Nothing is Certain

From the Wall Street Journal's Science column:

Not everything in the solar system adds up, of course. The moon's actual orbit is off its calculated course by about six millimeters a year. No one knows why. The standard yardstick for length on an interplanetary scale, the Astronomical Unit, grows by about seven centimeters a year. Scientists have yet to agree on an explanation.

I'm not sure which surprises and pleases me the most -

1. Scientists can measure the moon's actual orbit to a precision of six millimeters
   
2. Scientists can measure that and still not know why
   
3. Scientists are willing to admit freely that they have observed something they can't explain

I really like the honesty of having an observation and saying "we don't have a clue why this is" - it's refreshing. Why can't politicians do that?