The names “blue moon” and “pink moon” are fascinating and often misunderstood terms that have more to do with folklore and traditions than the actual color of the moon. Let’s delve into these terms, their origins, meanings, and the scientific facts behind them.
Blue Moon
What is a Blue Moon?
The term “blue moon” does not refer to the moon’s color but is used to describe a rare occurrence in the lunar calendar. There are two main definitions of a blue moon:
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Seasonal Blue Moon: This occurs when there are four full moons in a single astronomical season (the period between a solstice and an equinox, or vice versa). The third full moon in this sequence is called the blue moon. This definition dates back to the Maine Farmer’s Almanac.
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Calendar Blue Moon: More commonly known today, this definition refers to the second full moon in a calendar month that has two full moons. This interpretation gained popularity after a 1946 article in Sky & Telescope magazine mistakenly defined it this way, and it stuck.
Why is it Called a Blue Moon?
The term “blue moon” has been around for centuries, but its exact origin is unclear. Some sources suggest it could be derived from the old English word “belewe,” meaning “to betray,” as an extra moon in a season could disrupt the usual timing of religious festivals. Alternatively, it might come from the expression “once in a blue moon,” meaning a rare event, reinforcing the idea of its infrequency.
Does the Moon Ever Look Blue?
While a blue moon does not refer to the moon’s color, the moon can appear blue in rare circumstances. This phenomenon occurs when there are particles in the Earth’s atmosphere, such as after a volcanic eruption or a major forest fire, that scatter red light and allow blue light to pass through. Such events are indeed rare and unrelated to the calendrical definition of a blue moon.
Pink Moon
What is a Pink Moon?
The “pink moon” is a name from Native American tradition, particularly the Algonquin tribe, and refers to the full moon in April. This name is part of a broader practice of naming each full moon throughout the year based on natural events and agricultural cycles.
Why is it Called a Pink Moon?
The pink moon is named after the herb moss pink, or wild ground phlox, which is one of the earliest widespread flowers of spring in North America. The pink moon signifies the time of year when these flowers bloom, rather than the moon’s color.
Does the Moon Ever Look Pink?
Like the blue moon, the pink moon does not actually appear pink. The moon’s color can vary based on atmospheric conditions and its position in the sky. When the moon is low on the horizon, it can appear more orange or red due to the scattering of light through the Earth’s atmosphere, but it does not turn pink.
Other Cultural Moon Names
The blue and pink moons are part of a rich tradition of naming moons that can be found in various cultures around the world. These names often reflect seasonal changes, agricultural activities, and cultural events.
Examples of Other Moon Names
- Wolf Moon (January): Named for the howling of wolves during midwinter.
- Snow Moon (February): Named for the heavy snows that typically fall in this month.
- Harvest Moon (September/October): The full moon closest to the autumnal equinox, aiding farmers in harvesting crops.
- Hunter’s Moon (October/November): Following the harvest, this moon was named for the time to hunt and store provisions for winter.
Scientific Perspective on Moon Colors
The moon can appear in various colors due to several factors, but these are usually temporary and not related to the calendar definitions of blue or pink moons.
Atmospheric Effects
- Rayleigh Scattering: This causes the blue sky and can make the moon appear more reddish or orange when it is low on the horizon.
- Volcanic Eruptions: Ash and particles can scatter light, occasionally making the moon look blue.
- Wildfires: Smoke and particulates can also alter the moon’s color, sometimes giving it an unusual hue.
Observational Conditions
- Eclipses: During a lunar eclipse, the moon can take on a reddish color, known as a “blood moon.”
- Pollution: Urban pollution can affect the color of the moon as seen from the ground.
Conclusion
The names “blue moon” and “pink moon” capture the imagination and evoke a sense of wonder, but they are not indicators of the moon’s actual color. Instead, these names are steeped in cultural, historical, and folkloric traditions that reflect the human desire to connect celestial events with earthly experiences. Understanding the origins and meanings of these terms helps us appreciate the rich tapestry of language and tradition surrounding our natural world. While the moon may not turn blue or pink in reality, the stories and names we attribute to it continue to inspire curiosity and awe.