Lab-01_Zodiac1 (1)
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MISC
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Astronomy
Date
Dec 6, 2023
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THE ZODIAC & OTHER CONSTELLATIONS
Objectives
1.
Recognize the names and shapes of a few major constellations
2.
Explain the significance of the constellations of the zodiac.
3.
Recognize the names of some of the brightest stars visible from the northern hemisphere and the constellations in which they lie.
Marketable Skills:
This course assesses the following Core Objectives. In this assignment, you will develop the following marketable skills: Critical Thinking
Analyze Issues
Anticipate problems, solutions, and consequences.
Apply knowledge to make decisions
Detect patterns/themes/underlying principles
Interpret data and synthesize information
Communication
Summarize information
Use proper technical writing skills
Personal
Responsibility
Accept responsibility
Exhibit Time Management
Show attention to detail
Learn and grow from mistakes
Empirical Quantitative
Communicate results using tables, charts, graphs
Contextualize numeric information/data
Demonstrate logical thinking
Draw inferences from data, use data to formulate conclusions
Equipment
Stellarium software – a free download.
Go to the website: https://stellarium.org/
Download the version appropriate to your computer operating system. 1
The instructions for this lab have been written using Stellarium version 21.2
You may or may not need the following steps:
a)
Click on the correct operating system to download the correct version for your computer. If you have Windows, the correct file will be “For Windows.”
b)
The host site, Sourceforge.net, will send you to another site where you will be downloading Stellarium. Follow the directions as to where the file should be downloaded on your computer. We suggest you save the file to the computer desktop so you will be able to find the file to complete the installation process.
c)
Once the file has been downloaded, then “run” the file to complete the installation. As you run this file, just follow the onscreen instructions.
d)
If the installation does not create a desktop icon, you will need to go to your “Program Files” directory and find the Stellarium file. Right click on the file and choose “Send To” and then “Desktop.” This will create an icon on your desktop for the software.
e)
You can now delete the downloaded file from your desktop.
You will notice two Stellarium icons on your desktop. One is for the Install file (step you
did in c) and the other is for the Program file (step d). We recommend that you delete
the Install file and icon since you have completed the installation process. Your desktop
will now have only one Stellarium icon to run the program.
Introduction
A dark night sky sprinkled with stars both brilliant and bright, can be a spectacular sight.
Living in the city as we do, we have unfortunately lost this great natural resource. But
we have only to go a few miles out into the country to realize and relish the beautiful
sight of a night sky studded with thousands of pinpoints of light. The night sky enthralled
and entertained, and it was natural for people to wonder about the stars and notice how
2
they moved. Humanity has an innate desire to organize facts, to try and understand the
pattern and relate it to better-known events.
Even a child realizes the difference between night and day, and we have been taught
since grade school that this is due to the rotation of the earth on its axis. The sun and
the moon, as the most obvious objects in the sky, seem to follow a daily path that has its
own pattern. While the pattern for the sun and the moon are different, there are also
some distinct similarities between them. For one thing, they each travel along a path
that goes roughly from east to west. The path taken by the sun is known as the ecliptic
.
The exact position of the ecliptic in the sky depends on the calendar date and the
location of the observer. The moon shows a cycle of phases that repeats every month,
and since there are twelve lunar cycles in one solar cycle, we have our familiar calendar
of twelve months in a year.
But what about the pattern formed by the stars? Even the ancient people recognized
that stars seemed to move in groups. They noticed that some stars were only visible
during certain times of the year and recognizing them could help them predict the
changing seasons. They related the celestial happenings with events on earth, like the
flooding of the river or the onset of winter. To entertain themselves, they wove stories
around the strange shapes they saw in the sky. Some stars were so bright, they gave
them their own names, and some names have passed through many different
civilizations and are still in use. It was natural for the ancient people to weave stories
around the stars, relating neighboring shapes, and depicting cultural traditions and
morals. Each civilization has its interesting star tales, and you may want to read some of
them as you get familiar with the stars.
It is easily noticed that stars do not move in a random manner. Also, a group of stars
seems to form a family and move together. This group of stars is called a constellation
.
