Get set for a rare blue micromoon this weekend. It’s when a blue moon that’s also the most distant and smallest-looking full moon of the year rises. The brilliant star Antares will photobomb Sunday’s spectacle for a celestial three-for-one. A blue moon occurs every two to three years when a second full moon squeezes into a single month. May 1 saw this month’s first full moon. The upcoming full moon will be farther from Earth than usual at a distance of 252,360 miles. That will make the moon seem a bit smaller and dimmer.