Zero Gravity Day (Mujūryoku no Hi)

What is Zero Gravity Day?

June 16th is "Zero Gravity Day" every year. It comes from the wordplay "mu (6) - jū (10) - ryoku (6)" — a phonetic match for "mujūryoku," meaning "zero gravity" or "weightlessness." The anniversary was established by the Japan Microgravity Center (JAMIC), a former zero-gravity research facility located in Kamisunagawa, Hokkaido. Its goal is to spread awareness of the possibilities that weightless (microgravity) environments — like those found in space — offer for scientific research and industry, and to nurture curiosity about uncharted frontiers.

Historical facts left behind by one of the world's largest experimental facilities

Japan was once home to a world-class hub for microgravity experiments.

• Scientific ingenuity built on a former coal mine: As a matter of fact, the facility opened in 1991 by repurposing the vertical shaft (about 700 meters deep) of the closed Mitsui Sunagawa coal mine. Using a "free-fall" method that took advantage of this depth, it was able to generate about 10 seconds of high-quality weightlessness while remaining on the ground — a remarkable historical achievement.
• A foundation for space development: As a matter of fact, JAMIC was used to prepare experiments for the International Space Station (ISS), as well as for synthesizing new materials and conducting combustion experiments. Until its closure in 2003, it scientifically and physically supported Japan's space science and technology.

Scientific facts about microgravity

In an environment freed from gravity, phenomena occur that defy the common sense of life on Earth.

• The disappearance of "convection" and uniform crystals: On Earth, warm things rise and cool things sink, creating "convection." In fact, without convection in a weightless environment, substances mix uniformly, making it scientifically possible to grow protein crystals and new materials of a purity and size impossible on Earth.
• Flames become "spherical": Flames on Earth are stretched upward by convection-driven updrafts. However, in fact, combustion in microgravity receives oxygen evenly from all directions, so the flame forms a beautiful blue "sphere." This is essential data for the scientific understanding of combustion efficiency.

Interesting facts about weightlessness

• Not "zero G" but "micro-G": As a matter of fact, complete weightlessness is a theoretical concept — even inside experimental facilities or the ISS, slight gravity or vibration remains, which is why scientists refer to it as "microgravity."
• The "height increase" phenomenon in zero gravity: As a matter of fact, when astronauts go to space, the cartilage between their vertebrae expands once freed from gravity, making them several centimeters taller. This vividly demonstrates gravity's scientific influence on the skeleton.
• A world ruled by "surface tension": Without gravity, liquids try to form perfect spheres due to their own surface tension. In fact, water floating in midair and forming large spherical blobs is a visualization of physical force balance.
• Three ways to create "weightlessness": As a matter of fact, the three main scientifically usable methods are "drop towers" like JAMIC, "parabolic flights" where an aircraft dives steeply, and "satellites" like the ISS that continuously free-fall around the Earth.
• The scientific mechanism of space sickness: When gravity disappears, signals from the inner ear's semicircular canals and otolith organs conflict with information from the eyes. As a matter of fact, this confusion in the brain is the explained cause of "space sickness."

Ideas for spending Zero Gravity Day

• To mark "June 16th, Zero Gravity Day," try freeing your mind from "gravity" — that is, pressure. Let go of the responsibilities and stresses of the new fiscal year, the "gravity of the mind," for a moment, and practice the intellectual mindfulness of unrestricted, free thinking.
• Watch a space documentary or sci-fi film. Imagining a world without the "normal" pull of gravity stimulates the temporal lobe and serves as scientific training to refresh your creative thinking.
• Enjoy the sensation of "floating" in the bath. Buoyancy in water, as a matter of fact, creates a pseudo-weightless state. This frees your muscles and joints from gravity and produces a scientifically recognized relaxation effect (floating therapy) shown by brainwave changes.
• Check out the latest news on the space industry and "space tourism." Confirm the scientific and social progress through which JAMIC's once-dreamed-of "accessible space" is, in fact, becoming a reality.

When the invisible gravity that binds you gently vanishes, your mind is set free into infinite space, gaining the flexible wings to draw out a new version of yourself

June 16th is a day to step outside the familiar framework of "gravity" and look at the world anew. Day after day, we tend to look down, pulled by the gravity of social rules and others' expectations. But just as scientists once pursued weightlessness deep underground in Hokkaido, we too can choose, of our own will, to set down our burdens and experience a moment of weightless flight. Aren't your shoulders carrying too much weight in this new fiscal year? Today, take a deep breath and bring your inner gravity to zero. In a lighter mind, new ideas and hopes will begin to take shape — pure and round, like the spherical flame of a weightless fire. Carry that lightness forward, and let your days from here on become freer and more vivid.