Earth is, on balance, gaining mass.
While it might seem counterintuitive, given processes like rocket launches and the constant escape of gases into space, the Earth actually accumulates more mass than it loses. This gain primarily comes from space dust and meteorites.
Mass Gain: Cosmic Dust and Meteorites
The Earth sweeps up a significant amount of interplanetary dust and small meteorites as it orbits the sun. Estimates vary, but a commonly cited figure is around 40,000 metric tons per year. These particles are remnants from the formation of the solar system and debris from asteroids and comets.
Mass Loss: Atmospheric Escape
The Earth's atmosphere is constantly leaking gases, primarily hydrogen and helium, into space. This happens because these lighter elements can reach escape velocity in the upper atmosphere due to solar radiation and other factors. However, the amount of mass lost through atmospheric escape is significantly less than the mass gained from cosmic dust and meteorites.
A Net Gain
Despite the ongoing loss of atmospheric gases, the influx of space dust and meteorites outweighs it. Therefore, the Earth experiences a net gain in mass each year. While this gain is relatively small compared to the Earth's total mass, it is still a measurable phenomenon.
| Process | Mass Gain/Loss (approximate) |
|---|---|
| Cosmic Dust/Meteorites | +40,000 tons/year |
| Atmospheric Escape | - Much less than gain |
Therefore, the Earth is constantly increasing its mass due to the accretion of interplanetary material, even if it's a tiny amount relative to the Earth's total mass.
