The CRISPR enzyme (green and red) binds to a stretch of double-stranded DNA (purple and red), preparing to snip out the faulty part. Illustration courtesy of Jennifer Doudna/UC Berkeley hide caption

itoggle caption Illustration courtesy of Jennifer Doudna/UC Berkeley

The Cassini spacecraft has been taking radar images of Titan for years now. This modified image of the Ligeia Mare, a sea on Titan's north pole, is a composite of some of those. NASA/JPL-Caltech/ASI/Cornell hide caption

itoggle caption NASA/JPL-Caltech/ASI/Cornell

One of 30 copies of the first protoype meter made by the International Bureau of Weights and Measures (BIPM) in Sevres, France. 1875-1889 NIST Museum Collection hide caption

itoggle caption NIST Museum Collection

A high-resolution image of the molecular carrier that moves the botulinum toxin from the intestine into the bloodstream. The carrier (silver) creates gaps in the gut lining by grabbing the rope-like molecules (red ribbons) that tether one intestinal cell to the next. Rongsheng Jin, UC Irvine, and Min Dong, Harvard Medical School hide caption

itoggle caption Rongsheng Jin, UC Irvine, and Min Dong, Harvard Medical School

By comparing "Skull 17" from the Sima de los Huesos site with many others found in the same cave, researchers were able to discern the common facial features of the era. Javier Trueba /Madrid Scientific Films hide caption

itoggle caption Javier Trueba /Madrid Scientific Films

Andreas Fhager, a biomedical engineer at the Chalmers University of Technology in Sweden, adjusts the Strokefinder device on a test subject's head. Gunilla Brocker hide caption

itoggle caption Gunilla Brocker

Being a bit coldblooded has its charms, scientists say. A mammal the size of a T. rex, for example, would have to eat constantly to feed its supercharged metabolism — and would probably starve. Publiphoto/Science Source hide caption

itoggle caption Publiphoto/Science Source