Caption: Jupiter's Galilean moons in collage.
The moons are in their right relative positions (inner to outer Io, Europa, Ganymede, Callisto), but not to scale. The images were taken by Voyager 1 in 1979 March.
Credit/Permission: NASA, 1979 / Public domain.
Download site: NASA: GRIN: Great Images in NASA.
Supplementary Lab Preparation: The items are often alternatives to the required preparation.
Caption: Portraet des Erasmus von Rotterdam am Schreibpult.
Desiderius Erasmus (1466/69--1536) hitting the books.
Credit/Permission: Hans Holbein the Younger (c. 1497--1543), 1523 (uploaded to Wikipedia by Erik Moeller (User:Eloquence), 2005) / Public domain.
Image linked to Wikipedia.
The quiz might be omitted if it's not feasible or convenient. The students may or may not be informed ahead of time of quiz omission depending on the circumstances.
The quizzes in total are 40 % of the course grade. However, only the top five quiz marks are counted.
In preparing for a quiz, go over the Required Lab Preparation.
The Supplementary Lab Preparation (see above) could help, but is only suggested if you feel you need more than the required Required Lab Preparation.
There is no end to the studying you can do, but it is only a short quiz.
One to two hours prep should suffice.
There will be 10 or so questions and the time will be 10 or so minutes.
The questions will range from quite easy to challenging.
The solutions might be posted at Jupiter Moons: Quiz Solutions. after the quiz is given. Whether they are or not depends on the circumstances of each individual semester.
The observations of the Galilean moons are only a small part of this lab.
So if weather is not good, just omit the observations.
The students will probably have another chance to observe Jupiter and the Galilean moons on another night just for fun.
Your's truly---after trying everything else first---has used the Customise page to make Fourmilab: Your Sky give a Las Vegas sky map at the current time.
Fourmilab: Your Sky is a bit tricky at first---not reading the instructions is a real hold-up---but you can use it to get a sky map above the horizon for any time and place.
I didn't set all possible options on. That would make the sky map too cluttered. But I did click on ecliptic-celestial equator, planets-Moon and constellation names.
Caption: Sky map: Las Vegas, Nevada, current time when refreshed.
Location and time data for Las Vegas, Nevada:
The abbreviations above are explained by the following linked terms: Pacific Daylight Time (PDT), Pacific Standard Time (PST), Coordinated Universal Time (UCT).
The planets are labeled by the planet symbols:
Alas and alack, the standard Uranus symbol has an HTML code, but it is not universally supported yet. So I give ☉ with spear on top (⛢, ♅), where the first bracketed item is what the unsupported code gives and the second bracketed item is the astrological Uranus symbol---which isn't much good for anything---but it is supported.
Credit/Permission: John Walker: Fourmilab: Your Sky, 2003 / Public domain.
Image linked to Fourmilab: Your Sky.
Alignment is NOT needed since Jupiter is easy to find by hand.
See Telescope Operating Procedure for procedures and tips.
Since the observations are such a small part, probably only 8 C8 telescopes need to be set up even if all three sections are doing Jupiter Moons.
The sections can cycle through using them.
You can set out the appropriate smaller focal length eyepieces on the cart for students to get and return.
Make sure the students are instructed to loosen, but not remove, the screws when changing eyepieces.
If they remove the screws, the screws may fall on the ground and be lost forever in the crevasses.
The 40 mm eyepieces should be back on the C8's at the end of the night.
Don't let the students walk off with eyepieces in their pockets.
See CCD Camera Instructions if the CCD camera is to be set up.
They'll be on a shelf somewhere.
There probably are NOT enough for all groups in all sections to have their own protractor and ruler.
Maybe grab 5 or each section---don't take too many or the other lab instructors will become hostile.
You should put out the List of Tricks for C8 Telescopes.
You also need to assign each group a particular Galilean moon for the lab to be their Galilean moon for the Clea Galilean moons software part.
You could do this later or put on sheets of paper on the tables for the groups to collect as they form.
The astro labs are active learning environments. Students quite rightly get impatient with lengthy intros.
Point out to them the List of Tricks for C8 Telescopes---and tell the students to leave the Tricks sheets for collection at the end of the night---they can be re-used.
