COURTESY OF David Levy
The El Caracol observatory in Chichen Itza looks like its dome could house a telescope, but it just provided a space for viewing ports.
Mayans kept a close eye on Mars
Have you ever taken a voyage
A David
through time? Have you had a chance
Levy Sky
to visit an earlier time and place? I
hope that you will have the chance
someday to visit Chichen Itza. This
issue of Sky’s Up is about Mars — a
planet of wonder and mystery. And
in this article, I want to provide some
insight about how an ancient culture
from more than a thousand years ago
observed Mars.
by David
We arrived at the city of Chichen Itza
Levy
on the afternoon of Feb. 16, 2018.
The site was jammed with tourists and
people wanting to sell crazy souvenirs, but none of
that took away from the idea that here was a visit to a
distant and all-but-forgotten time.
The observatory, El Caracol, was not visible from
the front entrance. But when we walked down a trail
through shrubbery, we encountered it — the largest
structure in all of Chichen Itza. Larger in area than
the two pyramids, larger in area even than the sports
stadium, El Caracol faces the sky with the questions,
answers and ideas of a great civilization.
All of this brings us to the theme of this issue of
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Sky’s Up — the planet Mars. The planet has an
extraordinary history, but what many readers might
not be aware of is how far back humanity’s fascination
with the planet goes. That story goes back at least
as far as the Mayan civilization. More than 1,300
years ago, men, women and children were looking
at the sky from there. They were asking questions
like we do and wondering. If these people from long
ago lived at Chichen Itza then they knew about an
observatory building there. Although we know that
this observatory specialized in Venus, it also was set
up to study Mars.
El Caracol was built no later than 900 AD, more than
1,100 years ago, and long before that the people were
looking at the sky. The observatory provided a way
for the Mayan people to observe changes in the sky.
By climbing the steps and looking through viewing
portals, observers could view the sky above the dense
local vegetation.
Mayan astronomers were excellent record keepers.
Their records were necessary to develop and to perfect
their solar calendar, which consisted of 360 days
plus five extra days set aside for celebrations. But I
imagine an additional reason for their records. These
Mayan astronomers believed that writing things down
Sky ’ s
Up
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.
COURTESY OF David Levy
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
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