Equations are not being displayed properly on some articles. We hope to have this fixed soon. Our apologies.

Sparavigna, A. (2016). A Possible Astronomical Orientation of the Curia Julia in the Forum of Rome. PHILICA.COM Article number 639.

ISSN 1751-3030  
Log in  
Register  
  1211 Articles and Observations available | Content last updated 23 October, 11:45  
Philica entries accessed 3 372 496 times  


NEWS: The SOAP Project, in collaboration with CERN, are conducting a survey on open-access publishing. Please take a moment to give them your views

Submit an Article or Observation

We aim to suit all browsers, but recommend Firefox particularly:

A Possible Astronomical Orientation of the Curia Julia in the Forum of Rome

Amelia Carolina Sparavignaunconfirmed user (Department of Applied Science and Technology, Politecnico di Torino)

Published in astro.philica.com

Abstract
In previous papers, we have discussed the astronomical orientation of some Roman towns and the alignments of their main streets, the decumani, along the rising of sun and moon on solstices and major lunar standstills. Here, we start analysing the possible astronomical orientations of the buildings of the Roman Forum, the political centre of the ancient Rome. We are discussing in particular the Curia Julia, founded by Julius Caesar in 44 BC.

Article body


 

A Possible Astronomical Orientation of the Curia Julia in the Forum of Rome 

 

Amelia Carolina Sparavigna

Politecnico di Torino

 

In previous papers, we have discussed the astronomical orientation of some Roman towns and the alignments of their main streets, the decumani, along the rising of sun and moon on solstices and major lunar standstills. Here, we start analysing the possible astronomical orientations of the buildings of the Roman Forum, the political centre of the ancient Rome. We are discussing in particular the Curia Julia, founded by Julius Caesar in 44 BC.

 

 

The Roman Forum was for centuries the center of the Roman political and public life. Many of the oldest monuments and buildings of the ancient Rome are there. Some of the earliest temples are towards its southeast edge, such as the temple of Vesta and the complex of the Vestal Virgins. Other archaic shrines are in the northwest part, such as the Umbilicus Urbis and the Vulcanal, which are close the Arch of Septimius Severus.  The Senate House (Curia Julia) is also there.

The Curia that we see today is that planned and founded by Julius Caesar in 44 BC. Augustus ended its building and enriched the Forum of a temple honouring Mars. Under Trajan, much economic and judicial business were transferred away from this Forum to the larger structures of Trajan's Forum and Basilica Ulpia. However, reigning Constantine, the old Forum regained its importance, with the construction of the huge Basilica of Maxentius (312 AD) [1].

Observing a map of the Forum, such as a satellite map, we can see its main axis, having an east-west generic direction (see Figure 1). Many building are not parallel or perpendicular to the direction of this main axis, so it is difficult to imagine the original layout of the forum. It seems necessary to analyse each specific part of it, to understand its evolution over time. Let us start from the area where we find the Curia Julia.

 

Figure 1: The Roman Forum in a Google Earth image

 

Figure 2: Layout of the Curia Hostilia, Comitium and Rostra with Lapis Niger, in a work by Amadscientist for Wikipedia.

 

This Curia, also known as the Senate House, is a remarkable building. Its construction started in 44 BC, when Julius Caesar replaced the Curia Cornelia, which itself had replaced the Curia Hostilia, the original senate house of the Roman Republic (as told in [2], this “first Curia may have held historic significance as the location of an Etruscan mundus and altar”). Ref.3 explains the following about the building of the Curia Julia: "Caesar did so to redesign both spaces within the Comitium and the Roman forum. The alterations within the Comitium reduced the prominence of the senate and cleared the original space".  The Caesar's assassination interrupted the works that were finished by Caesar's successor, Augustus, in 29 BC [3,4]. The Curia Julia survives mostly intact, because it was used as a church, the basilica of Sant'Adriano al Foro, and had several later restorations. The roof and the upper elevations of the sidewalls are modern restorations. 