Remind them especially of telescope shutdown for the night if they are the last users of the C8's for the night---if they don't do it, someone else will---you?
Then give a brief description/reminder of what they will be doing with the C8's which is just to sketch Jupiter and the Galilean moons.
They will have to find and center Jupiter for themselves since the C8's will probably not be aligned.
Tell them about changing eyepieces.
The ones not handed back can be left on the front desk for students to collect at their leisure.
Caption: "Red foxes (Vulpes vulpes) at the British Wildlife Centre, Horne, Surrey, England." (Slightly edited.)
Credit/Permission: © Keven Law, 2008 / Creative Commons CC BY-SA 2.0.
Image linked to Wikipedia.
We can check whether Jupiter is in the night sky on the sky map below
The planets that are currently in the sky are illustrated in the sky map below.
The planets are labeled by the planet symbols:
Caption: Sky map: Las Vegas, Nevada, current time when refreshed.
Location and time data for Las Vegas, Nevada:
The abbreviations above are explained by the following linked terms: Pacific Daylight Time (PDT), Pacific Standard Time (PST), Coordinated Universal Time (UCT).
The planets are labeled by the planet symbols:
Alas and alack, the standard Uranus symbol has an HTML code, but it is not universally supported yet. So I give ☉ with spear on top (⛢, ♅), where the first bracketed item is what the unsupported code gives and the second bracketed item is the astrological Uranus symbol---which isn't much good for anything---but it is supported.
Credit/Permission: John Walker: Fourmilab: Your Sky, 2003 / Public domain.
Image linked to Fourmilab: Your Sky.
Here a modern diagram of the inner Solar System plus Jupiter.
The diagram is to scale.
Emphasize to the students the utility of the astronomical unit (AU) as the natural unit for Solar System distances.
Copernicus himself first discovered the true relative Solar System distances in terms of the astronomical units.
This was made possible by his adoption of a heliocentric solar system model.
No one before Copernicus knew what those relative distances were.
Caption: The inner Solar System plus Jupiter which is in the outer Solar System.
The Asteroid Belt and Jupiter Trojan asteroids are shown. The diagram is to scale.
This is a view from the North Pole side of the Earth's orbital plane which, in astro-jargon, is the ecliptic plane. This is the customary way to view the Solar System face-on.
The planets and almost all asteroids orbit counterclockwise from this perspective. A very few asteroids orbit clockwise which is called retrograde motion.
The "Greeks" are the leading Trojans and the "Trojans" are the trailing Trojans---except that 617 Patroclus got into the "Trojan camp" and 624 Hektor got into the "Greek camp".
The astronomical unit (AU) is the mean Earth-Sun distance.
It is the natural unit for Solar System distances---no one grasps such distances in kilometers or miles---but the media keep quoting them mindlessly anyway.
In astronomical units the mean planet-Sun distances are as follows:
In astronomical units, the Solar System size scale is comprehensible.
Credit/Permission: User:Mdf, 2006 (uploaded to Wikipedia by User:Dronemvp, 2007) / Public domain at least in USA.
Image linked to Wikipedia.
Caption: The first two of Kepler's 3 laws of planetary motion illustrated compactly.
The 3 laws are:
This means the planets move faster the nearer they are to the Sun.
The 3 laws also are exact for ideal systems (which we will not describe here).
Credit/Permission: © Han-Kwang Nienhuys (AKA User:Hankwang), 2007 / Creative Commons CC BY-SA 3.0.
Image linked to Wikipedia.
Caption: The major moons of the Solar System shown to scale with the Earth for comparison.
They have been selected for large size or some special interest.
The displayed moons (in order of increasing mean orbital radius) for each parent planet or other astro-body are given below with mean diameter in some cases and size order for the largest ones (in brackets):
See also Wikipedia: Natural Satellites and Wikipedia: List of the natural satellites.
Credit/Permission: NASA, 2005 (uploaded to Wikipedia by User:SG, 2007) / Public domain.
Image linked to Wikipedia.
Caption: An animation illustrating the 1:2:4 Laplace resonance of the orbits of Jupiter's Galilean moons Io, Europa, and Ganymede.
