There is a conversation happening between the Moon and the ocean. Right now, somewhere on Earth, a coastline is flooding or draining, pulled by a force that originates 384,000 kilometres away.
The Moon does this. Quietly, reliably, without interruption.
But the Moon is not always the same Moon. It arrives in different sizes, different colours.
The Blood Moon
A blood moon happens during a total lunar eclipse, when the Earth moves directly between the Moon and the Sun, casting its shadow across the entire lunar surface. The Moon should go dark. Instead, it turns red.
What you are seeing is every sunrise and every sunset happening simultaneously, projected onto the Moon. The Earth's atmosphere bends and filters sunlight around the curve of the planet, stripping out blue wavelengths and leaving only the reds and oranges — the same colours that light the horizon at dusk. That filtered glow reaches the Moon and bounces back to us, rust-coloured and strange, for as long as the eclipse lasts.
Because a blood moon is always a full moon in total eclipse, the tidal pattern holds: the Earth, Sun and Moon are aligned, and the spring tide effect is in play. The sea runs high beneath the red light.
The Supermoon
The Moon's orbit around Earth is not a perfect circle. It is an ellipse — a gentle oval — which means the Moon is sometimes closer to us than at other times. When a full moon coincides with the Moon being near its closest point to Earth (what astronomers call perigee), you get a supermoon.
It appears a little larger in the sky, a little brighter. Not dramatically so — the difference is subtle, but the tidal effect is more pronounced. A closer Moon means a stronger gravitational grip on the ocean. Coastal flooding becomes more likely during a supermoon high tide, particularly when storms are also in the picture.
The sea knows when the Moon is close and leans toward it, just a little more.
The Blue Moon
A blue moon is rarely blue, almost never dramatic, and entirely about counting.
The most widely used definition: a blue moon is the second full moon in a single calendar month. Since the lunar cycle runs about 29.5 days and most months run 30 or 31, a second full moon occasionally squeezes in before the month turns over. It happens roughly every two and a half years.
There is an older definition, too — a blue moon as the third full moon in a season that contains four, rather than the usual three. Either way, the name points to rarity rather than appearance.
Its tidal influence is no different from any other full moon.
The New Moon
You cannot see a new moon. It sits between the Earth and the Sun, its illuminated face turned away from us entirely. The night sky is at its darkest.
And yet, this is when the ocean is at its most awake.
During a new moon, the Sun, Moon, and Earth fall into alignment. Their gravitational forces combine, amplifying each other. The result is what sailors and scientists call a spring tide — named for the way the water seems to spring forward, surging higher and retreating lower than usual.
The Full Moon
Astronomically, a full moon occurs when the Earth sits between the Moon and the Sun. The Moon is fully lit from our perspective, and crucially, the three bodies are again in alignment. This means another spring tide: another surge of amplified water, another extreme push and pull along every coast.
The full moon also brings its particular subset of characters.
The physics
here's a beauty in the powerful physics of tides. The Moon's gravity reaches across the void and grips the Earth. Not just the surface it faces, but all of it. The oceans, being fluid and willing to move, respond by pooling: bulging outward on the side closest to the Moon, and counterintuitively, also on the side farthest away.
These two bulges are the high tides. As Earth rotates through them, most coastlines pass through each bulge roughly once every twelve hours, producing two high and two low tides per day.
The high tides never line up exactly with the Moon's position. Because Earth rotates faster than the Moon orbits, the bulges always run a little ahead of the Moon itself — a permanent, planetary lag between cause and effect.