Saved on this device

Follow your curiosity

What discovery has been shared with you?

FACTREE gives you something interesting to discover every day — and something worth talking about together.

Start with one fact. Explore it, go deeper, then follow whichever branch catches your imagination.

Choose subjects for a surprise

Exploring any topic

Begin your discovery

Your next discovery is one click away.

Choose one or more subjects above, or leave Any Topic selected and let curiosity decide.

Astronomy

Dark Matter (in Space)

Quick fact

Dark matter is about five times more abundant than ordinary, visible matter, but it doesn't interact with light or any electromagnetic radiation – that's why it's 'dark'.

Why this is interesting

You know the stars and galaxies you see in the night sky? They are only the visible tip of a cosmic iceberg – most of the universe's matter is completely invisible, yet its gravity shapes everything we see. What is this hidden substance, and how do we know it's there?