The shortest day of the year is going to pack a big show. On Monday, as the Northern Hemisphere marks the beginning of winter with the solstice, we're also being treated to a rare and spectacular sight in the sky: a great conjunction of Jupiter and Saturn.
During the show, the two largest planets in our solar system will appear very close to one another, as if they were overlapping to create a double planet. The last time we were treated to such a sight was during the Middle Ages -- almost 800 years ago.
Some associate it with the fabled Star of Bethlehem that guided the three wise men in the Bible's Nativity story.
To celebrate the first day of winter and the great conjunction occurring on the same day, Google has created an animated Doodle showing Saturn giving Jupiter a high-five as it slides on by in its solar system orbit.
A conjunction occurs when any two astronomical objects appear close together in the sky when observed from Earth. From our perspective, the two giant planets will appear only a tenth of a degree apart, even though they are actually about 450 million miles apart.
The conjunction of the two planets occurs every 19.6 years, but is the first time since 1226 that the pair aligns at night and Earthlings were able to witness it.
The close alignment will be easily visible to the naked eye while looking into the southwest sky just after sunset.