Blue micromoon and Antares visible this weekend

A rare celestial event, known as a blue micromoon, will be visible this weekend, offering a triple astronomical spectacle. The full moon will be both a "blue moon" and a "micromoon," while the bright star Antares will appear alongside it.

A blue moon occurs when two full moons happen within a single calendar month, an event that takes place roughly every two to three years. The first full moon of this month occurred on May 1. This second full moon is also classified as a micromoon because it will be at its farthest point from Earth in its orbit. The moon's orbit is not a perfect circle, and this weekend it will be approximately 252,360 miles, or 406,135 kilometers, away. This greater distance will make it appear slightly smaller and dimmer than an average full moon.

Gianluca Masi of The Virtual Telescope Project, which will provide a live webcast from Italy, said the micromoon will appear about 6 percent smaller and 10 percent dimmer than an average full moon. He noted these differences are subtle enough that most casual observers likely will not notice them. The phenomenon is the opposite of a supermoon, which occurs when a full moon is at its closest approach. A recent...