Black moon: A celestial event that occurs rarely
The first solar eclipse of 2022 occurred on April 30 this year. This partial eclipse coincided with a rather rare lunar event, known as Black Moon. Have you ever heard of this phenomenon? Well, when a second new moon occurs in a month, it is known as black moon. It is very similar to blue moon, which is the second full moon of a month. This is also not-so-common an occurrence in the solar system. That is why we have this figurative expression ‘Once in a Blue Moon’ which implies the rarity of something or an event. In order to understand why and when black moon occurs, we need to know about how a moon functions and its calendar.
Lunar cycle: A brief snapshot
The moon is a natural satellite. However, the silver light that we see it emitting, is borrowed from the sun. Just as Mother Earth revolves around the sun, the moon also orbits around the earth. While the time taken by earth to complete one cycle of movement around the sun is 365 days, the moon takes about a month to travel around the earth. To be precise, the time taken to complete one orbit around the earth is 29.5 days and this period is considered to be one lunar cycle. Actually, the concept of month emerged from this phenomenon. Just like the earth, the moon has two sides, with half of it experiencing day and the other half in darkness at any point of time.
Every night, we see the moon changing its shape and size. Do you know why? Well, that’s because it goes through various phases during a lunar cycle. In fact, the line that divides the day and night of the moon gives different impressions of this natural satellite from different angles of the earth. The lunar cycle begins with the new moon phase, when it appears dark. This is because, during this phase, the earth faces the unlit side of the moon. This is the only time the moon is between the earth and the sun.
As the moon continues its revolution around the earth, its visibility increases gradually. This is how it reaches the full moon phase when we can view it completely. Typically, we experience one new moon at the beginning of the month and one full moon in the middle of a month.
Black Moon: Why does it occur?
In the span of a year, we are supposed to experience 12 new moons and 12 full moons. However, the duration of a lunar cycle is slightly shorter than a month, which is typically 30 or 31 days. That is why we sometimes get an extra new moon, also called Black Moon: One at the beginning of the month and another at the end. This is what exactly happened on this 30th April. The second new moon that we experienced that day was at a distance of 395,380 kms from the earth. The same theory applies to full moon too, which sometimes occurs twice a month and the second full moon.