Tombs can be found in Spain and Scandinavia, as well as within the United Kingdom. 'They were clearly a widespread phenomena spanning the entire Atlantic coast,' Silva and Brown said by email.

Famous examples include Ireland's Newgrange and Scotland's Maeshowe. According to Silva and Brown, most passageways date back to the Neolithic period, between 6,000 and 2,000 B.C., though some show continued use during the Bronze Age. Some of the tombs feature paintings or engravings tied to their original use. The early tombs consisted of single or multiple chambers with a corridor leading to an entrance, and the entire structure was covered with mounds of earth or stone. Revealing Secrets Ancient cultures across Europe placed their dead within passage graves. Silva) 'By reducing the background area and focusing on just a small part of the sky, an observer will be able to see a star earlier than had they been outside,' Simcox said. He presented the results Thursday at the National Astronomy Meeting in England.ДЄ view of several ancient passage graves.a) Dolmen da Orca in Western Iberia, b) the window of visibility from within the the chamber, c) Orca de Santo Tisco in Portugal. Led by Daniel Brown, also of Nottingham Trent, and Fabio Silva, of the University of Wales Trinity Saint David, Simcox studied passage graves' potential as astronomical instruments. 'By using these passage graves, the observer would have sat in complete darkness, with only the opening to the passage grave in front of them showing the part of the sky where the star rises,' Kieran Simcox, an undergraduate student at Nottingham Trent University in England, told Discover by email. The extended narrow entrances of the graves, which are scattered across Europe, may have amplified a viewer's night vision, allowing them to detect stars rising at twilight sooner than they would otherwise be able to. New research suggests that prehistoric humans may have relied on long dark chambers in igloo-shaped structures known as 'passage graves' to see the rising stars.

(Credit: Vector99/Shutterstock) Ancient astronomers may have used tombs to probe the heavens. Ancient graves like Dolmen Pedra da Orca in Gouveia, Portugal may have also enhanced the view of stars.

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