Now Yelnya is emptying out. It’s doing so below the duvet of cloud, out of sight of regular optical satellite tv for pc imagery. However as The Economist defined in a current Know-how Quarterly, synthetic-aperture radar (SAR) satellites assist to get round this downside. The European Area Company’s Sentinel-1 SAR satellites make photographs of each spot in Europe each six days. The outcomes are grainy, which means particular person autos or buildings can’t be picked out. However man-made buildings mirror radar waves from SAR satellites notably effectively. Right here, they’ve been colored purple. That enables us to see the dramatic change at Yelnya between January twenty third and February eleventh.