The Milky Way

The Milky Way in numbers

Disk diameter

~105,000 light-years

Thin disk thickness

~1,000 light-years

Estimated stars

100–400 billion

Mass (with dark halo)

~1.5 trillion solar masses

Sun's distance from centre

26,670 light-years

Sun's orbital period

~230 million years

Age

~13.6 billion years

Classification

Barred spiral (SBbc)

This model illustrates shape and scale; it is not a dynamical simulation. Stars are scattered along logarithmic spirals with random noise, and the true positions of the spiral arms are still being remeasured — the map of the galaxy has been redrawn several times in the past two decades. The figures in the table come from observation.