The Waning Moon, observed this Monday (13), reduces the visible illuminated area of the satellite, marking one of the four main phases of the October 2025 lunar cycle. The phenomenon, which began at 3:12 PM, directly impacts tides and influences the behavior of various marine and terrestrial species. The lunar cycle, lasting an average of 29.5 days, also includes the New Moon (October 21) and Crescent Moon (October 29). Below, details on the effects and curiosities of the natural satellite.
The variation in lunar light during the Waning Moon, following the Full Moon on October 7, is easily noticeable on clear nights. The gradual reduction in nighttime illumination occurs due to the alignment between Earth, Moon, and Sun. This phase is less intense than spring tides, typical of the Full and New Moons.
- Main dates of the October 2025 lunar cycle:
- Crescent Moon: September 29, at 8:53 PM.
- Full Moon: October 7, at 12:47 AM.
- New Moon: October 21, at 9:25 AM.
- Crescent Moon: October 29, at 1:20 PM.
The Waning Moon, though less luminous, remains an accessible astronomical spectacle for all.
Effects on the oceans
Lunar gravity, the main driver of tides, has less intensity during the Waning Moon. Unlike spring tides, neap tides, typical of this phase, have reduced amplitude.
This phenomenon directly affects oceans, with changes in currents and coastal movements. Coastal regions, such as the Brazilian coast, notice subtle shifts in sea levels.
Impacts on wildlife
The decrease in nighttime light influences the behavior of marine and terrestrial species. Corals, mollusks, and sea turtles adjust their reproduction and feeding cycles to lower illumination.
Migratory birds may alter routes or movement schedules. Studies suggest the Waning Moon favors more reserved activities, such as seeking shelter.
Observational research indicates that reduced luminosity also affects nocturnal predators. Lower visibility can limit hunting, while prey benefit from the darkness.
Moon characteristics
The Moon, with a diameter of about 3,474 km, orbits Earth at an average distance of 384,400 km. Its elliptical orbit causes the distance to vary between 363,000 km (perigee) and 405,000 km (apogee).
The Moon’s synchronous rotation ensures only one face is visible from Earth. The so-called “far side” is illuminated by the Sun but can only be observed by space probes.
In the Southern Hemisphere, the Waning Moon appears with the illuminated part on the right, while in the Northern Hemisphere, on the left. This difference is due to the observation angle.
The Moon lacks an atmosphere, making its surface prone to meteoroid impacts, visible as craters.
Myths and science
Despite popular beliefs, there is no scientific evidence that the Waning Moon directly affects human mood or health. Studies debunk myths about changes in behavior or sleep during lunar phases.
Astronomical observation
The Waning Moon is ideal for stargazing due to lower nighttime luminosity. Amateur astronomers can take advantage of clear nights to observe the phenomenon with simple telescopes.