Astronomers are exploring what might be described as the first astronomical observing tool, potentially used by prehistoric humans 6,000 years ago. They suggest that the long, narrow entrance passages to ancient stone, or ‘megalithic’, tombs may have enhanced what early human cultures could see in the night sky, an effect that could have been interpreted as the ancestors granting special power to the initiated. The project targets how the human eye, without the aid of any telescopic device, can see stars given sky brightness and colour. The team intend to apply these ideas to the case of passage graves, such as the 6,000 year old Seven-Stone Antas in central Portugal. The team present their study at the National Astronomy Meeting, being held this week in Nottingham.
— source Royal Astronomical Society | 2016