The moon, like many children, goes through phases. As the surface of the moon becomes more lighted each day on the way to full, it’s “waxing.” “To wax” means to increase in size gradually, and used to be a frequent synonym for “grow,” according to the The Oxford English Dictionary.

May affect blood pressure Their heart rate and blood pressure were both lower during full and new moons. Plus, their heart rates returned to normal levels more quickly during full and new moons. In this study, researchers concluded that humans were more physically efficient during full and new moons.

Someday, you might see a true blue-colored moon in the sky. Blue-colored moons are rare – aren’t necessarily full – and happen when Earth’s atmosphere contains dust or smoke particles of a certain size, slightly wider than 900 nanometers. Particles of this size are very efficient at scattering red light.

A “gibbous” moon is any moon that appears more than half lighted but less than full. You’ll see a waxing gibbous moon between a first quarter moon and full moon. The word gibbous comes from a root word that means hump-backed.

It takes around 29.5 days to move through the eight Moon phases.

First quarter: The moon is 90 degrees away from the sun in the sky and is half-illuminated from our point of view. We call it “first quarter” because the moon has traveled about a quarter of the way around Earth since the new moon.

Waxing means it’s getting bigger while waning means it’s getting smaller. “So, you’ve got to look at this whole process,” he said. “It takes about 29 and a half days for the moon to go all the way around the earth—that’s why you can have two full moons in the same month.”

One quick way to tell if a moon is in a waxing or waning phase is which side of the moon is the shadow on. If the shadow is on the right, like it is today, we are in a waning phase. If the shadow is on the left, then we are waxing and heading towards a full moon. An easy way to remember is to rhyme bright and right.