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

How the Cosmic Microwave Background Maps the Early Universe

Quick fact

The cosmic microwave background was discovered by accident in 1965 as a persistent hiss in a radio antenna that resembled pigeon droppings—yet it turned out to be the echo of creation.

Why this is interesting

You are literally bathed in the oldest light in the universe, a faint hiss of microwaves left over from just after the Big Bang. But how can that ancient flash hide a treasure map of everything that has ever existed?