Several radio telescopes observe the object simultaneously, and a computer analyzes how the signals interfere with each other. The matter between stars, composed of two components, gas and dust, intermixed throughout all of space. The law that a field follows if its strength decreases with the square of the distance. Fields that follow the inverse square law rapidly decrease in strength as the distance increases, but never quite reach zero. A galaxy which does not fit into any of the other major categories in the Hubble clasification scheme.
Most elements can exist in several isotopic forms.
A common example of an isotope is deuterium, which differs from normal hydrogen by the presence of an extra neutron in the nucleus.