The Earth - getting bigger or smaller?

This article from the BBC compares the ways in which the Earth is gaining and losing mass. It makes excellent discussion material for sixth form Physics students since it involves gravity, astronomy, mass-energy conversion and climate change all in one discussion!

"Using some back-of-the-envelope-style calculations, Dr Smith, with help from physicist and Cambridge University colleague Dave Ansell, drew up a balance sheet of what's coming in, and what's going out. All figures are estimated.

By far the biggest contributor to the world's mass is the 40,000 tonnes of dust that is falling from space to Earth, says Dr Smith."