added permanence to what they were seeing . If they didn ’ t write things down , they hadn ’ t completed their observations . Sometimes their records were fortunate enough to form part of the Mayan official codices that charted the positions of the planets — including Mars . The Mayans learned how Mars orbited on a period of about 780 days , or more than two Earth years . The Mayan culture knew about these cycles and paid close attention to them . If they didn ’ t , then our own civilization would have a far more limited knowledge of the motions of the planets and we would probably not be able to send spacecraft to them . Instead , we have several spacecraft still roving about Mars right now , finding out things about which we never could have imagined . One thing the Mayans calculated was the synodic period of Mars . It is defined as the time required for Mars to return to about the same location in the sky relative to the Sun as seen by an observer on the Earth . It involves the time needed for the Earth to overtake Mars as both go around the Sun . Mars ’ s synodic period , we now know , is 686.98 days . The Dresden codex , one of the central headquarters of Mayan records , shows a Mars table of 702-day intervals that
is close to their understanding of the motions of Mars . The Mayans might have enjoyed this issue of Sky ’ s Up , with all the information about Mars itself that they had no access to . They were interested in Mars ’ s changing positions in the sky , and not in its physical appearance . They couldn ’ t be , because all they could see was a bright point in the sky , a light that moved among the stars over time . The reason they could never really see Mars is that they had no telescope . But they did keep incredibly good records on where Mars was in the sky at any given time . Because of that , we now enjoy seeing Mars close-up , either with a telescope from our back yards or using a camera attached to a spacecraft that sits directly on the planet ’ s surface . In this issue of Sky ’ s Up you will get a sense of what we now know about Mars , from the understanding passed on to us by the ancient Mayan astronomers at their El Caracol observatory all the way to the latest images of a rock sitting in the Martian Sun . This issue shows that despite all we have learned over the eons , in important ways we haven ’ t changed much . Mars is still there . It is still mysterious and , more than ever , it beckons our curiosity and our wonder .
The largest structure at Chichen Itza is El Castillo , the major pyramid .
Over decades of observing , David Levy has discovered or co-discovered a total of 23 comets . His prolific record includes the joint discovery of Shoemaker-Levy 9 , which quickly went on to dramatically crash into Jupiter in 1994 , and the individual discoveries of two periodic comets – P / 1991 L3 and P / 2006T1 – through his backyard telescope . In 2010 , Levy became the first person to have discovered comets in three ways - visually , photographically and electronically . Beyond his observation achievements , Levy has authored , edited or contributed to more than 30 books and has periodically provided articles for publications like Sky & Telescope and Parade Magazine .
Sky ’ s Up
COURTESY OF David Levy
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