عنوان مقاله [English]
نویسنده [English]چکیده [English]
How old is the solar system?
One thing is certain about the age of the solar system – it cannot be greater than the age of the Universe, whose expansion from a flash of light began about 12 to 18 billion years ago. We shall start our story from the childhood of the Universe.
At first, the Universe was pure energy; there was no solid matter. Quickly this energy condensed to make energetic particles which, in turn, formed into electrons and the nuclei of hydrogen and helium. As the young universe expanded and became rarified, it also cooled. The gas became clumpy and formed into swirling concentrations that gradually separated into isolated eddies that comprised primordial galaxies. Within these galaxies, smaller concentrations appeared, and these in turn fragmented, giving birth to clusters of stars.