are also horizontal date lines. At the top, there is a line for astronomical winter, while at the bottom, a line indicates the beginning of astronomical summer, and in between, there is a date line for the spring and autumnal equinoxes. At the request of the architects Clernaux and Pinon, the sundial was adjusted to the geographical time difference. The hour numerals at the bottom indicate summer time. Jan de Graeve designed the sundial, and Willy Leenders calculated the hour and date pattern.
- On Place De Brouckère, we find the 19th-century Hotel Métropole. This hotel is associated with the Solvay Congresses, prestigious meetings focusing on physics and chemistry. The first was organized in 1911 by Ernest Solvay. This was also the first international meeting ever on physics. The first Solvay Congress, focusing on astronomy, was held in 1958.
- In the Cathedral of St. Michael and St. Gudula, you can see a brass line running across the black tiled floor, almost 34 meters long. This noon line allows us to determine exactly when it is noon.
The noon line was constructed in 1836 by Adolphe Quetelet and was part of a major project by the new Belgian government to eliminate time differences in the various cities. This became necessary because a train network was being built in Belgium, and it was crucial that the trains run according to the same time indication. The noon line in the Brussels Cathedral was the first to be built, and Quetelet would later build nine more, bringing the total number of noon lines in Belgium to 41. Quetelet chose the church for its ideal north-south orientation and because he felt it was important for the public to have access to this new time display.
The noon timeline works thanks to a small opening, or oculus, in the thick stone central mullion of the stained-glass window of the south transept. When the sun is directly due south, the sun shines through the opening onto the noon timeline in the church. The best time to observe the noon timeline is in the summer when the sky is blue. Due to a high-rise building on Sint-Gudulaplein, the sun is obstructed from mid-October to early March.
The noon timeline that can be admired in the church is not the original one created by Adolphe Quetelet, which was made of copper. Between 1982 and 1996, the church was restored, and the floor was also re-laid. This caused the original noon timeline to disappear. But thanks to the efforts of Paul Pâquet (then director of the Observatory) and the many gnomics enthusiasts, a new brass sundial was inaugurated in 2001 after further renovations. The new sundial was constructed with the help of Walter Lavrauw's design office, who, together with André Koeckelenbergh, carried out the necessary measurements (now using modern instruments).
- We pass by the Koudenberg, where, between the Centre for Fine Arts and the 'Old England' music museum, we see a sundial on a Neo-Renaissance building with Gothic features. This is the former 'Pharmacie Delacre' from 1895. The building was designed by architect Paul Saintenoy. The sundial's mosaic was created by the Italian Silvio Tolomei. The hour numerals are displayed in Arabic characters.
- Just in front of the Palace of the Academies building stands a marble statue of Adolphe Quetelet. The palace itself is a neoclassical building dating from 1823-1828. Sculptor Charles-Auguste Fraikin was commissioned to create a statue in honor of Adolphe Quetelet, who, besides being the founder of the Royal Observatory, was also secretary of the Royal Academy of Belgium (which he joined at the age of 24) and founder of the natural sciences of the Society. The statue was unveiled on May 11, 1880.
The International Astronomical Union (IAU) was also founded in this palace in the summer of 1919. This union would, among other things, realize the Carte du Ciel project.
- After the walk, you can take metro lines 2 or 6 from Trône to return to the starting point.