'Great Conjunction': Earthlings treated to rare alignment of Jupiter and Saturn

FILE PHOTO: One of the last looks at Saturn and its main rings from a distance as captured by Cassini. NASA/JPL-Caltech/Space Science Institute/Handout via REUTERS

NEW YORK (Reuters) - The sky over the Northern Hemisphere will feature a once-in-a-lifetime light show on Monday night as the solar system's two biggest planets race across the firmament and appear to meet in a celestial event that astronomers call the "Great Conjunction."

The spectacle is a near convergence of the orbits of Jupiter and Saturn that coincides with Monday's winter solstice, the shortest day of the year. The conditions will make the two frozen-gas spheres appear closer and more vibrant than at any time in 800 years, assuming the skies are clear.