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 Stellar Winds Shape Planetary Nebulae

Quick fact

Some planetary nebulae are shaped like hourglasses or butterflies, elongated by fast winds that collide with slower outflows from earlier phases.

Why this is interesting

You may have seen stunning images of planetary nebulae with glowing rings and bipolar lobes—but why do they look so different from a simple sphere? The answer lies in the stellar winds blowing from the dying star.