I took many images like the following:

enter image description here

As many of you may recognise, this is a picture of Jupiter and its four Galilean moons. Using these images, I am aiming to calculate the mass of Jupiter by finding the orbital distance and orbital period of each of these moons, and then plugging those values into Kepler's Third Law.

However, this requires a seemingly tedious process of the following sort:

1) Locate the centre of mass of Jupiter

2) Measure the distance to each of the planets

I have a lot of data (many, many pictures). I am hoping that there is a relatively easier (or even more accurate) method of doing all of the above than using software like Gimp to do everything for each image manually. Can anyone recommend anything?

  • $\begingroup$ If it's tedious, why do it? $\endgroup$
    – James K
    May 21, 2016 at 6:14
  • $\begingroup$ I want to see if I myself can get a value close to the accepted value, which would blow any amateur astronomer's mind. And so, was wondering if there was a short cut I could take in the labor work, which is not the interesting part of this scientific exploration. $\endgroup$ May 21, 2016 at 6:18
  • 4
    $\begingroup$ If I were doing this I would read the images into Matlab or Gnu-Octave and write code to find the centroid of the Jupiter and satellite images and proceed from there, but if you are not familiar with programming and/or image manipulation this may well not be up your street. $\endgroup$ May 21, 2016 at 7:20

1 Answer 1


Try WinJupos. It can be used to measure Jupiter (as well as other planets)


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