The BBC’s Jonathan Amos looks at the ways satellites have collected imagery and data on the Hunga-Tonga Hunga-Ha’apai¹ volcanic eruption.

1. The two islands of Hunga-Tonga and Hunga-Ha’apai were joined by a volcanic eruption in 2009. They’re basically two exposed parts of a much larger underwater volcanic caldera. As Alastair Bonnett notes in Elsewhere, the new island hasn’t—hadn’t—been renamed yet.