Earth’s atmosphere was known to “breathe” in a cycle lasting nearly a month. Now scientists say the planet takes a quick breath every few days. The breathing-like activity is the result of high-speed solar wind disturbances that cause a recurrent expansion and contraction of Earth’s atmosphere every few days satellite observations show. This atmospheric mode could affect radio communication orbiting satellites and possibly the Earth s climate researchers say. The expansion and contraction happens way up in the Earth s thermosphere the layer of the atmosphere that extends from about 60 to 300 miles 96.5 to 483 kilometers above the planet s surface. The thermosphere is constantly interacting with the sun s upper atmosphere as it expands out into the solar system said one of the researchers who made the discovery Jeff Thayer of the University of Colorado in Boulder during a press conference at the annual meeting of the American Geophysical Union in San Francisco yesterday. This interaction causes an energy exchange that can change the density of the thermosphere how closely the gas molecules within it are packed together . As its density changes the thermosphere expands and contracts. 5 7 and 9 Extreme ultraviolet UV radiation from the sun was known to cause a 27-day expansion-and-contraction cycle by changing the thermosphere s density through heating. Thayer and his team analyzed data from the German Challenging Minisatellite Payload CHAMP and the NASA Advanced composition Explorer satellite and found that the thermosphere also appeared to breathe every five seven and nine days “which was unexpected ” Thayer said. The researchers determined that the cause of these shorter expansions and contractions was high-speed winds generated by relatively cool pockets on the sun s surface known as solar coronal holes which periodically rotate around the solar surface. Thayer said this finding could help improve satellite tracking which was part of the aim of the study which was funded in part by the U.S. Air Force. The thermosphere is heavily populated with spacecraft including the International Space Station and more than 800 operational satellites.