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Dec 6, 2023
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NAME & USERNAME:
SECTION:
LAB 7
MAYA AND THE WANDERING STARS, I
INTRODUCTION
The Maya people created extensive records of the planet Venus— identified with the feathered serpent god Quetzacoatl. In particular,
references to the
584 days of synodic period of Venus
are found in Maya carvings and codices. The synodic period refers to the length
of time it takes for a planet, in this case Venus, to return to the same place in the sky as viewed from Earth.
In Maya records, the
synodic period is divided into four parts with lengths measured to be 8, 236, 90 and 250 days,
corresponding to different relative
positions of Venus and the Sun in the sky.
1
In this lab, we will use the Stellarium Web to visualize the motion of planets through Earth’s sky in order to better understand Maya
observations of Venus. You will learn how the periods of time recorded by Maya astronomers correspond to the various parts of Venus’s
orbit as viewed from Earth. You will then learn about the motion of Mars through the sky and how it differs from the motion of Venus.
You will continue to examine some Maya astronomical records and numerals in the next lab.
LEARNING GOALS
The point below is the expected topics to understand by the end of this lab period. Remember to review these points before completing
the lab. If you do not understand one, review the steps that cover it and discuss with your instructor.
Explore the different ways planets can move through the sky as viewed from Earth
We will be making use of the
Stellarium Web
(stellarium-web.org
, recall Lab 1).
In the following, all instructions are based on
Stellarium Web.
You can also choose to download and install Stellarium. For most platforms, Stellarium is free to download, but if you
have trouble accessing the software, Stellarium is installed on the computers in the computer lab as well— ask your instructor for more
help. Note that the setup and buttons are different from the Web version.
1
1
You can also watch the Maya Myth of the Morning Star, by Ted-Ed: https://www.youtube.com/watch?v=Z2vzrQWny_c
LAB7-1
NAME & USERNAME:
SECTION:
STEP 1: THE MOTION OF VENUS
To understand how the Maya records work, we will use the Stellarium Web to visualize the motion of Venus in the sky throughout its
synodic period. Now let's open
Stellarium Web
and explore this technique. Click on the bottom left box to change the location to
Yucatan, Mexico
, and then click on the
Date and Time
box at the bottom right corner to bring up the interactive menu.
1.
Manually change the date to
October 19th, 1273,
by clicking on the arrows below and above the dates. Click the small pause button
to stop the time from advancing and change the time around
15:45
in the afternoon (in Flagstaff time).
Again, this time might seem
strange, but it is due to Stellarium’s default setting of your local time zone. We can ignore the time for now!
Move your sky
around until you find Venus. Where is Venus relative to the Sun? Draw a picture of what you observed of the Sun and Venus below.
[0.5pt]
Step through one day at a time for 8 days until
October 27th, 1273
and observe how the position of Venus changed at the same time
relative to the Sun. Notice how at this date you cannot see Venus in the evening since the Sun is still up in the sky. Manually change
the time to
4:30 am
Flagstaff time
instead and find where Venus is in the sky now. Which direction is Venus moving relative to the
Sun? Draw a picture of what you observed now of the Sun and Venus below.
[0.5pt]
1.
Between October 19th and 27th, Venus is actually invisible because it sets before the Sun and rises too close to the Sun. Starting
around Oct 27th, Venus is far enough from the Sun that it can be seen in the early morning again. After this day, Venus is visible in
early morning for 236 more days. What date is 236 days after October 27th, 1273?
Manually change the date to this date and find a time that you can still see Venus before sunrise. Where is Venus relative to the Sun
now? Draw a picture of what you observed now of the Sun and Venus below.
[0.5pt]
LAB7-2
NAME & USERNAME:
SECTION:
Step through one day at a time for another 7 days, and observe how the position of Venus changed at the same time relative to the
Sun. Which direction is Venus moving relative to the Sun? Draw a picture of what you observed now of the Sun and Venus below.