It was natural to relate the constellation shape and name to some easily recognizable
pattern. The ancient constellations are named after mythical heroes and heroines,
animals, and birds. Constellations in the southern hemisphere, which were recorded
after it was possible to travel vast distances by sea, have been given names that reflect
the technology of the times, like a compass and an hourglass.
In the 1920’s the International Astronomical Union divided the celestial sphere into 88
regions and named each region after the prominent constellation in it. In many cases
the constellation boundaries were drawn to fit the available well-known constellations.
Therefore, today when we talk of "Orion", we mean the easily recognizable star pattern
that you can see and the region surrounding this constellation.
The brightest stars have their own distinctive proper names
. (Some authors use the
term common name instead of proper name). Many of the proper names in use today
are of Arabic origin, and they signify some descriptive term for the star or its position in
the constellation. Since there are many other stars without proper names, astronomers
and catalogers have developed many different methods to name stars. The Bayer
3
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system formulated in the early 1600's uses Greek letters with the possessive form of the
constellation name. The first letter of the Greek alphabet, alpha (
) is used for the
brightest star, beta (
) for the next brightest, and so on. For example, the brightest star
in Scorpius has a proper name Antares, and its Bayer name is
-Scorpii (the alpha-star
belonging to Scorpius). The abbreviation for this is
Sco.
As the earth travels around the Sun, its night-time hemisphere faces different
constellations over the course of a year. Similarly, its daytime hemisphere, identified by
the location of the sun, is also facing different parts of the celestial sphere. Or, as
astronomers say, “the sun lies in different constellations over the course of a year.”
Since the sun is one of the most important naked-eye objects for us, it was natural for
ancient astronomers to assign a special significance to the constellations that “hosted”
the sun. Because of the twelve lunar cycles in one solar cycle, they identified twelve
constellation shapes that were particularly important. These twelve constellations are
called the zodiac
. In other words, the constellations that lie along the ecliptic form the
twelve constellations of the zodiac. However, these twelve constellations are not equal
in size. Some are much bigger than others, and some have been named even though
the pattern of stars is not obvious, but it was important to give the sun’s host area a
name! Remember that while the constellation boundaries have only been recently
drawn, the shapes and figures of the zodiac are very ancient; in some cases, they are
over 3,000 years old.
It is important for you to make a distinction between the astronomical constellations of
the zodiac and the astrological signs of the zodiac. The constellations are real
groupings of stars. However, to understand and foretell the future, people have
assigned a significance to the signs of the zodiac that has no place in today’s science.
While we can understand and appreciate the need of ancient people to look to the
heavens and relate celestial happenings to their daily life, today we have a much better
understanding of the way the universe works and our individual place in it.
In the 1600’s mathematicians like Johannes Kepler realized there had to be rules to
predict the movement of planets, and he worked tirelessly to determine them. Kepler,
with his superior mathematical skills, earned his living casting astrological charts. But
according to Owen Gingerich, he was “the astrologer who destroyed astrology.” Today
we remember Kepler for his three rules of planetary motion that allow us to accurately
predict the movement of any object around another.
There is another reason why the astrological signs or “sun signs” are not accurate. The
earth’s axis undergoes precession
, which means the axis traces out a cone in 26,000
years. In other words, the north pole does not point to the same section of the sky today
as it did 3,000 years ago. This means that the vernal equinox, the pole star, and the
sun’s location in the constellations have all changed! In fact, because of precession,
star maps are now redrawn every 50 years. One of the activities in this lab will be to
examine which constellations “host” the sun today compared to 3,000 years ago when
the astrological charts were developed.
4
Star charts are usually printed in a circle, with the center representing the “
zenith
” or
overhead point. Since we see the sky as a three-dimensional hemisphere but can only
print the star map on two-dimensional paper, we must hold the map above our head and
bend it like a cap to visualize the three-dimensional sky. These ideas will become clear
as you do this lab.
LAB EXERCISE
NOTE: Steps to do on the computer are in alpha-order (A, B, C, etc.) Questions to answer are in numeric order (1, 2, 3, etc.)
