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Neolithic tombs were telescopes to view the stars
Megalithic tombs could have been early telescopes which prehistoric communities used to set their calendar thousands of years before Galileo, scientists have proposed.
Astronomers believe that the impressive passage graves of the Neolithic provided a unique window from which to view the stars with unprecedented clarity.
Researchers at Nottingham Trent University and the University of Wales Trinity Saint David suggest that standing at the centre of pitch black tomb, and looking out through the entrance, would have allowed even faint stars to become visible.
The team is currently studying 6,000-year-old graves in Carregal do Sal, Portugal, where 13 passage graves are thought to be aligned with Aldebaran, the brightest star in the constellation Taurus.
Dr Fabio Silva, a lecturer in Skyscapes, Cosmology and Archaeology at the University of Wales, believes the appearance of Alderbaran signalled the start of the summer migration.
“To accurately time the first appearance of this star in the season, it is vital to be able to detect stars during twilight,” said Dr Silva.
“Studies have confirmed that the vast majority of passage graves in Portugal are oriented in such a way as to align with two or three stars, the most important of which was Aldebaran
“It is possible that more passage graves, throughout Europe and the UK, also align to bright stars, possibly even Aldebaran. The star rising would have had a particularly important meaning for these communities.
“Rock art and paintings, some of which are present inside similar passage graves, could and have been interpreted as red stars, much like Aldebaran itself.” At the time of construction, around 4,300–3,700 BC, Aldebaran would have risen exactly within the band of the horizon that is visible from within all of the entrance passages of tombs at Carregal do Sal between 18–27th of April.
The star would have been invisible in the previous months and, upon its arrival, Neolithic communities would have moved their cattle on to the higher pastures of nearby Serra da Estrela.
Passage graves, are a type of megalithic tomb composed of a chamber of large interlocking stones, reached by a long narrow entrance.
The burial chambers are thought to have been sacred, and the sites may have been used for rites of passage, where the initiate would spend the night inside the tomb, with no natural light apart from that shining down the narrow entrance, which was lined with the remains of the tribe's ancestors.
It is possible the Neolithic people believed that the star Aldebaran protected their ancestors or was the heavenly abode of the dead, according to the researchers.
As well as an ossuary, the aperture of the tomb entrance would also have provided the first astronomical tools to monitor the skies, millennia before telescopes were invented
Dr Silva added: “A good proportion of archaeologists and anthropologists have ignored the sky for too long, but the communities that built these prehistoric structures would have lived under dark skies and would have been inspired by it.”
Keiran Simcox, a student at Nottingham Trent University added: "It is quite a surprise that no one has thoroughly investigated how for example the colour of the night sky impacts on what can be seen with the naked eye.”
Timothy Darvill, Professor of Archaeology at Bournemouth University, said: “There are more than a thousand passage graves along the Atlantic coastlands of northwest Europe. How they were used has been a question on the lips of many archaeologists for centuries.
“Some, including the well-known examples at Newgrange in Ireland and Bryn-celli-Ddu on Anglesey, seem to have been orientated towards either the sunrise or sunset on the summer or winter solstice.
“But only about 10 per cent of passage graves seem to have these orientations. It would be wonderful if the proposed research could identify patterns that apply to the other 90 per cent.”
The research is being presented at the National Astronomy Meeting in Nottingham.