Understanding April’s ‘Micromoon’

The moon’s actual size remains consistent. Since its formation billions of years ago, its average diameter has remained steady. To provide context, this distance is shorter than the span from Los Angeles to New York. As a comparison, if the Earth were the size of a nickel, the moon would be comparable to a coffee bean. However, the moon’s apparent size can vary, and this Saturday, April 12, it will appear smaller than usual, a phenomenon known as a micromoon. Here’s what to keep in mind.

The moon’s perceived size can change significantly from night to night. The , or moon illusion, can make it appear especially large when it’s near the horizon, only to seem smaller as it rises higher in the sky. However, this is an optical illusion. You can test this by extending your arm, closing one eye, and holding up your index finger. Your fingernail will appear to be about the same size as the moon, regardless of how large or small the moon looks. This is because your brain unconsciously compares the moon to objects like houses and trees on the horizon, making it seem larger. Higher in the sky, the moon is dwarfed by the vastness of space, leading your mind to believe it has shrunk.

The micromoon is a separate phenomenon. The moon’s average distance from Earth is 238,855 miles, but this distance fluctuates. The moon follows an elliptical orbit around Earth, with its closest point (perigee) being about 224,000 miles and its farthest point (apogee) being 251,650 miles. When the moon is at perigee, it appears larger, creating a , where the moon looks 7% larger and 15% brighter than usual. At apogee, where the moon will be this weekend, it appears 14% smaller and 30% dimmer, resulting in the illusion of the .

This micromoon is also called a , though its name doesn’t refer to its color. (This contrasts with the , which occurs during a lunar eclipse when Earth’s shadow falls on the moon. During this event, the Earth’s atmosphere scatters blue wavelengths of sunlight but allows red wavelengths to pass through, giving the moon a reddish tint.) The pink moon is simply a traditional name for the April full moon, named after the spring flowers that bloom during this time.

The pink micromoon will rise at dusk this Saturday, reaching its . Space enthusiasts will be observing it, similar to how they view a supermoon. However, not everyone is equally impressed. As astronomer Neil deGrasse Tyson pointed out: “If last month’s Full Moon were a 16.0 inch pizza, then this month’s ‘Super’ Moon would be 16.1 inches. I’m just saying.” By that logic, the micromoon would be a 13.76-inch pizza. Enjoy it regardless.

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