Episode description

Scales don’t come planet-sized, so answering a question from David in Ghana may require some ingenuity, after all, calculating the weight of the Earth is a huge task. Using a set of weighing scales and a 400 year-old equation, Marnie Chesterton attempts to find out just how much the Earth weighs and is it getting heavier or lighter over time? But how would a planet gain or lose mass? Which tips the scales: meteorites falling from space or gases constantly escaping from our atmosphere? And does the answer have any implications for the future of Earth? Could the atmosphere eventually run out? Contributors: Anuradha TK, former project director at ISRO Matt Genge, geologist at Imperial College London Jon Larsen, researcher at the University of Oslo Anjali Tripathi, astrophysicist Ethan Seigel, journalist and astrophysicist

Presented by Marnie Chesterton. Produced by Caroline Steel for the BBC World Service.

[Image: Earth on scales. Credit: Getty Images]