How many billions of years ago do cosmologists estimate that our solar system began?

Cosmologists estimate that our solar system formed about 4.5 billion years ago based on various lines of evidence, including the ages of the oldest meteorites and the study of planetary formation in the context of the Milky Way galaxy. The formation of the solar system is believed to have begun with the collapse of a region within a large molecular cloud, leading to the formation of the Sun and the surrounding protoplanetary disk from which the planets emerged.

This time frame is supported by the dating of the oldest minerals found on Earth and the Moon, as well as samples taken from meteorites that provide insight into the conditions and time scales of the early solar system. Understanding that the age of the solar system significantly exceeds both 4.5 million and 45 million years is crucial, as these time frames are far too short for the formation processes we observe in the cosmos. Similarly, the notion of 45 billion years is also not consistent with the current scientific understanding of the age of the universe, which is estimated to be about 13.8 billion years. The 4.5 billion-year estimate is thus a key benchmark in our comprehension of solar system history and evolution.