# What is dark matter?

Galaxies spin and cluster as if there were much more mass than the matter we see. What that mass is has not been found, and the cosmic web is shaped by it.

Connects to:
- [The cosmic web](https://mapideas.org/i/as_web)
- [The expanding universe](https://mapideas.org/i/as_expansion)

Sources:
- [Wikipedia: Dark matter](https://en.wikipedia.org/wiki/Dark_matter)

Source: https://mapideas.org/i/q_astro_dark · open on the map: https://mapideas.org/#q_astro_dark