A.
You should have downloaded Stellarium from the web, using the instructions
shown under Equipment on page 1. Open Stellarium on your computer and keep
a hard copy of these instructions to follow directions and write your answers.
B.
Stellarium will open on today’s date and present time in Paris (since it is the
home of the developers). Take a few minutes to look at the screen. You should
see today’s date and time on the bottom of the screen.
C.
Move your mouse pointer down and to the left of the screen; two menu tool bars
should pop up. D.
If you look at the L SHAPE bracket in the corner, you should see two arrows one
facing up and one facing right. Click on both arrows, should change the arrows to
squares. I have changed the landscape to Ocean so that you can see the icons better.
5
E.
You will notice the nineteen icons at the bottom of the screen and six icons on the
left of the screen. Also, on the bottom are 5 icons for fast forward, reverse, play
and the on-off symbol. Click on each one of the bottom nineteen icons to see
what they do. For the first step, turn them all OFF, EXCEPT GROUND (6th from
left), ATMOSPHERE (7th from left), CARDINAL POINTS (8th from left) and FULL
SCREEN MODE (14th from left).
F.
Next let’s set the sky for Dallas as the default. To do this, click on the LOCATION
window (which is the uppermost icon in the vertical tool bar). Beside the
magnifying glass symbol in the Location window type “Dallas.” You will see 2
cities; choose Dallas (Texas) by clicking on it. Another way is to input Dallas’
exact longitude as 96º 48
W and latitude as 32º 46
N. Check “Use Current
Location as Default.” Also Check “Enable daylight saving time.” Click the X in top
right.
G.
Now we need to close Stellarium and re-open it for the changes to take effect.
The right most button on the bottom is the close button. Now re-open Stellarium.
6
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H.
Press the “
7
” button on your keyboard. This stops time. I.
Next go to DATE & TIME (clock icon on the vertical tool bar). Enter the date as
February 1
of the current year and the time as 21:00:00
(which is 9 p.m.). If you
notice the time at the bottom of the screen, you will see the time stopped.
J.
To make time move forward, you can press the “
L
” button (doing this more than
once will make time go faster and faster), to make it go backwards you can press
the “
J
” button, to return to normal you can press the “
K
” button. Press “
7
” again
to stop the time, and ensure it is still 21:00:00 hours on Feb 1.
K.
Click on SKY & VIEWING OPTIONS (3rd icon from the top on the left side, the
icon under the clock. This allows you to set the details in the sky. L.
Click on the SKY icon at the top of this window. Under the STARS box change
absolute scale to 2.5
, check mark labels and markers
and keep the slider
bar a bit to the left of the middle
. Make sure Atmosphere visualization
is not
checked.
7
M. In the SOLAR SYSTEM box, check mark Solar System Objects
and Show
planet markers
. Also check mark labels and markers
and keep the slider bar
a bit to the left of the middle
. N. Click the MARKINGS icon at the top of the window and in the CELESTIAL
SPHERE BOX check Cardinal points
. O.
Click the LANDSCAPE icon at the top of the window and click on OCEAN on the
left side. In the OPTIONS box check show ground
and uncheck all other boxes. 8
P.
Click on STARLORE tab and in the “Options” window check show labels. Then
click the X in the top right corner.
Q.
You are now ready to look at the screen! It shows the view from Dallas facing
south (there should be an S on the horizon line). Click on S and pull the horizon
to the bottom of the screen. Since we have set the landscape to “ocean” you will
only see the sky and a band representing the horizon at the bottom of the screen.
You can also move the sky. On PC computers you can use the “Page up” and
“Page down” buttons (not the arrow keys) to zoom in and out. On Apple
computers you can use the function key with the up arrow and down arrow keys
to zoom in and out.
9
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R.
Click the first two leftmost icons to show “Constellation Lines” and “Constellation
Labels.” Do you see some familiar patterns? Also, if you click on Constellation Art
(3rd icon from the bottom left) you can see the pictures superimposed on the
constellation. It would be preferable to keep Constellation Art turned off when you
look for answers to the specific questions, but you can turn it on every time you
are looking at something new, since it does help you visualize the pattern.
