High Quality Content by WIKIPEDIA articles! This more than twenty billion years timeline of our universe shows the best estimates of the occurrence of events since its beginning, up until anticipated events in the near future. Zero of the scale is the present day. A large step on the scale is one billion years, a small step one hundred million years. The past time have a minus sign, e.g. the oldest rock on Earth was formed about four billion years ago and this is marked at -4e+09 years. The "Big Bang" event happened 13.7 billion years ago, see age of the Universe.