The blue moon is finally here. This phenomenon which happens every three years will occur on July 31. This term is used for an extra moon meaning that instead of the usual 12 moons a year will have 13. The last blue moon was in 2012 when certain time zones enjoyed two full moons in August and September.
In spite of the name we won’t actually see a blue moon on the sky. The natural color of the moon is a combination of grey and white as NASA pictures present it. If the moon has a different color it is due to events which occur on the surface of the Earth and not in space. An actual blue moon can be seen only when certain air compounds such as ash and pollutants enter in the atmosphere of our planet. Such a moon could be observed in exotic regions where there are volcanic areas.
For example when Krakatoa, the Indonesian volcano, erupted in 1883 the plumes of ash which ascended to the top of the atmosphere made the moon blue and even green sometimes. Scott Rowland, a volcanologist from the University of Hawaii said that even the sun seemed to have a lavender hue. He also remarked:
Such vivid red sunsets that fire engines were called out in New York, Poughkeepsie, and New Haven to quench the apparent conflagration.”
An average lunar cycle or one lunation has 29.53 days and a tropical year has nearly 365.24 days. As a result in a tropical year there are 12.37 lunations. According to the Gregorian calendar there is one full moon in each month of a year containing 12 months. However each calendar year has approximately eleven days more than the days which normally exist in twelve lunar cycles. As the extra days pile up every three years we have an extra full moon.
The Gregorian calendar is the most common time measurement used in the world. Since the moon orbits our planet less than our common calendar month indicates the day adds up outside the calendar. However time is measured by the force of the sky and the universe’s way of telling us about the remaining days outside the calendar is the blue moon which appears twice in a month.
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