The Milky Way

The Milky Way Galaxy
The Milky Way system is a spiral galaxy consisting of over 400 billion stars , plus gas and dust.
Milky Way is actually a giant, as its mass is probably between 750 billion and one trillion solar masses, and its diameter is about 100,000 light years.
The main disk of the Milky Way Galaxy is about 80,000 to 100,000 light-years in diameter, about 250,000 to 300,000 light-years in circumference, and outside the Galactic core, about 1,000 light-years in thickness.
It is composed of 200 billion stars but this number might reach 400 billion if small-mass stars predominate.
It is extremely difficult to define the age at which the Milky Way formed, but the age of the oldest stars in the Galaxy is currently estimated to be about 13.6 billion years, which is nearly as old as the Universe itself.