Scientists first make observations that raise a particular question. In order to explain the observed phenomenon, they develop a number of possible explanations, or hypotheses. This is the inductive part of science, observing and constructing plausible arguments for why an event occurred.
As indicated earlier, the Bible does not fix the age of the earth, contrary to the claims of Answers in Genesis. Historically, their claim comes from the work of James Ussher, Bishop in the Church of Ireland, from 1625 to 1656.
The oldest Earth rocks are about 3.8 billion years old, although some small, very old grains found in sandstone have been dated at 4.1 billion years. The solar system is believed to be about 4.6 billion years old. Therefore, there is little evidence left on Earth about the very early solar system.