The autumnal equinox from the Dolmen of Magacela

El tholos de Cerro de la Barca, a la orilla del embalse García de Sola, se encuentra en el municipio de Valdecaballeros (Badajoz, Extremadura). En la imagen, sobre este monumento megalítico, la Vía Láctea (izquierda) y las Pléyades (centro). D. Padrón.
Advertised on

Next Friday, September 23nd, at 01:04 UT the Earth will be at a specific point in its orbit round the Sun: the September equinox. The September and March equinoxes are the only days in the year when the Sun rises exactly in the east and sets exactly in the west, across the whole planet. In practical terms the days at both the vernal and the autumnal equinoxes are divided equally into daytime and night-time, with each lasting approximately 12 hours. In fact the literal meaning of the word equinox, is “equal night” and comes from the latin word aequinoctium.

Live from the Dolmen of Magacela

The dolmens are megalithic funeral monuments built mainly between 4000 and 2500 years B.C. In the particular case of the Dolmen of Magacela, in the region of La Serena, it has a circular chamber, similar to that of the tholos at Cerro de la Barca, about 5 metres in diameter, delimited by 12 granite orthostats and, although it is not preserved at present, research indicates the existence of an entrance corridor, about 9 metres long.

Thanks to research by archaeoastronomers such as Michael Hoskin, Juan Antonio Belmonte and Cesar González García, who have studied the orientation of megalithic tombs in Spain and Portugal, we know that these dolmens are oriented in a fairly coherent way. The majority point towards the East on the horizons of the different geographical areas analyzed. To be specific they point towards the sector of the horizon from which the Sun and the Moon rise, and some of the orientations coincide with dates close to the equinoxes, dates which mark changes of the seasons, and in the case of the autumnal equinox in Extremadura, mark the beginning of the rainy season.

Alineación al amanecer

The channel will offer a live transmission of the sunrise, working within the Energy Efficiency Laboratories project (EELabs), and with the collaboration of the Office of the Director General of Tourism of the Junta of Extremadura and the project Extremadura Buenas Noches, from the Dolmen of Valdecaballeros (Extremadura).

The date is next Friday, 23rd September at 06:30 UT (07:30 local time in the Canaries, 08:30 Central European Standard Time). Sunrise will happen at 08:16 local time. 

"The vernal and autumnal equinoxes are the geometrical points in the Earth’s orbit around the Sun when a line from the centre of the Sun lies in the equatorial plane of the Earth. The people who live at the equator will see the Sun exactly overhead at local mid-day”, comments Miquel Serra-Ricart, an astronomer at the IAC, who is in charge of the broadcast.

Workshop: Cielos de Extremadura

To coincide with the broadcasting of the equinox, on 23rd September, the Workshops: Cielos de Extremadura will take place, which are held annually at the Escuela de Hostelería in Mérida, organised by Extremadura Buenas noches and aimed at those people who want to enter the Star Tourism sector.

EELabs ( is a project funded by the Programme INTERREG V-A MAC 2014-2020, cofinanced by FEDER (European Fund for Regional Development) of the European Union, under contract number MAC2/4.6d/238. Five centres in Macaronesia (IAC, ITER, ULPGC, SPEA-Azores and SPEA-Madeira) work in EELabs. The objective of EELabs is to build laboratories to measure the energy efficiency of the artificial night lighting in protected natural areas in Macaronesia (the Canaires, Madeira, and the Azores).

Extremadura Buenas Noches (Extremadura, Good Night) is a project within the Night Strategy of the Junta of Extremadura (Extremadura 2030).

Three Spanish Supercomputer centres: The Extremadura Centre for Advanced Technologies (CETA-CIEMAT), the Council of University Servers of Catalonia (CSUC) and the Instituto de Astrofísica de Canarias (IAC) are collaborating in distributing the broadcast of the web portal (

EELabs ( es un proyecto financiado por el Programa INTERREG V-A MAC 2014-2020, cofinanciado por el FEDER (Fondo Europeo de Desarrollo Regional) de la Unión Europea, bajo el contrato número MAC2/4.6d/238. En EELabs trabajan 5 centros de la Macaronesia (IAC, ITER, ULPGC, SPEA-Azores, SPEA-Madeira). El objetivo de EELabs es crear Laboratorios para medir la Eficiencia Energética de la Luz Artificial Nocturna en áreas naturales protegidas de la Macaronesia (Canarias, Madeira y Azores).

Extremadura Buenas Noches is a project included in the Night Strategy of the Junta de Extremadura (Extremadura 2030). Turismo de Extremadura collaborates in the activities.

Three Spanish Supercomputing centres: the Centro Extremeño de Tecnologías Avanzadas (CETA-CIEMAT), the Consorci de Serveis Universitaris de Catalunya (CSUC) and the Instituto de Astrofísica de Canarias (IAC) will collaborate in the distribution of the web portal (

Interesting links: