AuroracastUKLearn
The Milky Way
Our own galaxy, seen from the inside and edge on.
Seeing it from the UK
This is the one thing on this page that a dark sky decides for you. From a town you will see nothing at all, no matter how clear the night. From genuinely dark countryside with no moon it is obvious, a soft uneven band running up from the southern horizon and overhead. Late August through September, once it is properly dark, is the best of it from here. Your eyes are the right instrument, given twenty minutes to adapt, and binoculars will break the brighter patches into star clouds. A telescope is the wrong tool: it magnifies far too much to show a band that crosses the whole sky.
Every star you can see with your eyes belongs to the Milky Way, and so do you. It is a barred spiral galaxy, a flattened disc of a few hundred billion stars turning slowly around a heavy centre, and the Sun sits about two thirds of the way out in one of the spiral arms.
The band across the sky is that same disc seen edge on. Looking along the plane of the galaxy puts far more stars in the line of sight than looking out of it, and at this distance they blur into a single soft glow. The dark rifts running through it are not gaps. They are clouds of dust in the arms nearer to us, blocking the light of everything behind them.
The brightest, thickest part is towards the centre of the galaxy, in the direction of Sagittarius, which from the UK never climbs far above the southern horizon. What stands overhead here in late summer is the stretch running out through Cygnus, further along the arm.
The numbers
- What it is
- A barred spiral galaxy
- Stars in it
- Somewhere between 100 and 400 billion
- Width
- About 100,000 light years
- Our distance from the centre
- About 26,000 light years
- One orbit for the Sun
- About 230 million years
- Best months from the UK
- June to September
To find out whether it is up tonight, and when it gets properly dark where you are, see Sky Tonight.