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For comparison, once Voyager 1 has shaken the Sun’s gravitational pull, it will be traveling at about 13 km/s through interstellar space.
We know that Rama is rocky because it’s not producing a tail.
A swimming race illustrates the simple principles involved in measuring time.
This swimmer is competing in a 1,500 metre race and we have an accurate, calibrated wristwatch.
Everything we know comes from observations like this, so while we can determine speed and position, we have to estimate size and mass.
We can tell that Rama is new to the neighborhood because it is traveling far too fast to be gravitationally bound to the Sun.
But without reliable witnesses the accuracy of the watch makes no difference.
You can only establish the time for the race if it was timed by two or more qualified eyewitnesses who observed the start, the progress and the finish.
Without these observations you cannot be sure that the time is valid.
If it hadn’t been so nearby, we probably never would have noticed it.
So if interstellar visitors are rare, then we are seriously lucky.
That is why you need at least two, sometimes three judges to measure the time of the race to the standard needed to enter the record books.
It would make no difference how accurate or high-tech the wristwatch was.