[0.5pt]
Between the two dates in parts 1 and 2, is Venus visible in the evening, or in the morning?
2.
For the next 90 days, Venus moves too close to the Sun and the Maya reckon that Venus is no longer visible as it moves behind the
Sun as seen from Earth. What date is 90 days after the date you calculated in part 2?
Manually change the date to this date. Notice again how at this date you cannot see Venus in the morning since the Sun rises before
Venus. Manually change the time to
16:15 Flagstaff time
instead and find where Venus is in the sky now. Where is Venus relative to
the Sun now? Draw a picture of what you observed now of the Sun and Venus below.
[0.5pt]
Step through one day at a time for another 7 days, and observe how the position of Venus changed at the same time relative to the
Sun. Which direction is Venus moving relative to the Sun? Draw a picture of what you observed now of the Sun and Venus.
[0.5pt]
LAB7-3
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NAME & USERNAME:
SECTION:
3.
Venus is visible during this time of day for 250 more days. What date is 250 days after the date you calculated in part 3?
Manually change the date to this date. Slide the time until the Sun is about to set, at around
17:00 Flagstaff time
. Where is Venus
relative to the Sun now? Draw a picture of what you observed now of the Sun and Venus. (Note you can turn off the Landscape if it
helps.)
[0.5pt]
Step through one day at a time for another 7 days and observe how the position of Venus changed at the same time relative to the
Sun. Note you may also have to change the time as well. Which direction is Venus moving relative to the Sun? Draw a picture of
what you observed now of the Sun and Venus.
[0.5pt]
Between the two dates in parts 3 and 4, is Venus visible in the morning or in the evening?
4.
For the next 8 days, the Maya reckon that Venus is no longer visible as it moves in front of the Sun as seen from Earth, after which
the synodic cycle of Venus starts over. What date is 8 days after the date you calculated in part 4?
Between this date and the date you calculated in part 4, a special astronomical event occurs that may have been visible to the Maya.
What is this event, and on what date did it occur?
STEP 2: SYNODIC PERIOD OF VENUS
LAB7-4
NAME & USERNAME:
SECTION:
Let’s summarize the Synodic Period of Venus that Maya carefully observed and recorded in the table below from Step 1.
[5pts]
Length of Days
Dates
Is Venus visible
in the sky?
Is Venus a morning star
or an evening star?
Draw a picture depicting the motion of Venus
during this length of days.
8 days
236 days
90 days
250 days
LAB7-5
NAME & USERNAME:
SECTION:
STEP 3: THE RETROGRADE MOTION OF MARS
As you may have noticed in the last step, Venus stays fairly close to the Sun as it moves through the sky. This is because the orbit of
Venus is closer to the Sun than the Earth’s, so to see Venus, we must always be looking inwards, towards the Sun. On the other hand,
planets that are further away from the Sun than the Earth (Mars, Jupiter, Saturn, etc) follow different paths through the sky. One type of
motion these planets can go through is
retrograde motion,
which occurs when the Earth “catches up” to the planet in its orbit, causing it
to appear to move backwards relative to the background stars.
On the star chart below, plot the position of Mars for the following dates (use Stellarium for preview). Connect the plotted positions
according to the dates with a line, and indicate the general direction of motion using an arrow.
[1pt]
LAB7-6
-10°
17h
15h
0°
-20°
-30°
16h
ORPHIUCHUS
SCORPIUS
LIBRA
VIRGO
LUPUS
Antares
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NAME & USERNAME:
SECTION:
Dates:
2/22/2016
4/25/2016
6/27/2016
2/29/2016
5/2/2016
7/4/2016
3/7/2016
5/9/2016
7/11/2016
3/14/2016
5/16/2016
7/18/2016
3/21/2016
5/23/2016
7/25/2016
3/28/2016
5/30/2016
8/1/2016
4/4/2016
6/6/2016
8/8/2016
4/11/2016
6/13/2016
8/15/2016
4/18/2016
6/20/2016
8/22/2016
LAB7-7