MADISON (WKOW) – What has come to be known as the “Christmas Star” is a vibrant planetary conjunction that is easily visible in the evening sky as the bright planets Jupiter and Saturn converge on the night of December 21.
According to NASA, Italian astronomer Galileo Galilei turned his telescope to the night sky in 1610 and discovered Jupiter’s four moons: Io, Europa, Ganymede, and Callisto. Galileo also discovered a strange oval around Saturn that was later determined to be his rings.
Thirteen years later, the solar system’s two gigantic planets, Jupiter and Saturn, traveled together through the sky. Jupiter overtook and eventually passed Saturn, in an event known as a “Great Conjunction.”
The planets pass each other regularly in the solar system, with their positions aligned about once every 20 years.
What makes this year’s spectacle rare is the fact that it has been nearly 400 years since the planets passed this close to each other in the sky, and nearly 800 years since the alignment of Saturn and Jupiter occurred at night.
According to NASA scientists, the closest alignment will be only one-tenth of a degree apart and will take a few days.
On Monday, December 21, they will appear so close that a pinkie finger at arms length can easily cover both planets in the sky.
The planets will be easy to see with the naked eye by looking southwest just after sunset. It is best to find a field or park to view.