QUOTE OF THE DAY
With ordinary talents and extraordinary perseverance, all things are attainable.
— Sir Thomas Buxton
I am excited about the New Horizon's flyby of the Pluto system (Figure 1) occurring on July 14, and I will be glued to my computer as the data is returning. Fortunately, there is already some data coming back on Pluto and its moons. One interesting aspect of the Pluto system is the fact that the mass ratio of Charon to Pluto is large enough that the barycenter of their orbit is outside the bodies of both Charon and Pluto.
My goal here is to compute the location of the barycenter and compare my results with the published data.
For a terrestrial example of the barycenter concept, I have included a video showing a hammer thrower (Figure 3). Notice how the human and the ball rotate about a point in-between them, just like Pluto and Charon.
I used to throw the discus in high school – I remember well the feeling of rotating about a point outside of my body.
Figure 4 shows my calculations for the barycenter of the Pluto and Charon.
My results for the barycenter distances agree with those in the Wikipedia's article on Charon.
Just a quick calculation to verify that I am seeing Pluto and Charon rotating about a point that is clearly between the two of them.
To whet your appetite for the New Horizon's mission, Figure 5 (source) provides a quick look at how New Horizon's will encounter the Pluto system.