Landslide caused global seismic mystery  Seismologists have solved the mystery of what caused a weird ‘ringing bell’ signal that shook the world for nine days last September.  The signal, recorded by seismic stations worldwide, came from the collapse of a mountain top in Greenland, which produced a huge landslide and ice avalanche into a fjord.  The impact of the debris caused a back-and-forth sloshing of waves between mountainsides, which lasted for more than a week.  “It’s the first time we’ve found a seismic signal of this type in the global record: some people thought their sensors were broken,” says geologist and co-author Kristian Svennevig.  Bacteria adapt to winter daylight  As winter approaches, some communities of bacteria seem to respond to shorter days and lower light intensity, even though individual bacteria live only for a few hours.   In the lab, cyanobacteria exposed to short, winter-like periods of daylight adjusted their membrane lipids and gene expression to prepare themselves for colder temperatures.  Exposure to longer daylight activated genes involved in protecting the bacteria from heat and light stress caused by the Sun.  This adaptation to summer daylight might help to explain the timing of seasonal blooms of cyanobacteria that swamp waterways in warmer seasons.  Satellites outshine stars, warn astronomers  Five extremely reflective prototype satellites will be launched into space this week, forming part of a system that aims to provide a space-based mobile phone network.  The BlueWalker 3 satellites from AST SpaceMobile are so bright they might hinder astronomers’ work and our ability to spot asteroids hurtling towards us.  “I fear that we’re at risk of losing the sky,” says astrophysicist Grant Tremblay.  Aircraft detect microbes 3 kilometres up  Fungi and bacteria have been collected by aircraft flying above Japan at altitudes between 1,000 and 3,000 metres.  Researchers identified 266 fungal and 305 bacterial species, many of which they were able to grow in the lab.  The scientists estimate that the spores had travelled thousands of kilometres, thanks to strong winds from central Asia.  The bacteria and fungi include human pathogens, but it’s not known if they could trigger disease when they fall back to Earth.  Forests are more than trees  In his new book Treewilding, microbial ecologist Jake Robinson questions whether just planting trees is the solution to deforestation.  He speaks to Forrest Fleischman, a scholar of forest and environmental policy, who “proposes that people should not just plant trees but ‘grow’ them,” writes biologist and writer Debraj Manna in his review of the book.  “This means knowing what species suit an area and how they are connected to the lives of the local people and wildlife.”  For these, and other wildlife, nature, and environmental news items, go to www.nature.com/nature/