6.1 Describe the contributions of Edwin Hubble to our understanding of galaxies and the
expanding universe.
Hubble developed a new system for the classifying galaxies , which ordered according to
their content , distance , shape and brightness. In its observations found that the emission
of light from the galaxies have a redshift and moved away from each other at a constant
speed. From these observations, in 1929 he formulated Hubble’s Law, which could
determine the approximate age of the universe, and also prove that the universe was
expanding steadily.
In Hubble’s Law Theory, the Big Bang is also stated as if the universe is constantly
expanding since its inception, there had to be a moment in history in which that expansion
began , which is now known as the Big Bang.
6.2 When did the Big Bang Occur?
What observational evidence do we have that supports this conclusion?The Big Bang is
estimated to have happened 13.8 billion years ago. There are three evidences that are
considered the empirical evidences supporting the Big Bang theory. These are: the
expansion of the universe is expressed in Hubble’s Law and can be seen in the redshifts of
galaxies, the detailed measurements of the cosmic microwave background, and the
abundance of light elements. Also, the correlation function of large scale structure of the
Universe fits the theory of the Big Bang.
6.3 When did the Milky Way galaxy form, or at least begin to form? How do our
