In a rare astronomical event, August 2023 will offer stargazers the opportunity to see two supermoons, coupled with the appearance of an elusive blue moon.
A supermoon takes place when a full moon’s orbit brings it closest to our planet. As NASA explains, the moon’s orbit around the Earth isn’t perfectly circular but rather shaped like an elongated oval, or an ellipse. This causes the moon to oscillate between closer and farther distances from our home planet as it completes its orbital cycle.
The furthest point the moon travels from Earth is referred to as the apogee, where the moon sits an average distance of 253,000 miles away. Conversely, the point where the moon is closest to the Earth is known as the perigee, where the moon is roughly 226,000 miles from Earth.
Close approach causes supermoons
It’s at the perigee stage that a supermoon occurs, when the full moon aligns with the moon’s closest approach to Earth. When observed from the Earth, supermoons tend to appear larger and brighter than a regular full moon, although the difference is slight.
This year’s supermoon cycle is particularly special because the four occurrences are happening consecutively. The first of this year’s supermoons appeared on July 3, and the final supermoon of this series will occur on September 29.
What is a blue moon?
The term blue moon does not refer to the moon’s color but rather to its frequency. A blue moon is the name given to the second full moon that occurs within a single calendar month.
Because a full moon generally appears every 29 days, and as most months are longer than this, comprising 30 or 31 days, it’s possible for two full moons to fall within the same month on occasion.
Blue moons are infrequent events that usually take place approximately every two and a half years. The most recent blue moon was visible on August 22, 2021.
This year, the month of August is set to play host to two full moons. Excitingly, both of these are also supermoons, according to the Old Farmer’s Almanac.
The Sturgeon Moon
The first of these, also known as the Sturgeon Moon, will occur on Tuesday, August 1, with the moon reaching its peak at 2:32 p.m.
The name “Sturgeon Moon” comes from some Native American groups, primarily those in the Great Lakes region of North America, who found that sturgeon were most abundantly caught during this month.
Sturgeons are prehistoric-looking fish that have been around for over 130 million years. Many species of this fish have developed globally, with some finding a habitat in the Great Lakes.
Different cultures and societies have different names for the full moons throughout the year. For example, for Algonquins, the August full moon is also referred to as the “Grain Moon” due to the prevalence of grains during this time.
Other names for the August full moon include the Green Corn Moon, the Barley Moon, or the Fruit Moon, often reflecting the various crops and foods that become ripe and ready to harvest during this time of year.
Closest full moon this year
August will wrap up with the appearance of a blue moon on Wednesday, August 30, reaching its peak at 9:36 p.m. This moon is not only significant for being the second full moon of the month (a blue moon), but is also classified as a supermoon.
This particular blue moon will be the closest full moon to Earth for the entire year, adding an extra layer of astronomical intrigue.
Overall, this August promises to be a magnificent time for astronomers and stargazers alike. For anyone planning to observe these lunar events, it’s best to find a location away from city lights for the clearest view. Also, using a telescope or even a good pair of binoculars can enhance the experience.
For supermoons, since they rise at sunset, looking for a location where you can see the horizon clearly will help you get the best view.
More about supermoons
A supermoon is a natural phenomenon where the full moon coincides with the moon’s closest approach to Earth in its elliptical orbit, a point known as perigee. The effect of this coincidence creates a visual spectacle, making the moon appear substantially larger and brighter than usual.
Causes of a supermoon
A supermoon event results from the unique alignment of the Earth, moon, and sun. The moon follows an elliptical orbit around the Earth, which means its distance from our planet changes throughout the month.
At its farthest point, known as apogee, the moon stands around 405,500 kilometers away. Conversely, at perigee, the moon’s closest point to Earth, the distance decreases to approximately 363,300 kilometers.
When the moon reaches perigee at the same time as it becomes a full moon, the result is a supermoon. This precise alignment creates a slightly larger and brighter moon, with increases of up to 14% in apparent size and up to 30% in brightness compared to a micromoon, the term for a full moon at apogee.
