Astronomy and heritage in Extremadura: archaeoastronomy
Archaeoastronomy: a new field of research
Archaeoastronomy is a fairly new field of research, somewhere between astronomy and the social sciences. In Spain, its development began with the studies of Michael Hoskin, a British astronomer who was interested in the orientation of megalithic structures in the Mediterranean, including the site of the Dolmens of Antequera, a UNESCO World Heritage Site since 2016. Juan Antonio Belmonte has been collaborating with this Cambridge University professor since the 1990s and is one of the most outstanding figures in this field in our country. His work has contributed, among other things, to the archaeological site of Risco Caído and the Sacred Mountains of Gran Canaria being declared a World Heritage Site by UNESCO.
Since Palaeolithic times, humans have observed the sky closely, which has allowed them to become aware of its cyclical phenomena and has helped them to orient themselves in both time and space. The different cultures that have developed across the globe have tried to explain this connection with the cosmos in a variety of ways. These cosmologies are reflected in architecture, mythology, literature, and landscape design. Archaeoastronomy studies past astronomical practices and their reflection in monuments that have survived to the present day.
Extremadura is an autonomous community in which astronomy and astro-tourism are actively promoted. We invite you to read this article on astronomy and astro-tourism in Extremadura.
Megaliths in Cáceres
In the border region of Valencia de Alcántara (Cáceres) and neighbouring areas in Portugal lies one of the largest megalithic sites in Western Europe, dating from around 4,000 BCE. This complex is made up of more than 50 dolmens that are systematically oriented towards the east, coinciding with the rising of the sun or the full moon at some time of the year. For this reason, it is considered "the best example of astronomical orientation in Europe" (Belmonte and Hoskin, 2002). Many of them could mark "the rising of the full moon at or immediately after the autumnal equinox" (Belmonte, 2002).
Seven-stone dolmens or antas were megalithic tombs composed of a large granite slab that served as a headstone, followed by three other stones on each side, forming a circular chamber. This chamber was covered with another large granite slab and had an access corridor. These dolmens oriented in relation to the sky not only had a funerary function but were also important places of worship for these peoples. They are also an example of how important it was for the survival of these populations to mark the seasonal changes in their territory.
Megaliths in Badajoz
The province of Badajoz also has several megalithic works. On the one hand, in the area around Mérida, we find the dolmens of Lácara and Magacela. Both tombs have the same orientation towards the east, which corresponds to the rising of the sun on dates close to the spring and autumn equinoxes, as is the case with the dolmens in Cáceres.
On the other hand, in the vicinity of Almendralejo is the Huerta Montero Tholos, another type of megalithic tomb dating from the 3rd millennium BCE, whose orientation coincides with the sunrise on the winter solstice. On that day, at dawn, the sunlight illuminates the bottom of the chamber and moves towards the entrance as the sun rises over the horizon, producing an impressive luminous effect.
In Jerez de Los Caballeros we also find the Tholos Granja del Toriñuelo, which is oriented towards the east, coinciding with the sunrise on dates close to the spring and autumn equinoxes.
Tartessian culture in Extremadura
In the course of the first millennium BCE, just before the arrival of the Romans on the peninsula, Extremadura was influenced by the Tartessian culture of the peoples to the south, creating a unique idiosyncratic cultural mix. Although archaeo-astronomical studies of Tartessian culture are still scarce in this region, the different construction phases of the monumental complex of Cancho Roano in Zalamea de la Serena are oriented towards the rising of the sun.
The Roman heritage in Extremadura
In 218 BCE, Roman legions landed on the Peninsula and a few years later arrived in Extremadura. After several battles with the indigenous peoples, they settled in the region. The impressive cultural legacy they left behind can still be seen today.
Roman cities are a clear example of archaeoastronomy because the cosmos played a very important role in their location and orientation. Without going any further, Emerita Augusta (Mérida), founded in 25 B.C.E., may be considered to be oriented to "Venus in its most extreme position to the south when it appears as the evening star, shortly before sunset on the western horizon" (Rodríguez-Antón et al, 2018). One explanation for this orientation could be that the Julio-Claudian dynasty that founded this city considered itself a descendant of the Roman goddess Venus.
Metellinum, today's Medellín (Badajoz), is also another archaeoastronomical vestige in the region. Its present-day Calle Palacios is the decumanus, the axis that the path of the Sun was supposed to follow, and which ran perpendicular to the cardo, which had a north-south orientation. The important thing to note in this case is that in most Roman cities, despite the rugged terrain, this orientation was maintained, coinciding with sunrise or sunset.
Also, in the province of Cáceres lies Cáparra, an ancient Roman city that is famous for a four-pillar arch located at the intersection of the decumanus and cardo axes. It has a similar orientation to that of Emérita Augusta, following Venus at its sunset.
The Roman camp at Cáceres el Viejo has an orientation that coincides with that of other Roman camps that glorify the 21st of April, the date of the foundation of Rome. Thus, in Britain, many camps were oriented to coincide with the sunset of 1 March, the day dedicated to Mars, the Roman god of war, while in North Africa, in Algeria, the camp of Diana Veteranorum is oriented towards the sunset of 21 April, as is the camp at Cáceres, and the sunrise of 1 March.
The mark of Christianity
The arrival of Christianity brought about a cultural transformation in every sense of the word. Not surprisingly, this change was also reflected in architecture. Churches became a central element in town planning. One thing that seems to be a constant feature is a predilection for the apse of churches to face east, with a preference for dates close to the equinox. In the same way, the aim was to avoid an orientation coinciding with the solstices, as these dates were identified with pagan celebrations.
Although there are few archaeoastronomical studies of the churches of Extremadura, we have some analyses focused mainly on the city of Merida. The first of these is the church of Santa Eulalia, which houses the remains of the martyr, patron saint of Mérida. The original temple was built in the 5th century and would have been oriented towards the sunrise during the astronomical equinox in March. Likewise, the Xenodochium of Santa Eulalia, a hostel and hospital, built in Visigothic times to accommodate people who came on pilgrimages to visit the martyr's burial mound, has the same orientation as the church of Santa Eulalia. In the vicinity of Mérida, the basilica of Casa Herrera, built between the 5th and 6th centuries, would be oriented towards sunrise on April 23 or August 21 of the Julian calendar. In the province of Cáceres, the Ermita de Santa Lucía del Trampal is the only Visigothic building still standing in the southern half of the Iberian Peninsula. It is another example of early Christian construction oriented towards the equinox.