As early as Vera Rubin found that stars on the outskirts of galaxies move too fast — as if held by an invisible web. And Fritz Zwicky was the first to suspect that clusters of galaxies hide enormous invisible mass. Today we call it dark matter and try to understand what it's made of.

New simulations have revealed: if dark matter particles are capable of sticking together, they clump into dense blobs. A blob with the mass of a million Suns disturbs the stellar stream GD-1 — a long thread of torn-apart stars — like a speck stuck in a web. And the same blob exactly matches the properties of an invisible object found through a gravitational lens.

Moreover, sticky blobs of dark matter naturally gather stars around themselves. That's probably how the mysterious Fornax 6 cluster in the Fornax dwarf galaxy came to be.

And here's the twist: the same mechanism tied together three puzzles at once. And the GD-1 stream itself is so huge that it occupies more than a third of the celestial hemisphere — the invisible framework of the cosmos reveals itself on unexpected scales.