Rare super blue moon of August 2023 rises this weekon August 30th. The term, 'supermoon' more a product of branding than astronomy, was actually coined by an astrologer. It refers to a full moon that occurs when the moon is at or near its closest point to Earth in a given orbit, known as perigee.
At precisely 12 noon ET on the fifth Wednesday of August, the moon will reach perigee, coming closest to Earth at a distance of 221,942 miles (357,181 km). Then, 9 hours and 36 minutes later, the moon will officially reach its full phase. Although a full moon technically lasts for just an instant, this moment is too brief to be noticed by the naked eye.
For about a day before and after this moment, most people will describe the almost fully illuminated moon as "full." The shadowed edge is so narrow, changing in width so gradually, that it becomes difficult for the unaided eye to discern its presence or orientation.
Adding to its "supermoon" designation, this upcoming full moon holds the distinction of being the second to grace the month of August; the first appeared on August 1st. Consequently, the second full moon arriving on the 30th will also be labeled a "Blue" moon. In essence, what we're in for is a celestial event dubbed a "Super Blue Moon."
Nevertheless, unless unique atmospheric circumstances such as suspended dust, ash, or smoke intervene, the moon will maintain its typical yellow-white appearance rather than turning blue. Regardless, fueled by the exaggeration often found in mainstream media, a great number of people will probably anticipate catching a glimpse of this substantial late-summer moon.
If observing the full moon sparks your interest, our comprehensive binoculars guide can steer you toward excellent wide-angle options, ideal for capturing more expansive sections of the lunar landscape. Alternatively, if your curiosity leans toward scrutinizing the moon's features up close, our telescopes guide is at your service to aid you in selecting the necessary equipment.
For those with aspirations of capturing images of our celestial companion or the nocturnal expanse, peruse our manual on moon photography. Additionally, explore our top recommendations for cameras tailored to astrophotography, as well as our selection of prime lenses suitable for capturing the wonders of the night sky.
A blue moon in the sky with many stars
However, there's also a downside: A full moon closely aligning with perigee signifies that around August 30th, the tidal range will deviate significantly from the norm. Low tides will be exceptionally low, while high tides will surge unusually high, potentially resulting in minor coastal inundation.
This intensified tidal event is referred to as a perigean spring tide. The term "spring" originates from the German word "springen," meaning to "spring up." It is not, as commonly mistaken, connected to the spring season. Spring tides occur each month during the full and new moon phases.
During these periods, the moon and the sun align with the Earth, amplifying their combined tidal effects. (The sun contributes slightly less than half of the moon's tidal force.) Conversely, "neap tides" manifest during the first and last quarter moon phases when the moon's influence counters that of the sun, resulting in weaker tides.
Tidal force varies inversely with the cube of the distance between objects. On Wednesday, the moon will be approximately 14 percent closer at perigee compared to apogee. Consequently, during the August 30th spring tides, the moon will exert 48 percent more tidal force than the spring tides near apogee, which occurred two weeks earlier on August 16th.
Should a substantial storm or hurricane be present offshore, combining with the already elevated water levels, the outcome could encompass turbulent seas, shoreline erosion, and significant flooding. We can only remain hopeful that these meteorological conditions do not transpire this year. However, it's worth noting that the conventional peak of the Atlantic hurricane season is less than two weeks away, on September 10th.
In the past, a full moon coinciding with perigee held the straightforward classification of a "perigean full moon." This term, however, garnered minimal attention and lacked any significant excitement.
In the present day, it appears that every instance of a full moon aligning with perigee is now dubbed a "supermoon." Certain news presenters, seemingly in an endeavor to maintain audience interest, characterize this event as "rare," even though the truth is that a full moon occurring within hours of its perigee arrival isn't all that uncommon.
To be precise, this conjunction transpires roughly every 413 days on average. Following the upcoming Wednesday, the subsequent occurrence is slated for October 17, 2024.
