Stars and frost
Another question from the Scrap Sack:
The passing of the years is referred to as "letting the stars and frost go by" (星霜を送る). As frost comes down once a year you could call it a sign [of a year's passage]. But the stars come out in the sky no matter what season it is. It is difficult to tell [from the stars] when one year ends and another begins. What say you?
And the (meat of the) answer:
The stars do come out in the sky all through the year, but they also move around the sky. This expression refers to the counting of these cycles [and therefore the years].
Can't argue with that. I looked up 星霜 in the Nihon kokugo daijiten and found that it is pronounced seisō (originally seizō) and does indeed mean "years." That's "years" in the general sense of "reeling in the", not the specific sense of "four more", although apparently it has been used in the latter sense in the modern era; the example they give is 二星霜 for "two years" in a 1907 sentence by Tsunashima Ryōsen 綱島梁川).
The earliest attestation they have for the word is in a poem by Liǔ Zōngyuán 柳宗元, so it was no doubt borrowed whole from Chinese.
Anyway, after explaining that the stars move, the answer goes off on a bit of a tangent (partly involving the year star) that I won't translate here. But I did learn that while most of the stars move one way, the ascending lunar node, a.k.a. "Rahu star" (羅睺星), moves the other. (Basically — see comments.) (Ketu's node gets a pass, probably because Ketu isn't evil.)
Charles:
What?!? It isn't difficult to tell the duration of a year from the stars, in fact, that's exactly how you determine it. I am surprised to hear of such an assertion, considering the astrological basis of the Japanese timekeeping system.
BTW, the lunar nodes are not always retrograde. Occasionally they move anterograde.