History and naming of the supermoon
The term “supermoon” traces its roots back to astrology rather than astronomy. Astrologer Richard Nolle first coined the term in 1979 to refer to a new or full moon that occurs when the moon is within 90% of its closest approach to Earth.
However, astronomers prefer the term “perigee-syzygy” to describe this celestial alignment, where “syzygy” refers to the alignment of three celestial bodies, in this case, the sun, Earth, and moon.
The occurrence of a supermoon carries significance in various cultures. Many indigenous cultures ascribe special meaning to supermoons, and their appearance often features in folklore and mythology. In modern times, supermoons tend to draw large numbers of spectators due to their increased brightness and size, offering unique opportunities for night-time photography and observation.
Frequency and prediction of supermoons
Supermoons are not particularly rare phenomena, occurring roughly three to four times per year. Their predictability stems from the consistent nature of the moon’s orbit and the regularity of the lunar cycle, which spans 29.5 days from one full moon to the next. Scientists can accurately predict the occurrence of supermoons years in advance using mathematical models.
Not all supermoons are equal, though. The size and brightness of a supermoon can vary depending on the exact distance of the moon at perigee and the amount of light it reflects from the sun.
In summary supermoons are a fascinating celestial phenomenon rooted in the intricate dance of celestial mechanics. Their larger, brighter appearance compared to typical full moons has drawn interest from cultures worldwide and continues to captivate observers and photographers alike.
The predictable yet variable nature of supermoons invites ongoing observation and study, reinforcing the enduring allure of our celestial companion, the moon.
More about blue moons
A Blue Moon refers to an unusual occurrence within our lunar calendar, most commonly defined as the second full moon within a calendar month. Although the term “Blue Moon” suggests a change in color, a Blue Moon retains its normal whitish hue. This article will delve into the origin of the term, how it’s calculated, its frequency, and cultural significance.
Origin and definition of the blue moon
The term “Blue Moon” dates back to at least the 16th century in English literature, initially symbolizing absurdity and improbability. In modern usage, the phrase stands for a relatively rare event, hence the saying, “once in a blue moon.”
The widely accepted definition, indicating the second full moon in a calendar month, became popular following an error in an article in “Sky & Telescope” magazine in 1946.
This definition stemmed from a misinterpretation of the Maine Farmer’s Almanac, which originally defined a Blue Moon as the third full moon in a season that has four full moons instead of the usual three. Both definitions are in use today, but the former has more widespread acceptance.
Calculation and frequency of blue moons
Blue Moons appear based on the incongruity between our calendar system and the lunar cycle. The lunar cycle, the period from one full moon to the next, spans approximately 29.5 days, while most months have 30 or 31 days. This discrepancy allows for two full moons to occur within the same month.
Based on the more common definition, a Blue Moon can occur, on average, once every 2.5 to 3 years. In terms of seasonal Blue Moons, they occur roughly once every 2.5 years as well. The year 1999 famously had two Blue Moons: one in January and one in March, with no full moon in February.
Despite no visible difference from regular full moons, Blue Moons hold cultural significance due to their rarity. They are often subjects of folklore, songs, and expressions symbolizing infrequent events or occurrences. The phrase “once in a blue moon” represents something that doesn’t happen very often.
From a scientific standpoint, Blue Moons offer no specific value as they are a result of our calendar system rather than an astronomical event. Nevertheless, they provide an opportunity to engage the public in lunar observation and an appreciation for the rhythms of our natural world.
A Blue Moon, while not visually distinct, carries a unique charm due to its rarity and the myths that surround it. It is a reminder of the complex interplay between our calendar, celestial mechanics, and cultural imagination. Despite being a product of human time-keeping, the occurrence of a Blue Moon can prompt renewed interest in the night sky and the intriguing patterns that unfold in it.