In a recent study, astronomers believe that they may have found out the first stargazing tool known as Ancient megalithic tombs used to watch the skies.

The 6,000-year old Seven-Stone Antas in Portugal may have been the first of its kind tool to be used by prehistoric humans.

The team idea through this study was to find out how narrow entrance passages to ancient stone could make it possible for the human cultures to see the night sky.

The researchers also further investigated how single opening or doorway made it possible for human during that time to observe the fainter stars.

The team which also consisted of researchers from Nottingham Trent University focused their study on the passage graves megalithic tomb which was built in the fashion of large interlocking stones and had a long narrow entrance.

This sites were known to be sacred and has been constructed to allow the presence of natural light. It was built for the initiate who would spend the night inside the tomb.

Therefore the structure of the tomb might have been the first astronomical tools even before the telescope was invented to watch the sky. The team in their research also wanted to study how human eye without any help from the telescope was able to explore the sky and stars.

The star sighting during that time may also be a seasonal marker so that people during this period could start their migration to summer grazing grounds. The timing for star gazing may have been sacred as it was only possible to study the sky in the depths of passage grave since it was not feasible to study it from outside.

Also, when researchers studied the 6,000-year-old Seven Stone Antas in central Portugal, it was found out that the tomb was built in alignment with Aldebaran known as the brightest star in the constellation of Taurus.

The study is to be presented at the National Astronomy Meeting this week at Nottingham will also dwell on the fact that because of the small entrance passages of the tombs the human eye developed the ability to spot stars in even twilight conditions.