Astrocytes, like these in a slice from a rat brain, wrap the footlike ends of their branches around capillaries (arrow). The astrocytes collect nutrients from the bloodstream, which they pass on to neurons, and protect the brain from toxic agents.
Credit: Marie Simard

A neuron grown in culture without glia (above) shows many fewer synapses (bright dots) than a neuron cultured with glia does (below).
Credit: Ullian and Karen Christopherson

Hasse diagram for the divisors of 42.

Hasse diagram for a given poset and its corresponding geometric figure.

The shy green form of a desert locust nymph (right) can switch into a multicolored crowd lover if jostled.
Credit: Sword

Where the highest-energy cosmic rays graze the moon (light-gray area), microwaves may shoot Earthward.
Credit: Adapted from Peter W. Gorham/JPL

Ultraviolet light reveals kerogen-munching microbes (blue) surrounding fragments of organic material (orange) in this sample of New Albany shale.
Credit: Science

A fluorescent tag for a specific bacterial protein reveals a helical skeleton.
Credit: Carballido-López

Researchers reconstructed ancient climate patterns by using tree stumps such as this one in Southern Chile.
Credit: Roig

Annual temperature and rain variations are reflected in growth rings.
Credit: Roig

Graph shows the size of the cosmos over time as indicated by supernovas several billion light-years from Earth (white objects on right part of the curve) and the farthest known supernovas. If dust were dimming the nearby supernovas, the rate of expansion would fall instead along the orange dotted line.
Credit: Images: Space Telescope Science Institute/NASA

Supernova 1997ff (right) and the galaxy in which it resides (arrow at left).