Blue moon tonight: How to see the largest full moon of 2023

The final throes of August will provide stargazers with the biggest and brightest full moon of the year. The phenomenon, commonly known as a supermoon, occurs when the perigee (the point in the lunar orbit when our satellite is closest to Earth) coincides with the full moon phase. From the point of view of the terrestrial observer, the moon will appear slightly larger (up to 7%) and brighter (up to 15%) than usual.

At around 357,300 kilometers (222,015 miles) away from Earth, in contrast to the 384,400 kilometers (238,855 miles) that on average separate the two stars, the supermoon of August 30 will officially turn full at 9:36 p.m. ET (7:36 p.m. CST / 2:36 a.m. on Thursday in the U.K.) and will traverse the sky in an east-west direction for the rest of the night, until it disappears at dawn. The phenomenon will continue to be visible to a lesser extent during night of August 31.

Although the supermoon will reach its highest point in the sky around midnight, the best time to capture photos or videos occurs earlier Wednesday, just after it crests the horizon. In addition to the ocher hue it takes on due to the scattering of light in the atmosphere when it is at a lower altitude, the presence of other objects such as buildings, mountains, or trees causes an optical effect that increases its size further.

Blue moon or supermoon?

Harvest moon, corn moon, blue moon, supermoon… the names given to the full moons that occur each month do not describe a particular astronomical phenomenon, nor do they encompass any scientific concept. They are popular expressions, derived from the mystery surrounding the Earth’s natural satellite and the relationships that, from the perspective of different ancient cultures, were established between the weather, the seasons, and agriculture based on the periodic appearance of the satellite. The names of the most well-known moons today originate from the Maine-based Farmer’s Almanac, a publication that during the 1930s compiled the various nicknames given to the moon throughout the year by Native American peoples, a tradition that NASA has recently reinstated. Hence, for example, the August moon is known as a harvest, corn, or hunter’s moon.

The full moon on August 30 is both a supermoon and a blue moon. While the term supermoon gained popularity in the 1980s to arbitrarily name the coincidence between the full moon and the perigee, blue moon is an expression that simply describes the second full moon of the same month. Despite its name, during the blue moon phase our satellite will not look a different shade than usual. The only anomaly — taking into account that the lunar cycle lasts 29 days and the months in the Gregorian calendar extend from 28 to 31 days — will be its appearance for the second time in the same month, a phenomenon that is repeated approximately every 2.5 years.

Sign up for our weekly newsletter to get more English-language news coverage from EL PAÍS USA Edition