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Gravitational Collapse Links Observations of the interstellar medium, together with calculations of stellar models have led astrophysicists to assemble a theory of how stars are born and why they shine. The theory of stellar genesis has been successful in explaining how stars are formed in vast clouds of interstellar gas and dust. Thanks to modern space-borne instruments like the Hubble Telescope we can look into these nurseries and observe the process of starbirth to see how it contributes to the making of a star. Interstellar gas was discovered at the beginning of the 20th Century, by a German astronomer, Johannes F.Hartmann. Hartmann noticed that the spectra of certain binary stars exhibited two absorption lines whose wavelengths did not change despite the periodic variation of all their other spectral lines.