Full Moon Rise Finder — Red Lunar Rising

What this tool does

Red Lunar Rising calculates the exact evenings when a full moon rises within ten minutes of the sun setting at your chosen location. This alignment — sometimes called a "moonrise sunset" — happens only a handful of times per year at any given spot on Earth, and it produces one of the most striking sights in the night sky: a giant, often amber-colored moon climbing over the horizon on one side of the sky while the sun sinks below the horizon on the other. Enter any U.S. city and we'll search up to three years ahead using precise astronomical calculations, then let you add the date straight to your calendar so you don't miss it.

What is a full moon?

A full moon occurs when the Earth sits roughly between the sun and the moon, so the moon's entire face is illuminated as seen from Earth. This happens about once every 29.5 days — the length of a full lunar cycle, also called a synodic month. Because a full moon is essentially opposite the sun in the sky, it rises right around the time the sun sets and sets right around the time the sun rises, making it visible all night long. Most months only have one full moon, though occasionally a second one falls within the same calendar month — commonly nicknamed a "blue moon."

Why moonrise and sunset rarely line up exactly

Even though a full moon is roughly opposite the sun, "roughly" is the key word. The moon's orbit is tilted about five degrees relative to Earth's orbit around the sun, and its orbit isn't a perfect circle — both factors shift the precise moment of moonrise earlier or later relative to sunset by anywhere from a few minutes to over an hour, depending on the date and your location's latitude. That's what makes a true simultaneous moonrise-and-sunset a special, fairly rare event worth planning for, rather than something that happens every full moon.

Types of sunrise and sunset

Astronomers actually define several distinct moments around sunrise and sunset, based on how far the sun sits below the horizon:

• Sunrise / Sunset (0°): The moment the sun's upper edge first appears above the horizon in the morning, or its lower edge touches the horizon in the evening. This is the everyday definition most people mean by "sunset" — and the moment this tool uses for its calculations.
• Civil twilight (-6°): The sun is just below the horizon. There's still enough natural light for most outdoor activities without artificial lighting, and the brightest stars and planets may start to appear.
• Nautical twilight (-12°): The horizon is still faintly visible at sea, historically letting sailors navigate by the stars while still seeing the horizon line.
• Astronomical twilight (-18°): The sky is fully dark for practical purposes; the last traces of scattered sunlight disappear, and faint deep-sky objects become visible to astronomers.

Moonrise and moonset follow the same horizon-crossing logic as sunrise and sunset, just applied to the moon instead of the sun — which is exactly what makes it possible to calculate the rare moments when both line up.