Outer Space

I am going to talk a little about outer space and the atmosphere today. According to Wikipedia "outer Space  is the void that exists between celestial bodies, including the Earth.^[1] It is not completely empty, but consists of a hard vacuum containing a low density of particles, predominantly a plasma of hydrogen and helium as well aselectromagnetic radiation, magnetic fields, neutrinos, dust and cosmic rays. The baseline temperature, as set by the background radiation from the Big Bang, is 2.7 kelvin (K). Plasma with a number density of less than one hydrogen atom per cubic metre and a temperature of millions of kelvin in the space between galaxies accounts for most of the baryonic (ordinary) matter in outer space; local concentrations have condensed into stars and galaxies. In most galaxies, observations provide evidence that 90% of the mass is in an unknown form, called dark matter, which interacts with other matter through gravitational but not electromagnetic forces." The atmosphere is a layer of gases surrounding a planet or other material body of sufficient mass that is held in place by the gravity of the body. An atmosphere is more likely to be retained if the gravity is high and the atmosphere's temperature is low. According to Wikipedia "The Earth's atmosphere consists, from the ground up, of the troposphere (which includes the planetary boundary layer or peplosphere as lowest layer), stratosphere (which includes the ozone layer, mesosphere, thermosphere (which contains the ionosphere), exosphere and also the magnetosphere. Each of the layers has a different lapse rate, defining the rate of change in temperature with height.Three quarters of the atmospheric mass resides within the troposphere, and the depth of this layer varies between 17 km at the equator and 7 km at the poles. The ozone layer, which absorbs ultraviolet energy from the Sun, is located primarily in the stratosphere, at altitudes of 15 to 35 km. The Kármán line, located within the thermosphere at an altitude of 100 km, is commonly used to define the boundary between the Earth's atmosphere and outer space. However, the exosphere can extend from 500 up to 1,000 km above the surface, where it interacts with the planet's magnetosphere."