“Bennu’s rotation rate is speeding up over time by about 1 second each century.”
Measurement error.
Is it spinning right or left? In particle physics this creates different attributes.
If there is outgassing from inside the rock it would cause the rotation to quicken. Because an ordinary spinning object in space should continue spinning at the same rate, unless an outside force acts upon it.
“Measurement error.”
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My thinking, too. At 1 second each century it would have to be observed a looooong time to say if it’s speeding up, slowing down or no change at all.