A blue moon is an astronomical event characterized by the occurrence of two full moons in a single month. Why, when, and how often this happens is a subject of extensive scientific study. In this article, we'll explain what a blue moon is, why it occurs, and reveal some other secrets. Curious about what a blue moon is? Keep reading to find out.
What is the blue moon
A blue moon is an event that occurs in certain years when there is more than one full moon per month . Although it's called a blue moon, it doesn't mean that this second full moon we're observing is actually blue. It has nothing to do with blue. It's simply the name given to the second full moon of the month, and it happens periodically.
During 2018, we had two blue moons. It's a rare event. In January, we had two full moons in the same month, as we did again in March. The second full moon of that month is the one considered a blue moon.
This is because the full moon occurs approximately every 29,5 days. This is what is considered a lunar month or lunar cycle, in which all parts of its phase can be observed . If the full moon occurs at the beginning of the month, there may be enough time for a second full moon at the end. For this to happen, it is necessary to continue studying the biodynamic patterns of the phases and cycle of our satellite.
Moons in March 2018
Let's analyze why a blue moon occurred in March 2018. Since February only has 28 days, it's quite short compared to other months. Therefore, if the full moon occurs at the beginning of the month, there's enough time for another one to be visible right at the end. The first full moon took place on March 2nd, and the second on the 31st, the very last day of the month. This second full moon is what we call a blue moon.
Not for this reason, it has the color blue or anything like that. When this event takes place, in the rest of the year 13 full moons are registered instead of 12. The same happens with the seasons of the year, in which some of them may have 4 instead of 3.
This seasonal blue moon is called a seasonal blue moon. Farmers consider this phenomenon so important that they mark it on their calendars. For those wondering when we'll see another seasonal blue moon, it will be on May 18, 2019.
What is its name if it is not blue
A name that refers to a color the satellite doesn't possess can lead to deception or error. There has been speculation over time as to why it has this name if it isn't blue. The most widely accepted theory to explain the name's origin is that it comes from Middle English . It was then called *belewe *, meaning "to betray." Later, it was called *blue *, meaning blue. It's possible that this name comes from a treacherous moon that decided to appear during the month it wasn't supposed to, rising early.
Although it's the most widely accepted theory, there are others that offer some differences. It's believed that the second full moon was once thought to bring bad luck and was therefore associated with the color blue, which represents sadness.
Whatever the origin, what you have to know is that, really, the second full moon that you have within the same month does not have a blue color.
Phases of the moon in different hemispheres
It does happen that we sometimes see a blue moon, but that doesn't refer to the event we just described. In certain circumstances, we can see the moon with a blue hue, and this is a very rare phenomenon.
What makes it look this color is the presence of dust or ash smoke in the upper layers of the atmosphere. These particles cause the red light to scatter slightly more and the blue light to stand out. However, the moon does not have to be full to be that color. This phenomenon has nothing to do with the fact that there are two full moons during the same month.
This phenomenon occurs thanks to volcanic eruptions in which large quantities of volcanic ash scatter red light from the atmosphere, making it appear bluer. This year, unless a large volcano erupts, we won't see a blue moon. A large forest fire can also allow us to see this beautiful color on our satellite, given the large amount of smoke and ash.
How often do we have a blue moon?
It's something many people want to know. Approximately every three years, two full moons can occur in the same month. This is easy to determine by counting a full lunar cycle of 29,5 days. If you count month by month, you'll find the month that can have two full moons. It's rare to have two blue moons in a single year, as we have this year.
To better understand how this phenomenon occurs, it's helpful to know how the lunar calendar works in relation to the solar calendar. As we know, the solar calendar is based on the time it takes our planet to orbit the Sun. That is, a year is divided into approximately 12 months and 365 days. However, lunar cycles last 29,5 days.
Therefore, the Metonic cycle is the time it takes for the lunar calendar to fully synchronize with the solar cycle. This is how their behavior repeats and coincides completely.
I hope that with this information you know more about the blue moon.