You would think that with the increase in population and the billions of tons of construction resulting from human activities, planet Earth will see its mass increase over time. In reality, it is the opposite: the Earth is losing weight! Here’s why.
The Earth weighs approximately 5,970 quadrillons of kg, or 624 kg. A mass calculated from the universal gravitation and the rotation speed satellites in orbit. This mass is almost constant. One might think that it keeps increasing. According to a study by the University of Leicester, “ technosphere “(Houses, factories, farms, mines, roads, computer systems …) of human activities thus represents 30,000 billion tonnes, or about 50 kg per square meter of the earth’s surface. The biomass human is estimated at 60 million tonnes and the total biomass (plants, bacteria, animals …) to 550 billion tonnes. But all this does not add up to the total mass of the Earth: both humans and objects are made from matter already present on Earth in another form.
Weight loss for the Earth: 97,607 tons per year
Conversely, the Earth loses a tiny bit of its mass. At the top of theatmosphere, the gravity is so small that it fails to retain the atoms the lightest, thehydrogen and thehelium. What’s more, the air is so thin at this altitude (about 500 km) that the molecules hardly suffer any more collisions. Without any obstacle in their path, nothing prevents those with sufficient speed from escaping into space: 95,000 tonnes of hydrogen and 1,600 tonnes of helium thus flee towards the cosmos every year. The Earth also loses some weight by radioactivity. The radioactive elements contained in rocks and the core disintegrate and escape by radiation to space (around 7 tonnes / year). Finally, the satellites and the rockets launched from Earth, made from terrestrial materials, lighten the Planet a little when they are not in orbit (approximately -1,000 tonnes / year).
Weight gain for the Earth: 16,160 tons per year
The Earth is still gaining a little weight. 84,000 meteorites fall to Earth every year, but most only weigh a few grams. This represents 16,000 tonnes of additional mass per year. Due to the global warming, the Earth also gains 160 tons per year, thanks to the effect of thermodynamics : the atmosphere rreceives more energy than it loses, which slightly increases its mass.
Global balance: -81,447 tonnes per year
In total, the Earth loses 97,607 tonnes of material per year and gains 16,160 tonnes. The Earth is thus each year lighter by 81,447 tons per year or 0,000,000,000,000,014% of its weight. Suffice to say that we do not see the difference.
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