S.
Move the mouse so that you are facing the North. Date is February 01 and time
is 9 PM (21:0:0 Hr) You should see a red N at the horizon. Do you see an upright
question mark towards the right? This is the Big Dipper. If you click on each star,
you can read its name and lots of other data about it. For now, let’s focus on the
names. Starting from the bottom, they are Alkaid, Mizar, Alioth, Megrez, Phad,
Merak and Dubhe. Of these, Alkaid, Mizar, and Alioth are said to form “the
handle” and the other four stars form “the bowl” of the dipper. Take a few
moments to see if you understand what this means. Can you imagine a
saucepan-like dipper from this pattern?
T.
Click on Dubhe and notice that it also has α UMa written under its name. This is
its Bayer name. In addition to other information about Dubhe you can see that its
distance is 123.64 light-years. This means it takes light almost 124 years to get
to us from Dubhe.
1.
Which star in the Big Dipper has the Bayer name βUMa?
a.
Merak
b.
Phad
c.
Megrez
d.
Alioth
2.
What is the distance of the star Phad?
a.
125 ly
10
b.
79.5 ly
c.
83.18 ly
d.
300 ly
U.
Check the distances of all 7 of the stars in the Big Dipper. Which star is furthest away?
3.
The star in the Big Dipper that is furthest away is
a.
Phad
b.
Alkaid
c.
Mizar
d.
Dubhe
V.
Go back to Dubhe and note its Magnitude which is 2.00. Magnitude is a number that tells you how bright the star appears to be. A star barely visible to the naked eye in a very dark location is called magnitude 6, one that is a bit brighter is magnitude 5, one that is still brighter is magnitude 4 etc. Note that the smaller the number the brighter the star
!
W. Go to the other stars on the screen and notice their magnitude and names. Find
the star named Polaris and notice how Dubhe and Merak “point” to Polaris. For
this reason, most astronomers know Dubhe and Merak as the “pointer stars.”
4.
The magnitude of Polaris is
a.
3.2
b.
1.95
c.
2.5
d.
-1.6
5.
Which star appears brighter, Alioth or Polaris?
a.
Polaris appears brighter, since it is the brightest star in the sky
b.
Polaris appears brighter, since it is also called the North Star
c.
Alioth appears brighter, since it is closer to us
d.
Alioth appears brighter, since its magnitude is a smaller number than Polaris’.
X.
To see how the constellation names relate to the shapes, click the Constellation
Art button (third from left) in the tool bar at the bottom. You can see why the Little
Dipper containing Polaris is also called the “Little Bear”. Although it does have a
long tail which is unusual for a bear! You will have to use your imagination to see
the shapes.
Y.
The Big Dipper is actually an “asterism”, not a constellation. An asterism is an
easily recognizable pattern that is part of one or more constellations. Because
11
some of the constellation patterns are challenging to see, we chose an asterism
that is easy to spot. The Big Dipper is really part of a constellation called Ursa
Major – the Big Bear. If you shift your horizon a bit towards the east, you can see
the whole big bear. Play with the Constellation Art button to help you see the Big
Bear but turn it off before going further.
Z.
Another very useful constellation when you face north is Cassiopeia. It lies to the
upper left of Polaris, and you may have to change the position of the horizon to
see it. Notice how it looks like a W or M, with the middle star pointing towards
Polaris. It is supposed to represent a queen sitting in a chair!
AA.
Next, let’s advance the time and make it 11 PM on Feb 1. Go to the clock on the left tool bar which is date and time. Change the time to 11 PM (which is 23:00:00). What change do you see?
6.
At 11 PM on Feb 1
a.
The Big Dipper has moved closer to the horizon
b.
Cassiopeia and the Big Dipper have exchanged positions
c.
Polaris has moved higher in the sky
d.
Cassiopeia has moved closer to the horizon
BB.
