<P> Outer space , or just space , is the expanse that exists between celestial bodies , including Earth . Outer space 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 as electromagnetic radiation , magnetic fields , neutrinos , dust , and cosmic rays . The baseline temperature , as set by the background radiation from the Big Bang , is 2.7 kelvins ( K ) ( − 270.45 ° C ; − 454.81 ° F ) . Plasma with a number density of less than one hydrogen atom per cubic metre and a temperature of millions of kelvins in the space between galaxies accounts for most of the baryonic ( ordinary ) matter in outer space ; local concentrations have condensed into stars and galaxies . Observations indicate that 90 % of the mass in most galaxies is in an unknown form , called dark matter , which interacts with other matter through gravitational but not electromagnetic forces . Other observations indicate that the majority of the mass - energy in the observable universe is a poorly understood vacuum energy of space which astronomers label dark energy . Intergalactic space takes up most of the volume of the Universe , but even galaxies and star systems consist almost entirely of empty space . </P>
<P> Outer space , or just space , is the expanse that exists between celestial bodies , including Earth . Outer space 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 as electromagnetic radiation , magnetic fields , neutrinos , dust , and cosmic rays . The baseline temperature , as set by the background radiation from the Big Bang , is 2.7 kelvins ( K ) ( − 270.45 ° C ; − 454.81 ° F ) . Plasma with a number density of less than one hydrogen atom per cubic metre and a temperature of millions of kelvins in the space between galaxies accounts for most of the baryonic ( ordinary ) matter in outer space ; local concentrations have condensed into stars and galaxies . Observations indicate that 90 % of the mass in most galaxies is in an unknown form , called dark matter , which interacts with other matter through gravitational but not electromagnetic forces . Other observations indicate that the majority of the mass - energy in the observable universe is a poorly understood vacuum energy of space which astronomers label dark energy . Intergalactic space takes up most of the volume of the Universe , but even galaxies and star systems consist almost entirely of empty space . </P>
which layer takes up most of the earth 's volume
which layer takes up most of the earth 's volume
space
space