noun
saros period; saros cycle
Astronomical term for the approximately 18-year 11-day cycle after which eclipses repeat.
サロス周期は約18年と11日で、日食や月食が繰り返される。
The saros period is about 18 years and 11 days, after which solar and lunar eclipses repeat.
From English 'saros' (ultimately from Babylonian) + 周期 (cycle).