Depletion of stratospheric ozone occurs over both hemispheres of the Earth. However, this phenomenon is significantly less severe in the northern hemisphere (Arctic) than in the southern hemisphere (Antarctica).

A device that delivers electric current to the knees could help combat osteoarthritis, a painful condition caused by worn cartilage, after successful tests in rabbits.

The various forms of painting throughout the ages explained.

Techniques and methods of painting frescos explained in detail.

After first appearing in the religious art of ancient Iran, the disc halo migrated across cultures at an astonishing pace, aided by trade on the Silk Roads. Matt Wilson explores how a simple symbol connects Jesus, Buddha and Apollo.