what keeps the earth's atmosphere from floating away
Atmospheric escape Earth's magnetic field protects it from solar winds and prevents escape of ions, except near the magnetic poles where charged particles stream towards the earth along magnetic field lines. The gravitational attraction of Earth's mass prevents other non-thermal loss processes from appreciably depleting the atmosphere.[specify] Yet Earth's atmosphere is two orders of magnitude less dense than that of Venus at the surface. Because of the temperature regime of Earth, CO2 and H2O are sequestered in the hydrosphere and lithosphere. H2O vapor is sequestered as liquid H2O in oceans, greatly decreasing the atmospheric density. With liquid water running over the surface of Earth, CO2 can be drawn down from the atmosphere and sequestered in sedimentary rocks. Some estimates indicate that nearly all carbon on Earth is contained in sedimentary rocks, with the atmospheric portion being approximately 1/250,000 of Earth's CO2 reservoir.[citation needed] If both of the reservoirs were released to the atmosphere, Earth's atmosphere would be even denser than Venus's atmosphere. Therefore, the dominant “loss” mechanism of Earth's atmosphere is not escape to space, but sequestration.[citation needed] However, in 1 billion years' time, the Sun will be 10% brighter than it is now, making it hot enough for Earth to lose enough hydrogen to space to cause it to lose all of its water (See Future of Earth#Loss of oceans).