As the next full moon nears, a more rare new moon will grace the New Year's Eve sky, marking the end of 2024 — the black moon. Tuesday's black moon is a rare celestial phenomena that happens roughly every 29 months or longer. The last one occurred in August of 2022 and the next won't come again until May of 2026.

That's because a black moon is the term for the second new moon to fall in a single calendar month, and new moons appear invisible to the naked eye from Earth. While new moons happen throughout the year, two new moons only fall in a single calendar month about once every 29 months, according to the Old Farmer's Almanac.