Click on Polaris and note the Az/Alt numbers for Polaris. Az stands for
azimuth (how far the object is from north) and Alt stands for altitude, the height of
the star above the horizon.
CC.
Advance the time by 2 hours to 1 AM, 3 AM, 5 AM etc and notice how
Ursa Major and Cassiopeia move. Go through the whole day and see how the
positions change. Also note the Az/Alt numbers for Polaris throughout the day.
7.
In a few sentences (no less than two sentences) describe what you notice
about the position of Big Dipper and Cassiopeia.
8.
Polaris is an important star because
a.
It is the brightest star in the sky
b.
Its altitude remains constant throughout the night
c.
It shows the direction due north
d.
Both b and c are correct
DD.
Let’s face south. Scroll the horizon to get the red S on the horizon into
your field of view. Keep the date as Feb 1 of the current year, and input time as
10:00 PM. Notice the constellation called Canis Major and click on its brightest
star Sirius. Notice its distance and magnitude. You will use these numbers in
some upcoming questions.
12
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EE.
Click on another bright star to the right of Sirius called Rigel (in another
constellation). If you click on Rigel and scroll downwards, you will bring the
beloved constellation of Orion into view. Adjust the sky to keep Canis Major,
Orion, and Taurus in view.
FF.Orion is supposed to represent a hunter, with three stars forming his belt, Canis
Major is his dog and Taurus is a bull the hunter is chasing. It is fun to see the
Constellation Art figures superimposed on the constellation lines for these three
constellations.
9.
What do you think of the imagination of the ancient sky watchers? (use two
or more sentences)
10.Betelgeuse is the name of the star representing one of Orion’s shoulders. The name of the star representing his other shoulder is ___________.
11.Of the three stars in Orion’s belt, which star is furthest away?
a.
Alnitak
b.
Alnilam
c.
Mintaka
d.
They are all at the same distance
12.Sirius is an important star because
a.
It is the brightest star that we can see with a magnitude of -1.45
b.
It always points due south
c.
Its distance is 8.6 ly, which makes it further than Betelgeuse and Rigel
d.
Is part of Orion
GG.
Let’s use the “find” function in Stellarium. Click on the magnifying glass
(4th icon from the top on the left tool bar) and type in Regulus and click on the
magnifying glass icon. The screen will pan to show you the star Regulus. This
lies in the constellation of Leo the lion.
HH.
Click on Regulus and run time backwards by pressing J a couple of times.
You will see Leo go towards the eastern horizon. (Make sure you see the red E
on the screen). Press 7 to stop the backward motion until Regulus is just
skimming the eastern horizon, which means it is just rising. Look at the time on
the screen.
13.The rising time of Regulus on Feb 1 is about
a.
7 a.m.
13
b.
7 p.m.
c.
10 p.m.
d.
5 p.m.
II.
Change the date and time to August 1 at 10:00 PM (22:00:00). Use the magnifying glass to find the constellation Scorpius and its brightest star Antares. Scorpius is one of the few constellations that actually looks like what it is supposed to represent, a scorpion. Run the time forwards with the L key and backwards with the J key to determine the rise and set time on August 1.
14.
True or false: Scorpius will be visible at 3 AM on August 1
.
JJ. Now let’s examine the constellations of the zodiac. Familiar constellations like
Orion and Canis Major are not part of the zodiac, while Scorpius and Sagittarius
are. The zodiac also includes many inconspicuous constellations like Aries and
Capricornus, whose patterns are not very familiar. As explained in the
introduction, the constellations of the zodiac host the sun at various times of the
year. Hence to find where the Sun lies, we must change the time to daylight
hours. Naturally, the constellation will not be visible to us, but remember it’s still
there in the sky, the stars light is overpowered by the Sun. But thanks to our
computer simulation, we will be able to discern the pattern.
KK.
Choose date and time to be Jan 1 of the current year at 11:00 AM. Click
on the SKY AND VIEWING OPTIONS window (3rd icon from the top on the left
side). Next click the LANDSCAPE Icon at the top of the window. In the OPTIONS
BOX make sure the show ground is not checked. These settings will allow you to
see the Sun within various constellations over the course of one year. You can
click on the X at the top right side of the window before proceeding.
