(Dolmen da Orca, one of a cluster of stone tombs in Carregal do Sal, Portugal, may have helped people track star movements thousands of years ago. Credit: F. Silva)
I read an article entitled, Tomb with a View: Ancient Burial Sites Served as ‘Telescopes’, on Live Science’s website. In the article, author, Mindy Weisberger, talks about the how tombs served another purpose in ancient times. It is believed that stone tombs were used to view the sky and the stars.
(View of the Dolmen da Orca passage and entrance while standing within the tomb’s chamber, looking toward the “window of visibility.” Credit: F. Silva)
According to the author, these ancients stones served as some of the earliest telescopes without lenses. The type of tombs studied by the researchers mentioned in the article are passage graves. The researchers studied these types of graves because of their long, narrow tunnels which intensify the view of faint stars. Researchers also studied passage graves because “the orientation of some passage graves is known to align with the positions of certain stars.” After the author introduced the reader to passage graves, she went on to mention that passage graves were considered to be sacred. And, depending on their location, the architectural style may have been different but based on similar themes.
The author continued in the article by addressing the size of the entrance of the tombs being used as a viewing device. According to Daniel Brown, a senior lecturer in astronomy quoted in the article, the entrance to passage graves “creates an aperture as large as ten degrees through which your naked-eye view is restricted.” Brown went on to mention that this particular view makes it easier to view the sky during dawn and dusk because of the lack of light in the tomb. The eyes become adjusted and then able to see the sky at a lower light level.
The passage graves are a very basic almost archaic form or beginning for a telescope. However, the design of passage graves reminds me of the refracting telescope if for no other reason than the measurement of the aperture and the long, narrow tunnel design. We know that the telescopes of today have lenses to help focus light which is much of what applies to the work of a refracting telescope. Most of the refracting telescopes I have viewed have an average aperture of about 3-4″ which is about 10 degrees wide. So, I felt that the passage graves were a small beginning into the development of the refracting telescope. Now, of course, we know that passage graves did not have lenses. The only lens present for viewing through the tomb was that of the actual eye so there were limits as with any telescope.
The reflecting telescope pulls in light through the use of mirrors. One of the advantages of using a reflecting telescope that we discussed in class was the fact that it is very good when viewing dim objects. The author, Mindy Weisberger, mentioned that the passage graves made it easier to view the sky during dusk and dawn because of the lack of light in the tomb and the small passage way. The author also mentioned that the natural light that passed through the small opening allowed viewers to see faint stars. The passage grave in this aspect took on an advantage that we see in the reflecting telescopes.
I can’t say that I saw any similarities between the passage graves and the radio telescopes other than the fact that both receive visible light. But, radio telescopes read radio emissions which are mainly visible in the radio region of the electromagnetic spectrum. However, thinking about radio waves and visible light did remind me of the lecture tutorial that we worked on entitled, “Telescopes and Earth’s Atmosphere” (pictured below). In the tutorial, we learned about different wavelengths and how they penetrate the Earth’s atmosphere, if at all. As shown below, the visible light and radio waves both completely penetrate Earth’s atmosphere and reach the surface.
Obviously, we know that graves and tombs could not be placed in the sky. However, the telescopes we work with today can. But, the wavelengths the telescopes are set to help study and view don’t all penetrate the Earth’s surface. In these cases, we need to place the proper telescope above the Earth’s atmosphere to study, view, or measure wavelengths.
When I began to read the article, I must admit that I thought I wouldn’t be able to find any similarities between the passage graves and the telescopes of today. But, I am glad to say that I was wrong. It is very interesting how technology in how we view the sky has come such a long way. But, it is also nice to know that practices from ancient times can still provide us with a great view of the sky.