Gravity is the universal attraction between any two objects with mass. It is directly proportional to the product of the masses and inversely proportional to the square of the distance separating them. This means gravitational pull increases with mass but rapidly diminishes as the distance grows. To find the least gravitational pull, one must seek environments that either minimize the attracting mass or maximize the distance from any significant concentration of mass. These locations range from subtle variations on Earth to the vast expanses of the cosmos.
Local Gravity Anomalies on Earth
Even on Earth, the gravitational field is not perfectly uniform, exhibiting measurable local variations called gravity anomalies. These differences are caused by deviations from a perfectly smooth, uniform planet model. One factor is the Earth’s rotation, which produces a centrifugal force that slightly counteracts gravity. This effect is most pronounced at the equator, making gravity measurably weaker there compared to the poles.
Altitude also plays a role because gravity decreases with distance from the planet’s center of mass. Standing atop a high mountain, such as Mount Everest, results in a slightly weaker pull than standing at sea level. This is due to the increased distance from the bulk of the Earth’s mass. For instance, an increase in altitude from sea level to 9,000 meters causes a weight decrease of approximately 0.29%.
The density of the Earth’s crust also varies significantly, creating localized “gravity holes” or “gravity highs.” Areas with thick, low-density materials, such as the roots of mountain ranges or large basins filled with sedimentary rock, show a weaker gravitational pull. Conversely, a dense metallic ore deposit beneath the surface creates a positive anomaly, resulting in a slightly stronger pull in that specific location.
Surface Gravity on Small Celestial Bodies
The most straightforward way to find a sustained, extremely low gravitational pull is to stand on the surface of a celestial body with very little mass. The surface gravity of an object is directly tied to its mass, meaning that small asteroids and comets have a negligible pull compared to a planet. These tiny worlds often lack enough mass to form a spherical shape, which is a visual cue to their feeble gravity.
A prime example is the near-Earth asteroid 25143 Itokawa, a small, peanut-shaped “rubble pile.” It measures approximately 535 by 294 by 209 meters. The Japanese Hayabusa probe found that the asteroid’s surface gravity is roughly 1/100,000th that of Earth’s. An object weighing 70 kilograms on Earth would weigh a mere 0.7 grams on Itokawa.
The gravitational field is so weak that the Hayabusa spacecraft could not orbit the asteroid and instead had to “park” nearby, using thrusters to maintain position. The escape velocity, the speed needed to leave the object’s surface permanently, is estimated to be only 0.2 meters per second. A person could easily jump off the asteroid entirely and float away into space. This environment represents a substantial minimization of gravity based purely on the small mass of the body.
The Emptiness of Deep Space and Equilibrium Points
Moving away from the surface of any object, the lowest gravitational environment is achieved by maximizing distance from all significant masses. In the vast reaches of intergalactic space, far from any star system or major galaxy, the gravitational pull from any single body becomes negligible. While the pull is never truly zero, the immense distances ensure that the influence of the nearest stars and galaxies is diluted to an almost immeasurable force.
A unique microgravity environment exists in specific, calculated positions called Lagrange Points. Here, the gravitational pulls of two large orbiting bodies balance with the centripetal force of the system. These are points of gravitational equilibrium where a small object can maintain a fixed position relative to the two larger masses with minimal effort. There are five such points in any two-body system, such as the Sun and Earth.
The Sun-Earth system’s L1 and L2 points, located approximately 1.5 million kilometers from Earth, are often used as “parking spots” for spacecraft. The James Webb Space Telescope, for example, is positioned at L2. At these locations, the combined pull of the Sun and Earth, along with the required centripetal force, creates a balanced state where an object essentially stays put. These equilibrium points offer a stable, low-force environment where the influence of the two largest masses effectively cancels out.