More or less, though picking nits, there are a number of different definitons of "year", depending on how one measures the earth going around the sun. One usual definition is the time between vernal equinoxes, however there are a number of subtle isues here.
To a level of 4 significant figures, though, the statement will be correct by most any of the possible subtly different definitions of "year".
As far as timekeeping goes, though, our atomic clocks keep much more accuarate time than astronomical motions do, and have become our primary time standard.
Atronomical motions will also not be very useful for a hypothetical space traveler as far as measuring time - he will not base his units of time by the astronomical motions of a distant planet around a distant sun (he won't even be able to observe them in real time). He will base his time on the atomic clocks that he caries with him.