M27
MPC OSERVATORY 643
Astronomical Research
Dedicated to expanding human knowledge
Saturn
DISCOVERY OF MINOR PLANET CO-ORBITALS
We discovered (32207) and (32208) both on the evening of July 27, 2000.  They were conditionally designated 2000 OQ7 and 2000 OR7, respectively.  At that time they were only 1 arcminute apart in RA, although their vertical separation was 1/2 degree.  They were both 18th magnitude and had very similar orbital elements.

When their orbits were better known, we found that (32208) orbits only about 5 million km farther out than (32207), taking about 33 days longer for each orbital period.  Both objects have very circular orbits with only slight inclinations.

We were able to determine that just prior to discovery, on July 4, 2000, they passed only about 2 arcmin from each other in our sky - that is just 3 times the apparent size of Jupiter from Earth!  This event coincides with the maximum northern elongation of (32208) above the ecliptic plane, suggesting an orbital relationship between the objects.  Then on August 13, 2000 they passed within less than 8 million km of each other in space, a near-miss by planetary standards.

The next time that (32207) passes (32208) in its orbit will be September of 2223 CE.  However, they will be tens of millions of km apart.  They will continue to overtake each other approximately every 220 years, but only every other event will be a close one.

This means that we discovered them the first time they were close to each other in our sky in about 440 years!  We believe this orbital "dance" is the evidence of a relatively recent collision event which split these objects from the same parent body.