A blue micromoon will grace the skies this weekend, offering a rare celestial spectacle that won’t occur again until the end of 2028. The event combines two astronomical phenomena: a blue moon (the second full moon in a single month) and a micromoon (a full moon at its farthest point from Earth).
Core Facts
The blue micromoon will peak at 4:45 a.m. ET on May 31, though it will appear full from the night of May 30. Unlike its name suggests, the moon won’t appear blue but will be slightly smaller and dimmer due to its distance of 252,360 miles from Earth. This contrasts with a supermoon, which occurs when the moon is closer to Earth, such as the recent supermoon at 225,130 miles away.
Visibility and Viewing Tips
The blue micromoon will be visible to the naked eye, weather permitting, but stargazers in the Southern Hemisphere—particularly in Argentina, Chile, New Zealand, and eastern Australia—may see the moon obscure the bright star Antares in the constellation Scorpius. For optimal viewing, observers should seek dark skies away from city lights. Other planets like Venus, Jupiter, Mars, and Saturn will also be visible in the sky during this time.
Astronomical Context
A blue moon occurs roughly every two to three years due to the lunar cycle’s 29.5-day duration, which occasionally allows two full moons in a single month. The term “blue moon” originates from a 16th-century expression meaning something rare, and the phrase “once in a blue moon” persists today. There are two types of blue moons: calendar blue moons (the second full moon in a month) and seasonal blue moons (the third full moon in a season with four full moons). The next seasonal blue moon is expected in May 2027.
Scientific Insights
The Virtual Telescope Project will stream live images of the blue micromoon, captured by its robotic telescopes. Astronomers note that the moon will appear 6% smaller and 10% dimmer than an average full moon, though these differences may be subtle to most observers. The moon’s elliptical orbit causes these variations in size and brightness.
Historical and Cultural Significance
The last blue moon occurred in August 2023, and the next one won’t appear until December 31, 2028. The event has cultural significance, as blue moons have been referenced in folklore and idioms for centuries, symbolizing rarity and uniqueness.