a) Choose any still image and record the location of the GRS among zones/belts and its latitude in degrees (°):
b) Do the same for the location of the LRS among zones/belts and its latitude in degrees (°):
Go back to the movie sequence and observe the rotation of the GRS and LRS.
a) Is the GRS rotating clockwise or counterclockwise?
b) Is the LRS rotating clockwise or counterclockwise?
What do you think keeps the GRS spinning over such a long period of time? Explain.
Choose one of the later images between numbers 70 and 80. Since the Cassini space probe was approaching Jupiter while this sequence of images was taken, the later images are of better quality than the initial images. By comparing the longitude of the eastern edge of a feature to the longitude of the western edge, the sizes of the object can be found.
a) Find the diameter of the GRS in degrees longitude:
b) Find the diameter of the LRS in degrees longitude:
Jupiter’s circumference is 4.5 x 105 km. This corresponds to a full 360° in longitude around the equator. Use this information to calculate the scale factor for converting degrees of longitude into kilometer (km). Find the number of km per degree.
Scale factor: _______________ km/°
Use this scale factor from above and your diameter measurement of the GRS/LRS in question 4 to convert their diameters to km:
a) Diameter of GRS: ______________ km. Show your work.
b) Diameter of LRS: ______________ km. Show your work.
If the Earth’s diameter is 12,756 km, how many times larger or smaller are these features compared to Earth?
a) GRS: _________________. Show your work.
b) LRS: _________________. Show your work.
Now change back to the motion sequence and observe the motion of the GRS and LRS as they migrate across the planet.
a) Is the GRS moving East or Eest?
b) Is the LRS moving East or West?
First, we will determine their change in position between the first (1) and last (82) still image.
a) click on the first image in the rightmost panel and record the longitude of the center of the GRS in image 1. This is the starting longitude.
b) Click on image 82 and record the longitude of the center of the GRS in image 82. This is the ending longitude.
c) So, how much did the GRS move in longitude, i.e. experience a change in longitude? Show your work.
Do the same to measure the motion of the LRS:
a) Starting longitude
b) Ending longitude
c) Change in longitude
In order to find the drift speed, we also need to know how much time has passed between the starting and ending measurements. The time unit based on one of Jupiter’s rotations is called 1 Jovian Day or 1 JD. Remember, the time between two successive images is equal to 2 of Jupiter’s rotations. Record the total time between image 1 and image 82 in units of JD:
Total number of Jovian Days: _______________ JD. Show your work.
Finally, the speed of any feature can be found by dividing distance by time. Use the change in longitudes and the number of Jovian Days from above to calculate the drift speeds of the GRS and LRS in degrees per Jovian Days ( °/JD).
a) GRS: ________________ °/JD. Show your work.
b) LRS: _________________ °/JD. Show your work.
At the latitude of the GRS, a difference in speed of 1 °/JD translates to about 30 ms. The speeds are faster closer to the equator and sloer as you move away from the equator. The LRS is not much further south thant the GRS. So, we will assume the same speed in m/s for the LRS.
a) What is the speed of the GRS in m/s? ________________ m/s. Show your work.
b) What is the speed of the LRS in m/s? ________________ m/s. Show your work.
Watch the movie (animated sequence of images) and identify the fastest moving eastward cloud band and the fastest moving westward band (can either be a zone or belt).
a) Switch to any still image and identify their names:
b) In which hemisphere(s) are they located?
c) Look again at the movie. Would you say that the fastest cloud bands traveling to the East are zones or belts?
We will track THREE objects to measure their actual speeds. Examples are shown in image 4. Note that you will be switching between the movie and the still images. Always use the still images to determine the names of the features and their measurements.
I. One of the dark elongated features, or hot spots, near the border of NEB and EZ.
II. One of the small dark round features at about the same latitude as the Great Red Spot.
III. One of the White Oval storms south of the GRS.
Follow all steps in the bulleted list up to the bullet that refers to Table 2.
Continue following the steps in the bulleted list starting with the step involving Table 2. Fill in Data Table 2 below as you go along.
Compare the wind speeds for the zones/belts that you just calculated.
a) Which of the zones/belts has the highest wind speed?
b) How do these wind speeds compare to the drift speeds of the GRS and LRS? Explain.
c) Wind speeds in the jet streams of Earth are usually around 120 mph. How do the speeds in Table 2 compare with winds on Earth?
Go back to the movie and watch the small dark round features (like the one you chose to track in Table 1). Describe what happens when they run into the GRS.