These other effects are very large and dominate the effects of changing mass, which, as we will see, is very small indeed. Thus we must resort to individually accounting for each effect changing the Earth's mass. First, consider the meteorite addition of mass to the Earth. Most planetary scientists agree that the Earth gains mass at a rate of about 50 million kilograms per year due to meteorites. Compare this with the size of visible meteors, such as the Leonids, which are more like a few mm across.
Astronomers make total meteorite-mass measurements in a variety of ways.
The best way is to study the surfaces of man-made satellites which are returned to Earth. These satellites are pock-marked by meteorite impacts, and by studying the shape and size of these craters, and because we know exactly how long the satellite was exposed to space, we can directly calculate how much mass struck that surface, and then extend those findings to the Earth itself. Other scientists measure the amounts of radioactive elements such as Osmium in the ocean floors. Thus, any radioactive Osmium must have been recently added from space, allowing scientists to estimate total added mass. The second effect changing the mass of the Earth is loss of helium gas from the atmosphere.