In a recent experiment, conducted by BBC Radio 4, two scientists, Chris Smith and Dave Angel, have found out that the earth is actually getting lighter with every passing year. This is despite the fact that the earth sucks in about 40,000 tonnes of space dust every year. The earth’s gravity pulls these particles into the atmosphere and they stay there and become a part of the earth’s mass.
The current mass of the earth is about 5,972,000,000,000,000,000,000 (Five thousand nine hundred and seventy two quintillions) tonnes. Scientists have found that it is losing about 50,000 tonnes of mass a year, which is about 0.000000000000001% of the total mass of the planet. So, what exactly is causing that loss of mass despite the additional 40,000 tonnes of space dust every year?
The answer to that question is Hydrogen and Helium. These two gases, which are the lightest gases on the Periodic table, escape the earth’s gravity and get lost in space. The escaped hydrogen account for around 95,000 tonnes of mass and the helium accounts for about 1600 tonnes. These gases are so light that even gravity fails to act on them after a certain point and they escape.
There is another factor that accounts for a minor loss of mass- the loss of the planet’s energy. Every planet requires energy to operate. The earth burns out energy which amounts to around 16 tonnes every year. Although, compared to the overall weight of the earth, it is almost negligible.
Every other loss or gain of weight is always balanced out in the long run.
For example, spacecrafts leaving the earth will eventually fall back into the earth again. Anything that is built is built with the elements present in the earth itself. They just change shape and hence, there is no net addition or loss of mass.