Curiously, the full moon on August 1st, transpiring around 11 and a half hours before perigee, and the following month's full moon on September 29th, occurring nearly 33 hours after perigee, are also embraced within the "supermoon" category. This classification seems to stem from their proximity to the moon's closest approach to Earth, specifically within the top 10 percent of the nearest full moons throughout a given year.
As a result, we now find ourselves facing not just one, but four "supermoons" in most years. Depending on the year, this count could dwindle to two or escalate to as many as five. The real question emerges: Just how extraordinary or "super" is this phenomenon, after all?
A blue moon in the sky above some tree branches
While the upcoming moon on Wednesday will indeed hold the distinction, as proposed by the Observer's Handbook of the Royal Astronomical Society of Canada, of being the "largest full moon of 2023," its apparent size will only be 14% larger compared to a full moon at its farthest point from Earth, known as apogee. Nonetheless, this fluctuation in the moon's distance doesn't readily manifest for observers gazing at it directly.
Hence, stepping outside on Wednesday night with the anticipation of witnessing something extraordinary might lead to disappointment. As a customary practice, numerous images flood the internet before a "Supermoon" event, showcasing extraordinarily sizable full moons. These photographs are invariably captured using telephoto lenses, creating an illusion of an astonishingly large moon in the sky.
In reality, without prior knowledge of the moon's proximity, most individuals would likely not discern any disparity between Wednesday's full moon and any other typical full moon. Yet, with the introduction of the "supermoon" notion, these very same individuals will venture outside, cast their gazes upward, and assert that the moon does indeed appear substantially larger than usual. This phenomenon mirrors the way the phrase "emperor's new clothes" has become synonymous with logical fallacies.
The issue of the moon's radiance also comes into play. Numerous websites tout the "supermoon" as appearing "30 percent brighter than regular full moons." However, this translates to an exceedingly modest increase of less than three-tenths of a magnitude. Consequently, the moonlight on the upcoming Wednesday night will not exhibit an exceptionally heightened brightness.
Despite this, it's probable that there are individuals who anticipate a remarkably dazzling full moon that evening. In the context of the June 2013 "supermoon," a friend of mine shared her expectation that the moon would be 'noticeably brighter,' drawing a comparison to three-way light bulbs; she believed the moon's luminosity would be akin to turning up moonlight by a notch. Regrettably, the reality was quite different, as the moon's luminance remained indistinguishable from the nights that preceded it.
On Wednesday, the moon's potential to seem exceptionally large arises from a distinct phenomenon. When the perigee moon aligns itself close to the horizon, it can adopt an absolutely colossal appearance.
This occurs when the renowned "moon illusion" blends with reality, resulting in a truly breathtaking spectacle. For reasons that continue to elude both astronomers and psychologists, a moon hanging low in the sky appears remarkably vast when juxtaposed with trees, structures, and other foreground elements.
The fact that Wednesday's moon will be notably nearer to Earth than usual will further intensify this enigmatic effect. Consequently, a perigee moon, whether rising in the east during sunset or descending in the west at sunrise, might create the illusion that the moon is so close you could almost reach out and touch it. To experience this firsthand, you can ascertain the moonrise and moonset times for your specific location by consulting the U.S. Naval Observatory website.
A full moon's position lies directly opposite to the sun in the sky. Interestingly, just three days prior to the moon reaching this juncture, the planet Saturn will achieve opposition to the sun, positioning itself similarly in the sky. Consequently, on Wednesday night, Saturn will make an unexpected appearance alongside the moon, situating itself approximately 5 and a half degrees to the upper right of the lunar orb.
It's worth noting that Saturn, unlike our nearby neighbor, resides at a much greater distance. To be precise, it will be positioned 814.6 million miles (1.31 billion km) away from Earth, equating to a light travel time of 73 minutes.
The resplendent planet will emanate a calm yellow-white luminosity. Its iconic ring system, tilted 9 degrees toward Earth, will be discernible, particularly through high-powered binoculars or compact spotting scopes with magnifications of at least 25x. Regardless of your personal perception of Wednesday's full moon, the Space.com team extends warm wishes for clear, moonlit skies to all skywatching enthusiasts.