According to the U.S. Naval Observatory, there will be a full moon on August 30th when the Earth is positioned between the sun and the moon. The moon will reflect the greatest sunlight onto the Earth.
Compounding this spectacular event are a number of other unusual factors. This will be the second full moon in August giving it the designation “Blue Moon”. The most recent blue moon occurred in October 2020. Despite the name, the moon probably won’t appear to be blue. The term originates from a 16th century expression referring to something that rarely happens.
However, the moon has been known to appear blue when there is major disruption to the Earth’s atmosphere, such as following a volcano. According to NASA, blue moons were common following the eruption of the Indonesian volcano Krakatoa in 1883.
“The key to a truely blue moon is having lots of airborne particles slightly wider than the wavelength of red light (0.7 micron) – and no other sizes present,” the US space agency noted in a blog post. “This is rare, but volcanoes sometimes spit out such clouds, as do forest fires.”
There have been several major wildfires in 2023, including significant fires in Canada and the Mediterranean. “If any of those fires produce ash or oily-smoke containing lots of 1-micron particles, the Blue Moon there could be blue,” NASA wrote. “More likely, it’ll be red. Indeed, red, Blue Moons are far more common than blue Blue Moons.”
A Supermoon or Perigee Full Moon is a full moon that occurs when the center of the moon is less than 360,000 kilometers (ca. 223,694 miles) from the center of Earth. The technical term for a Supermoon is perigee-syzygy of the Earth-Moon-Sun system. In astronomy, the term syzygy refers to the straight-line configuration of three celestial bodies. This 8/30 full moon will coincide with perigee, the point in the moon’s orbit when it is closest to Earth — about 221,942 miles away. The moon will also make a close approach to the planet Saturn. Between 7:30 p.m. on August 30th and 6:30 a.m. on August 31st, this “Blue Super Moon” will appear about 17% bigger and 30% brighter than the faintest moon of the year. The most recent Super Blue Moon was in December 2009.
The combination of the near proximity of the moon and the full moon phase results in the greatest difference between high and low tide. The gravitational forces of the moon and the sun combine to pull the ocean’s water in the same direction. These tides are known as spring tides or king tides. Supermoons lead to an additional 2 inches larger variation than regular spring tides, called perigean spring tides.
The best time to enjoy a Super Full Moon, or any other Full Moon, is just after moonrise, when the moon is close to the horizon. Just before moonset is also a good time. A live stream of the supermoon in August over the skyline of Rome will be available to watch on the official YouTube channel of the Virtual Telescope Project. The next blue supermoon will happen in August 2032.
Celebrate the Blue Moon locally at the Seneca Polo Club for the Blue Moon Club Chukkers. Wednesday August 30th. The polo game starts at 7:00 p.m. Spectators are welcome. Tailgate or bring a dish. Grilling after the game. Peak moon viewing at 9:36 p.m. 20760 White’s Ferry Rd. Poolesville, MD. Suggested donation for admission.