 

In the Figure 2, we can see a map showing how the Curia evolved. Let us note that the Curia Hostilia had an alignment along the cardinal north-south direction, that is, along the “axis mundi”, the axis about which the world seems rotate. Such astronomical alignment was in agreement to the religious Etruscan Doctrine inherited by the Romans [5,6], a discipline that imagined a “templum”, that is a sacred space, as a local representation of sky and Heaven. As previously mentioned, it seems that the Curia Hostilia was also the place of the “mundus”. This is another element of the Etruscan ritual [7]; the mundus was a pit imagined as a portal between the upper and the underworld.

As we can see from the Figure 2, the Curia Julia has a different alignment. Let us investigate if it has an astronomical alignment too. For this analysis, we use the approach proposed in some previous papers, by means of which we have seen how the Romans followed the Etruscan Discipline, using astronomical orientations for some of their towns. We have towns oriented to the cardinal directions, and towns having their main streets, the decumani, aligned along the rising of sun and moon on solstices and major lunar standstills [8-14]. In these references, the astronomical orientation was evidenced by using some modern ephemeris software, which is giving the sunrise/sunset and moonrise/moonset azimuths on satellite maps.

A well-known example of such modern ephemeris is the Photographer’s Ephemeris software. Let us apply it to the Curia Julia. The result is given in the Figure 3. We can see that the building is aligned along the northern moonrise azimuth on a year of major lunar standstill [15]. And then, this direction is also the norther possible azimuth we can have for moonrise at the latitude of Rome.

 

 

 

Figure 3: Snapshot of the Photographer’s Ephemeris, applied to the Curia Julia. In the image, the blue lines represent the northern moonrise/moonset directions on a major lunar standstill (April 2025). The yellow and orange lines are the sunrise and sunset azimuths.

 

Figure 4: Snapshot of the Photographer’s Ephemeris. In the image, the blue lines represent the northern moonrise/moonset directions on a year close to a year of major lunar standstill (February 2024).

 

The Curia Julia was founded in 44 BC. Let us investigate the possibility that this year was a year of major lunar standstill. As we did in [12] for the Roman town of Augusta Emerita, using CalSky, a web based astronomical calculator used by astronomers, we find that, for 44 BC, the maximum declination of the moon was of 28°30’ and, for 43 BC, the maximum declination was of 28°55’ degrees. It means that 44 BC was close to 43 BC, a year of major lunar standstill. Therefore, for what concerns the northern moonrise azimuth, on these two years it happened as on 2024 and 2025: we simulated the two cases in the Figures 3 and 4. It is evident that the moonrise azimuth is almost the same.

The coincidence of the date of the foundation of Curia Julia (44 BC) to a period of major lunar standstill reinforces the possibility that the building was planned, deliberately, with this specific astronomical orientation. Let us stress that Caesar, besides appreciating the works of Alexandrian astronomers and scholars, “was himself an astronomy enthusiast” [16]. He reformed the lunisolar Roman calendar, and even wrote several books on astronomy, as Pliny tells in his Naturalis Historia.

Besides the Curia, the Roman Forum is rich of several other monuments. From the Figures 3 and 4, we can see that the near church of Santi Luca e Martina has the same orientation of the Curia, but the Arch of Septimius Severus has a different orientation. It is a white marble triumphal arch dedicated in AD 203 for the commemoration of the victories of Emperor Septimius Severus and his two sons, Caracalla and Geta, during the wars against the Parthians.

In the Figure 5, we can see the Photographer’s Ephemeris applied to this monument. The arch seems aligned along sunrise/sunset on solstices.  It is possible that, during the imperial period, a processional route existed for triumphs that was passing below the arch, symbolically linking the emperor to the sun.

Another interesting complex having a possible astronomical orientation is the House of the Vestals. It was the residence of the Vestal Virgins, located behind the Temple of Vesta at the eastern edge of the Roman Forum. The Figure 6 shows us an orientation of it coincident to the northern possible moonset direction - which is also the southern possible moonrise direction - on a minor lunar standstill. In fact, the House of Vestals is aligned along one of the main axes of the Forum. This fact suggests that further astronomical investigations are necessary, about the original orientation of the oldest structures of the site.

 

 

 Figure 5: Snapshot of the Photographer’s Ephemeris, applied to the arch of Septimius Severus. Note the sunset direction on the summer solstice (which is also the sunrise direction on the winter solstice). It seems that the monument was deliberately aligned along such astronomical direction.

