The March 13-14, 2025 Lunar Eclipse: Science, History, and Atmospheric Insights

We encourage you to join the brotherhood and sisterhood of lunar eclipse gazers this month as the night sky is set to dazzle us with the first total lunar eclipse since 2022. On the night of March 13-14, 2025, the moon will slip into Earth's shadow for about an hour, taking on a deep reddish hue, some call it a "Blood Moon". North and South America will offer the best views, while observers in parts of Europe may catch a glimpse at moonset, and those in East Asia will see it as the moon rises. Here is a link courtesy of NASA with visualizations of this lunar eclipse visibility map: https://svs.gsfc.nasa.gov/5473

But why do lunar eclipses matter? Lunar eclipses have fascinated humanity for millennia, serving as both awe-inspiring spectacles and critical scientific events. They occur when the Earth appears centered between the sun and the moon, casting a shadow that causes the moon to appear reddish. Beyond their visual splendor, lunar eclipses hold significant scientific and cultural importance.

A lunar eclipse unfolds in stages, beginning with the penumbral phase, where the moon enters Earth's outer shadow (penumbra), leading to a subtle dimming. This is followed by the partial eclipse phase, as the moon moves into the Earth's umbra (inner shadow), creating a noticeable darkening. The climax of the event is the total eclipse, where the moon is fully enveloped by the Earth's umbra, resulting in its characteristic reddish hue. This occurs due to the scattering of sunlight through Earth's atmosphere—a process similar to the one that gives us red sunsets.

Lunar eclipses provide astronomers with a unique opportunity to study both Earth’s atmosphere and the Moon’s surface. By analyzing the color and brightness of the eclipsed Moon, scientists can gain valuable insights into the composition and density of Earth’s atmosphere. The absence of direct sunlight during an eclipse also allows for clearer observations of the Moon’s surface, aiding in geological studies.

We contacted Moon expert Robert Reeves about the scientific value of lunar eclipses: Reeves highlighted the importance of the Danjon Eclipse Scale, a system used to classify the brightness and color of the Moon during a total lunar eclipse. Ranging from L=0 (nearly invisible, dark Moon) to L=4 (bright copper-red), the scale reflects how much sunlight is refracted through Earth’s atmosphere. This refraction is influenced by factors such as volcanic eruptions, air pollution, and cloud cover.

By applying the Danjon Scale, scientists can track atmospheric changes over time. For instance, after the 1991 Mount Pinatubo eruption, the Moon appeared unusually dark due to high concentrations of volcanic ash in the stratosphere. Comparing eclipse brightness across decades helps researchers monitor trends in atmospheric clarity and pollution levels.

Lunar eclipse studies have evolved from Theodor von Oppolzer’s Canon der Finsternisse (1887) to Fred Espenak and Jean Meeus’ Five Millennium Canon of Lunar Eclipses (2009), which provides precise eclipse predictions. Combining these studies with the Danjon Scale allows scientists to use lunar eclipses as a natural atmospheric sensor, offering a unique method for observing Earth’s changing environment.

As we prepare to witness this celestial event, it's worth reflecting on the earliest recorded lunar eclipse known to us. Some researchers believe this distinction may belong to the Babylonians.

In the annals of history, ancient civilizations gazed at the night sky with a mix of wonder and reverence. Among these early astronomers, the Babylonians stood out for their meticulous record-keeping and sophisticated understanding of celestial phenomena. One of the most remarkable records from this era is the earliest known documentation of a lunar eclipse, found in the Babylonian "Enuma Anu Enlil" tablets, specifically in Tablet 20, dating back to around 1375 BCE.

For the Babylonians, the heavens were a source of divine messages, and celestial events like lunar eclipses were seen as powerful omens. The "Enuma Anu Enlil" tablets, a comprehensive collection of omens and astronomical observations, capture this intricate relationship between the gods and the cosmos. Tablet 20 stands out for its detailed recording of lunar eclipses, showcasing the Babylonians' advanced observational skills.

These records not only provided precise timings and characteristics of the eclipses but also served as powerful tools for astrological predictions and the development of more accurate calendars. By carefully observing and documenting these events, the Babylonians refined their understanding of the lunar cycle and influenced subsequent civilizations who built upon their astronomical achievements.

Exploring The Moon With Robert Reeves

The Espenak and Meeus Lunar eclipse Canon is available online at

Babylonian "Enuma Anu Enlil"

Total Eclipse of the Moon (26 May 2021)

by rdk_CA on Astrobin: https://app.astrobin.com/i/fdu20j