London: Ancient megalithic tombs found in Europe could be the first astronomical observing tools used to watch skies by humans 6,000 years ago before the invention of telescopes, according to scientists.
The long, narrow entrance passages to these prehistoric tombs enhanced the night sky.
According to the team's analysis, the narrow entrances of so-called passage graves can increase the visibility of specific stars to the human eye.
The passage grave would have kept stargazers cloaked in darkness save for its narrow opening, which would make stars in that field more visible.
They focus this study on passage graves, which are a type of megalithic tomb composed of a chamber of large interlocking stones and a long narrow entrance.
These spaces 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 lined with the remains of the tribe's ancestors.
These structures could therefore have been the first astronomical tools to support the watching of the skies.
"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," said Kieran Simcox, a student at Nottingham Trent University in the UK.
The project targets how the human eye, without the aid of any telescopic device, can see stars given sky brightness and colour.
The team intends to apply these ideas to the case of passage graves, such as the 6,000-year-old Seven-Stone Antas in central Portugal.
"The orientations of the tombs may be in alignment with Aldebaran, the brightest star in the constellation of Taurus.
To accurately time the first appearance of this star in the season, it is vital to be able to detect stars during twilight," said Fabio Silva, of the University of Wales Trinity Saint David in the UK.
The first sighting in the year of a star after its long absence from the night sky might have been used as a seasonal marker, and could indicate for example the start of a migration to summer grazing grounds.
The timing of this could have been seen as secret knowledge or foresight, only obtained after a night spent in contact with the ancestors in the depths of a passage grave, since the star may not have been observable from outside.
However, the team suggests it could actually have been the result of the ability of the human eye to spot stars in such twilight conditions, given the small entrance passages of the tombs.
(With Agency inputs)