Figure 6: Snapshot of the Photographer’s Ephemeris, applied to the House of vestals. In the image, the blue line shows the site aligned along the northern moonset on a minor lunar standstill (October 2015).

 

References

[1] Vv. Aa. (2016). https://en.wikipedia.org/wiki/Roman_Forum

[2] Vv. Aa. (2016). https://en.wikipedia.org/wiki/Curia_Hostilia

[3] Vv. Aa. (2016). https://en.wikipedia.org/wiki/Curia_Julia 

[4] Claridge, Amanda (1998). Rome. An Oxford Archaeological Guide. New York: Oxford University Press.

[5] M. Pallottino (1975). The Etruscans, Bloomington & London, Indiana University Press.

[6] M. Pallottino (1955). The Etruscans, Harmondsworth, pp. 154-177; reported in The Religion of the Etruscans, according to Massimo Pallottino (2005), www.ancientworlds.net/ aw/Article/643090

[7] Milani, C. (2014). Varia Linguistica. EDUCatt - Ente per il diritto allo studio universitario dell'Università Cattolica.

[8] Sparavigna, A. C. (2014). Solstices at the Hardknott Roman Fort. PHILICA Article number 549. Available at SSRN: http://ssrn.com/abstract=2745184

[9] Sparavigna, A. C. (2016). The Town Planning of Pompeii and Herculaneum Having Streets Aligned Along Sunrise on Summer Solstice. SSRN Electronic Journal June 30, 2016). DOI: 10.2139/ssrn.2802439

[10] Sparavigna, A. C. (2016). Roman Towns Oriented to Sunrise and Sunset on Solstices. SSRN Journal May 8, 2016. DOI: 10.2139/ssrn.2777118

[11] Sparavigna, A. C. (2016). On the Orientation of the Roman Grumentum. SSRN Journal. DOI: 10.2139/ssen.2796722

[12] Sparavigna, A. (2016). Augusta Emerita and the Major Lunar Standstill of 24 BC. PHILICA Article number 635.

[13] Sparavigna, A. C. (2016). Alcuni siti romani in Piemonte orientati coi lunistizi. PHILICA Article number 604.

[14] Sparavigna, A. C. (2016). Torino e i Lunistizi. PHILICA Article number 603.

[15] The moon has an apparent behaviour, which is more complex than that of the sun. We have that the sunrise direction oscillates between the two solstice positions during a year, whereas the moon does the same during a nodal period (about 27 days). Moreover, the moon has a period – the lunar standstill period (18.613 years) – on which the values of the extremal directions (standstills) are changing. In this manner, there are major and minor standstills, of which we can calculate the directions that are depending on latitude. For a latitude of about 45°, like that of Torino for instance, we have that the minor and major northern moonrise azimuths (directions) are 47.40° and 65.65° (angles are given from true north). The minor and major southern moonrise azimuths are 116.35° and 132.58°. The azimuths of sunrise on summer and winter solstices are between these lunar azimuths. For the calculation of moonrise azimuths, we can sue the formula given by Jürgen Giesen at his web site http://www.geoastro.de/sunmoonpolar/index.html#Mondwenden. The reader can find detailed discussion and apps for simulate the moon apparent motion there.

[16] Moatti, C., Schofield, M. (2015). The Birth of Critical Thinking in Republican Rome. Cambridge University Press.




Information about this Article
This Article has not yet been peer-reviewed
This Article was published on 19th July, 2016 at 12:10:09 and has been viewed 1236 times.

Creative Commons License
This work is licensed under a Creative Commons Attribution 2.5 License.
The full citation for this Article is:
Sparavigna, A. (2016). A Possible Astronomical Orientation of the Curia Julia in the Forum of Rome. PHILICA.COM Article number 639.


<< Go back Review this ArticlePrinter-friendlyReport this Article



Website copyright © 2006-07 Philica; authors retain the rights to their work under this Creative Commons License and reviews are copyleft under the GNU free documentation license.
Using this site indicates acceptance of our Terms and Conditions.

This page was generated in 0.3442 seconds.