01
Diameters, not precise boundaries
"Where the Milky Way ends" or "how big the Local Group is" doesn't have a sharp edge — these are commonly cited approximate diameters.
Universe · Question
How big is the universe, really?
Big numbers stop meaning anything after a while. This walkthrough takes it one zoom-out at a time — from your own height to the edge of the observable universe — so each jump in scale stays legible.
Visual model
Eight zoom-outs.
What's simplified
These are round numbers, not exact ones.
02
The universe may be infinite
93 billion light-years is the diameter of the observable universe — the part whose light has had time to reach us. The whole universe could be larger, or infinite.
Misconception check
Quick check.
Quick check
Go deeper
Keep exploring.
Next in this series →
Star life cycle ↗
Why stellar mass decides its ultimate fate.
Universe
What is a light-year?
The unit this whole ladder is measured in.
Home
Solar system model
Zoom back in to the interactive 3D solar system.