The GPP studied the Earth's thermosphere, ionosphere and mesosphere energetics and dynamics using broadband spectroscopy. Above there is an intermediate layer of mesosphere which separates the troposphere from the thermosphere. Above the troposphere, the atmosphere is usually divided into the stratosphere, mesosphere, and thermosphere. They both have a troposphere, stratosphere, mesosphere, and thermosphere. Variability in irradiance influences conditions in the ionosphere and thermosphere. It incorporates all of the troposphere, stratosphere, mesosphere, and the lower part of the thermosphere. From lowest to highest, the atmospheric layers are the troposphere, stratosphere, thermosphere and exosphere. The thermosphere gradually transitions to the exosphere. The ionosphere almost coincides with the thermosphere. These particles, mainly electrons and protons, precipitate into the upper atmosphere (thermosphere/exosphere). The lower part of the thermosphere, from above Earth's surface, contains the ionosphere. ICON will perform a two-year mission to observe conditions in both the thermosphere and ionosphere. Weather does not occur in the higher stratosphere or thermosphere. The reaction of the thermosphere to a large magnetospheric storm is called thermospheric storm. The International Space Station orbits the Earth within the middle of the thermosphere, between .