It is the "third part" of stars that fall. This is a time reference to "powers-that-be" in the third age.
The first was the first millenium from Egypt, the second was the two afterward (time, times and a part).
The third is the third age, which follows from then (1607 to 1997, per Ezekiel).
The powers that came to be in this period are what are hitting the ground now.