Cometary knots and slime mould

Photo credit: Jan Faix
Hannover Medical School
Germany
www.mh-hannover.de

Dictyostelium is an amazing creature that can live both as single cells and huge cellular clumps or ‘slugs’. When there is plenty of food, cells graze independently, but when stocks decline they clump together forming exquisite spiral patterns. Cells have many fine filaments projecting from their surface (pictured) that help them to move quickly in response to environmental changes.

Photo credit: Robert O'Dell/Kerry P Handron
Rice University, Texas
USA
www.nasa.gov

These finger-like projections are cometary knots, part of the Helix nebula. The heads of each projection are each at least twice the size of our solar system. The tails stretch another 100 billion miles. Astronomers think the knots formed through gases colliding at different temperatures. Over time, the knots will most likely dissipate into the dark, cool interstellar space surrounding them.