Atmosphere of Earth (see the temperature section, below). Because the general pattern of the temperature/altitude profile is constant and measurable by means of instrumented balloon soundings, the temperature behavior provides a useful metric to distinguish atmospheric layers. In this way, Earth's atmosphere can be divided (called atmospheric stratification) into five main layers. Excluding the exosphere, the atmosphere has four primary layers, which are the troposphere, stratosphere, mesosphere, and thermosphere. From highest to lowest, the five main layers are: The exosphere is the outermost layer of Earth's atmosphere (i.e. the upper limit of the atmosphere). It extends from the exobase, which is located at
Mass concentration (astronomy) Schiesser of the NASA Manned Spacecraft Center in Houston then worked out the "fix" that was first applied to Apollo 12 and permitted its landing within 535 feet of the target, the previously-landed Surveyor 3 spacecraft. In May 2013 a NASA study was published with results from the twin GRAIL probes, that mapped mass concentrations on Earth's Moon. Mass concentration (astronomy) In astronomy and astrophysics, a mass concentration (or mascon) is a region of a planet or moon's crust that contains a large positive gravitational anomaly. In general, the word "mascon" can be used as a noun to refer to