LL.Since there should be no atmosphere, the sky will appear black. If you had put a
check next to “show atmosphere”, you will see daylight and blue sky at 11 AM.
However, this makes it difficult for us to read constellation names.
MM.
Notice that “constellation boundaries” are drawn as red lines on the
screen. Remember the IAU drew these lines as a convenience, to divide the
celestial sphere into 88 regions. Each region hosts a constellation, and much like
geographical boundaries, the constellation boundaries are irregular.
NN.
Find the Sun (use magnifying glass icon). You can see that it lies in the
constellation of Sagittarius on Jan 1 at 11 AM.
OO.
Change the date to Feb 1 and record in the table below where the Sun
lies. Do the same for the first of every month.
15.Constellations that host the Sun this year.
Date
Location of Sun
(a) Jan 1
Sagittarius
(b) Feb 1
(c) March 1
14
Date
Location of Sun
(d) April 1
(e) May 1
(f) June 1
(g) July 1
(h) August 1
(i) September 1
(j) October 1
(k) November 1
(l) December 1
16.Have you ever read your daily horoscope? I’m sure you have! You probably
know whether you are a “Libra” or a “Pisces” and are aware that your birth
date determines your “sun sign.” Use any resource to find the name of the
“sun signs” on the first of each month.
Date
Sun signs
(a) Jan 1
(b) Feb 1
(c) March 1
(d) April 1
(e) May 1
(f) June 1
(g) July 1
(h) August 1
(i) September 1
(j) October 1
(k) November 1
(l) December 1
17.Compare the data you have tabulated in # 15 and #16. What do you notice? Are the two tables the same? In view of that, is the Sun really in the constellation of your “sun sign” on your birthday?
PP.To resolve this discrepancy, let’s change the year to 1,000 B.C, and find the
location of the Sun. To do this efficiently, click on the CLOCK icon, and change
the year to -1,000 (make sure you put the minus sign in front of the 1,000). Then
click on the X at the top of the Date and Time window. Use the table below to
record where the Sun lies on the first of each month in 1,000 B.C.
18.Constellations that host the Sun in 1,000 B.C.
15
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Date
Location of Sun
(a) Jan 1
(b) Feb 1
(c) March 1
(d) April 1
(e) May 1
(f) June 1
(g) July 1
(h) August 1
(i) September 1
(j) October 1
(k) November 1
(l) December 1
(The modern-day constellation boundary lines were drawn around 1930. But 3,000
years ago, constellations varied. So that the southern part of the constellation of the
modern-day constellation of Ophiuchus may have been considered part of the ancient
constellation Scorpius 3,000 years ago.)
19.What do you notice now? How does the table in #18 compare to table in #16?
20.The astrological sun signs were developed over 2,000 years ago! In view of what you notice, which statement best describes your conclusion?
a.
Horoscopes reflect the positions of the heavenly objects
b.
The Sun signs indicate the position of the Sun in the zodiac constellations
c.
The Sun signs indicate the position of the Sun in the zodiac constellation more than 2,000 years ago
d.
The Sun signs affect your personality
21.
What is the scientific reason for the discrepancy noticed in tables 15 and 18? Explain fully
.
QQ.
Change the date to your birthday (use the correct year, month and day).
Scroll over the Sun and record its rise and set time. Also scroll to any star in your
zodiac constellation and record its rise and set times.
22.Give the rise and set times of the sun and your zodiac constellation on your birthday. You can use the current year or the year of your birth, it 16
won’t matter much. In view of these numbers, will your astronomical constellation be visible in the night sky on your birthday? Use a few sentences to explain your answer fully, using the rise and set times you have determined.
23.What was your favorite constellation of all the ones you viewed? Give some reasons for your answer.
Congratulations! You are now an expert on constellations!
Rubric:
Questions 1-6 each worth 0.5 points each
Questions 7-14, 17, 19-21 each worth 1 point each
Questions 15, 16, 18, 22, 23 each worth 2 points
17