The universe began 13.8 billion years age with the Big Bang. The Big Bang is a theory about how the universe started and the formation of stars and galaxies. The universe was very hot, small and dense with no stars, atoms, form, or structure called a singularity. then inflated over the next 13.8 billion years to the cosmos that we know today.
The universe is 13.8 billion years old. Astronomers estimate the age of the universe by looking for the oldest stars; and by measuring the rate of expansion. The universe cannot be younger than the objects contained inside of it. By determining the ages of the oldest stars, scientists are able to put a limit on the age.
The Solar System is the gravitationally bound system of the Sun and the objects that orbit it, either directly or indirectly. Of the objects that orbit the Sun directly, the largest are the eight planets, with the remainder being smaller objects, the dwarf planets and small Solar System bodies.