07/09/2025
SCIENCE EXPLAINER | Mesmerizing Midnight: Lunar Eclipses and their Significance
By: Keegan Abeja | 11 STEM Francium
The clock ticks as the moon begins its path toward totality. Observers watch in anticipation, first the slight shadow of the penumbra, then, minutes later, the umbra takes hold. At last, the sky unveils its spectacle â a blood-red moon glowing against the night sky.
Later tonight, starting at around 11:30 PM, the Philippines will experience its first total lunar eclipse since November 8, 2022.
In a year, only 2-3 lunar eclipses occur around the globe â total eclipses are even rarer, with only 1 in 4 lunar eclipses reaching totality. This rarity gives it cultural and scientific significance.
LUNAR LOCKDOWN
Lunar eclipses occur when the Earth goes between the Sun and the Moon, where the Sun then casts Earthâs shadow onto the Moonâs surface, which causes the Moon to appear red-ish in color, often being described as a âblood moonâ.
The red color is because when sunlight reaches the Earth, the atmosphere filters different wavelengths â shorter wavelengths like blue light are scattered outward, whilst longer wavelength red lights are refracted onto the lunar surface, causing the blood moon-like appearance.
PATH TO TOTALITY
Entering the Penumbra - During lunar eclipses, the Earthâs shadow has two parts, the central umbra, and the surrounding penumbra. In this stage, the eclipse hasnât actually started, but the Moon begins to approach the penumbra. At this point, you start to see a faint penumbra shadow on one of the Moonâs edges.
Penumbra - Here, the Moon has entered the penumbra, and a light shadow is seen covering a chunk of the Moon. The shadow engulfs the Moon more and more as minutes pass until it begins to enter the umbra.
Umbral Embrace - At this stage, the Moon begins to enter the Earthâs dark central shadow cone â the Umbra. A much darker shadow appears and progressively engulfs the lunar surface, and may even look as if the Moon is being swallowed by darkness, but later, an orange/red hue starts to appear.
Minutes to Totality - When around 75% of the Moon is covered by the Umbra, the darkness fades, and a part of the Moon glows brightly. During this stage, the Moon will reflect different colors, the deep black of the Umbra, and a red-ish tint, and light silver to a faint blue caused by atmospheric scattering and ozone absorption. This causes a beautiful phenomenon called the âJapanese lantern effectâ due to the stark contrast in colors.
Total Eclipse - The highlight â figuratively and literally â of the lunar eclipse, by this stage, the Earth has reached totality, or when the Earthâs shadow has completely engulfed the Moon. At this point, the Moon will usually glow red or orange and is often described as a blood moon. The outer edges of the Moon may also appear as a light silver or blueish white.
Leaving Totality - The Moonâs bright glow starts to emerge from the umbra and penumbraâs shadows. During this stage, you may also see the âJapanese lantern effectâ again.
Penumbral Re-entry - By this point, the Moon will have left the umbraâs dark shadow cone and will re-enter the penumbra. The darker umbral shadow is replaced by the lighter shadow of the penumbra, while the Moonâs light starts to shine bright again on the Moonâs outer edges.
Penumbra - The Moon has re-entered the penumbra and its light shadow is again cast upon the Moonâs surface.
Lunar Glow - The end of the eclipse, the Moon has completely exited the Earthâs shadow and once again shines brightly in the night sky.
TYPES OF LUNAR ECLIPSES
Total Lunar Eclipse - This is the type described earlier, where the Earthâs shadow is cast upon the entire surface of the Moon. Here, the entire Moon will usually glow red or orange.
Partial Lunar Eclipse - Here, the Moon only partially enters the Earthâs shadow. This gives it the appearance as if a shadow is swallowing a part of the Moon. How much of the Moon is swallowed by the shadow depends on how the Earth aligns with the Sun and the Moon.
Penumbral Lunar Eclipse - Compared to the two, only the penumbral shadow is cast upon the Moon. This can make it difficult to see and may not even be noticeable or significant to the naked eye.
Compared to solar eclipses, lunar eclipses can be observed by the naked eye since the eclipse is caused by the Earthâs shadow being cast onto the Moon, whilst the Moon is the one that goes in front of the Sun, and while it does appear the Moon is blocking out the Sun, you will still need eye protection to shield your eyes from the intense UV and infrared rays the Sun outputs.
MODERN IMPORTANCE
Cultural Consequence
In Philippine mythology, it is believed that a large sea serpent named âBakunawaâ has swallowed the Moon, causing it to disappear. Thus, they are often seen as bad omens, with rituals being made to ward them off.
For example, superstitions and practices of banging pots and pans are often done during a lunar eclipse, in the belief that it will ward off evil and Bakunawa.
Similarly, in other mythologies like Chinese, Norse, Mesopotamian, Egyptian, and Hindu, it is also believed that a large monster swallows the Moon, with people making loud noises to scare it off.
Scientific Significance
During a lunar eclipse, the hue the Moon gives off during totality can help planetary scientists study and understand more about the current composition and behavior of the Earthâs atmosphere.
A lunar eclipse has also played a crucial role in proving Albert Einsteinâs theory of general relativity, where in 1919, the bending of sunlight was observed and provided evidence in proving the theory.
Furthermore, animals have been shown to change their behavior during lunar eclipses, with some bird species becoming quiet and nocturnal animals suddenly becoming active. This is caused by them mistaking the eclipse for a new moon or by the sudden change in light.
