What is the Saros cycle?

The Saros cycle is an eclipse pattern of roughly 18 years, 11 days, and 8 hours. After one Saros period, the Sun, Moon, and Earth return to nearly the same relative geometry, producing a similar eclipse. The cycle was first discovered by Babylonian astronomers around 575 BCE through systematic observation recorded on clay tablets.

What is Lunar Saros 138?

Lunar Saros 138 is a family of 82 lunar eclipses spanning 1,460 years, from October 15, 1521 to March 30, 2982. It began with faint penumbral eclipses, crossed into partial eclipses in 1918, and will produce its first total lunar eclipse in 2044. The August 28, 2026 eclipse is its deepest and final partial eclipse.

Why is it called the Saros cycle?

The name is a historical misattribution. In 1691, Edmond Halley borrowed the word “Saros” from a Byzantine lexicon, believing it was the ancient Babylonian term for the eclipse cycle. In fact, the Babylonian word šār meant 3,600 — a unit of measurement, not an eclipse period. The French astronomer Guillaume Le Gentil pointed out the error in 1756, but the name had already become standard.

What is the exeligmos?

The exeligmos is a period of three Saros cycles — roughly 54 years and 33 days. Because each Saros period shifts the eclipse’s visibility zone by about 120 degrees of longitude, three full cycles return the eclipse to approximately the same part of the world. The term comes from ancient Greek astronomy.

When is the next total lunar eclipse from Saros 138?

The first total lunar eclipse of Lunar Saros 138 will occur on September 7, 2044. It begins a run of 26 total eclipses that will continue until 2495, with the longest — 105 minutes and 24 seconds — occurring around the year 2369.

The Family of Shadows: How Lunar Saros 138 Traveled Five Centuries to Find You

Lunar Saros 138 began on October 15, 1521, and arrives at its final partial eclipse on August 28, 2026. Journey through the Babylonian discovery of the Saros cycle, Edmond Halley’s beautiful mistake, and the 1,460-year story of a single family of shadows.

Category: Eclipse Season
Published: August 28, 2026
Author: Ashe
Read time: 10 min

Frequently asked questions

What is the Saros cycle?: The Saros cycle is an eclipse pattern of roughly 18 years, 11 days, and 8 hours. After one Saros period, the Sun, Moon, and Earth return to nearly the same relative geometry, producing a similar eclipse. The cycle was first discovered by Babylonian astronomers around 575 BCE through systematic observation recorded on clay tablets.
What is Lunar Saros 138?: Lunar Saros 138 is a family of 82 lunar eclipses spanning 1,460 years, from October 15, 1521 to March 30, 2982. It began with faint penumbral eclipses, crossed into partial eclipses in 1918, and will produce its first total lunar eclipse in 2044. The August 28, 2026 eclipse is its deepest and final partial eclipse.
Why is it called the Saros cycle?: The name is a historical misattribution. In 1691, Edmond Halley borrowed the word “Saros” from a Byzantine lexicon, believing it was the ancient Babylonian term for the eclipse cycle. In fact, the Babylonian word šār meant 3,600 — a unit of measurement, not an eclipse period. The French astronomer Guillaume Le Gentil pointed out the error in 1756, but the name had already become standard.
What is the exeligmos?: The exeligmos is a period of three Saros cycles — roughly 54 years and 33 days. Because each Saros period shifts the eclipse’s visibility zone by about 120 degrees of longitude, three full cycles return the eclipse to approximately the same part of the world. The term comes from ancient Greek astronomy.
When is the next total lunar eclipse from Saros 138?: The first total lunar eclipse of Lunar Saros 138 will occur on September 7, 2044. It begins a run of 26 total eclipses that will continue until 2495, with the longest — 105 minutes and 24 seconds — occurring around the year 2369.