NEW DELHI: In a cosmic balancing act, scientists have revealed that Earth is slowly losing weight, shedding up to 60,000 tonnes of mass each year. However, this planetary weight loss is so minuscule compared to Earth’s total mass that it has virtually no impact on our world.
The primary reason for this decline is “atmospheric escape,” where tens of thousands of tonnes of light gases, primarily hydrogen and helium, leak from the upper atmosphere into space annually. In the upper atmosphere, some gas molecules, accelerated by energy from the sun, reach speeds exceeding Earth’s escape velocity of 11 kilometers per second, allowing them to break free from our planet’s gravitational pull.
Hydrogen is often created when ultraviolet light breaks apart water molecules, while helium is constantly produced by the radioactive decay of elements deep within the Earth.
This loss is partially counteracted by a steady influx of cosmic material. Earth gains approximately 41,000 to 50,000 tonnes of mass each year, mostly in the form of meteorites and space dust that are captured by its gravity. When the gains and losses are tallied, the net result is an annual loss of up to 60,000 tonnes.
While this figure sounds enormous, it’s a drop in the ocean for a planet with a mass of nearly six sextillion tonnes. The annual loss is equivalent to the mass of about 360 people—a number surpassed by global population growth in under three minutes. Over the 4.5 billion years since Earth formed, this process has only reduced its total mass by about four parts per billion.
Human activity also contributes a tiny fraction to this weight loss. About 65 tonnes of mass are lost each year from spacecraft sent on missions from which they never return. Orbiting satellites, however, do not count towards this loss as they eventually fall back to Earth.
