satellites are frequently used to make observations of the orbit on earth
all matter is made up of atoms
in any element all atoms are the same
elements in a compound are always in a constant ratio: apex
this age may represent the age of the earth's accretion, of core formation, or of the material from which the earth formed. this dating is based on evidence from radiometric age-dating of meteorite material and is consistent with the radiometric ages of the oldest-known terrestrial and lunar samples.