The 1:2:4 Laplace resonance forces the orbital periods of these Galilean moons to be in the ratio 1:2:4 running Io (orbital period 1.769 days), Europa (orbital period 3.551 days), and Ganymede (orbital period 7.155 days).
The actual orbital periods are NOT exactly in the 1:2:4 ratio as one can see from the values above.
Gravitational perturbations from other astro-bodies probably constantly disturb the actual ratio away from the exact 1:2:4 ratio, but the 1:2:4 Laplace resonance is stable meaning that restoring forces constantly drive the system back toward the exact 1:2:4 ratio.
The outermost Galilean moon Callisto (orbital period 16.69 days) has avoided being in a Laplace resonance with the Galilean moons.
Probably in Callisto's case gravitational perturbations overcome the any Laplace resonance effect.
The animation gives the exact 1:2:4 Laplace resonance for illustrative reasons.
You can see the 1:2:4 ratio if you concentrate on two of the Galilean moons at once.
All the Galilean moons are tidally locked to Jupiter.
Thus, their axial rotation periods are the same length as thier orbital periods and they always turn nearly the same face to Jupiter.
Credit/Permission: User:Matma Rex, 2011 / Public domain.
Image linked to Wikipedia.
Caption: Standard protractor.
A protractor is a divided circle used for measuring angles.
To make a measurement, the protractor center of rays is centered on the vertex of the angle you wish to measure.
Then the angle you wish to measure is defined by two rays that radiate from the vertex.
The two rays go through whatever two points you are trying to measure the angle between from the vertex you have chosen.
Credit/Permission: © User:Scientif38, 2011 / Creative Commons CC BY-SA 1.0.
Image linked to Wikipedia.
The instructor should draw a version of the Jupiter diagram on the board and describe what is on it and what the students have to do with it.
On the Jupiter diagram, Jupiter is the vertex for all the angles we will draw.
In fact, yours truly suggests only that one angle is needed no matter what the lab manual says.
The instructor will give you the angle between the direction to the Earth (indicated on the diagram) and the direction to the Sun with vertex at Jupiter.
Use a protractor to draw a line in the direction to the Sun that passes through Jupiter and crosses all moon orbits on both sides.
Draw two parallel lines to this line that sandwich Jupiter.
The region between the parallell lines away from the Sun is the umbra (i.e., shadow) of Jupiter or the eclipse region.
Three corrections---if they havn't been corrected by now:
Some absolutes for the Excel spreadsheet
We are using Universal Time (UT) and 24-hour clock throughout this lab.
For reasons known only to Microsoft, once you write down an AM or PM, Excel spreadsheet will never forget that and will wreck all the formulas in a way that cannot be undone.
Do NOT just click print---that could result in the spreadsheet page to be printed over 20 pages or so.
Click print preview, setup, and fit to 1 page. Then print the spreadsheet page on 1 page.
You will just sketch Jupiter and the Galilean moons.
The C8 alignment that allows object searches and turns on the clock drive will be/will NOT be set.
You will have to center Jupiter with the star pointer and the finderscope to put it in the field of view of the C8
The Galilean moons will be approximately along the east-west line.
But to get the
______________________________________________________
C8 telescope specifications for available eyepieces
______________________________________________________
focal length magnification approximate
fields of view
(arcminutes)
______________________________________________________
40-mm 50 X 40
25-mm 80 X 30
18-mm 111 X 20
12.5-mm 160 X 14
9-mm 222 X 10
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The exact values actually vary in time.
The values as of 2013 from Wikipedia are given in the table below.
______________________________________________________
Table: Orbital Periods of the Galilean Moons
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Moon Orbital Period
(days)
______________________________________________________
Io 1.769 137 786
Europa 3.551 181
Ganymede 7.154 552 96
Callisto 16.689 018 4
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Caption: Film poster for the TheMummy (1932) starring Boris Karloff (1887--1969).
Credit/Permission: Employee or employees of Universal Pictures attributed to Karoly Grosz (fl. 1930s), 1932 (uploaded to Wikipedia by User:Crisco 1492, 2012) / Public domain.
Image linked to Wikipedia.