Ethereal

When:

Lookups spiked on April 19, 2013.

Why:

NASA released a new photograph of the Horsehead Nebula – an image of gas and space dust that various commentators described as "ethereal."

Ethereal means not only "celestial" or "heavenly," but also "marked by unusual delicacy or refinement."

Ethereal comes from ether, which traces back to the Greek word meaning "to ignite" or "to blaze." In ancient times, the sky and outer space were thought to consist of air that had been purified by fire. Since the gods lived in the heavens, this was the air – the "ether" – they breathed. This "heavenly" atmosphere of the gods became the basis for our modern sense of ethereal.