The last time a sight such as this occurred was in 1226, and the next sighting will be around 2080.
For the first time since the Middle Ages, a rare astronomical alignment will create an uncommonly brilliant light in the sky. It is being compared to the Star of Bethlehem which guided the Magi to the newborn Jesus.
The phenomenon will take place on December 21, the winter solstice, when Jupiter and Saturn draw close together to create a unique spectacle in the sky.
A report from Forbes explains that conjunction between Saturn and Jupiter occurs once every 20 years. What makes this year’s conjunction unique is the position of the Earth, which will make the two planets appear even closer than usual. In the days leading up to the solstice, the planets will be visible and seem to approach each other.
On December 21, the conjunction will be most visible in North America just after dusk. On that night, the two planets will appear so close together that they will seem as one enormous mass. The display will create an extraordinary amount of light that will rival that of the full moon.
When to watch
In a statement published by Rice University, Astronomer Patrick Hartigan noted that the last time Jupiter and Saturn were so closely aligned was March 4, 1226. He explained that the “double planet” will be most easily viewed above the southwestern horizon. Hartigan said:
“By the time skies are fully dark in Houston, for example, the conjunction will be just 9 degrees above the horizon,” Hartigan said. “Viewing that would be manageable if the weather cooperates and you have an unobstructed view to the southwest.”
The Rice University report went on to note that the conjunction will be most clearly seen for 20-30 minutes after twilight. Hartigan advised stargazers in New York and London to have their viewing spots picked out early, so as to witness the event before it sinks below the horizon. The further north viewers are located, the less time they will have to witness the event.
The date of this conjunction is so close to Christmas that many are comparing it to the Star of Bethlehem, which guided the Magi to the site of the Nativity. While the biblical narrative does not give any indication as to the origins of this guiding star, Mark Collins of News4Jax muses that it could have been a supernova, or perhaps even a triple conjunction of Jupiter, Saturn and Venus.
For those who miss it, the next time this event will occur will be in 2080.