x
  
  
Posted: 12/16/20

TAMIU Planetarium Explains How to Observe the ‘Christmas Star’ with Naked Eye

 

TAMIU Logo
Peter Davis  

On Monday, December 21, 2020, there will be a once-in-a-lifetime opportunity to see with the naked eye a conjunction of Jupiter and Saturn low in the southwestern night sky shortly after sunset, known as the “Christmas Star.”

Peter Davis, TAMIU Lamar Bruni Vergara Planetarium director, explained that a conjunction happens when two planets seem to pass close to each other as seen from Earth. As they revolve slowly around the Sun in the plane of the solar system, the planets appear to move through the sky along an imaginary line called the ecliptic. 

Jupiter and Saturn have not passed that close for 800 years.

“Conjunctions between planets happen every few decades, but on the night of December 21, Jupiter will pass within one-tenth of a degree of Saturn, close enough to see them in the same field of view in a telescope,” Davis said.

He continued, “You can see them for yourself by going outside after sunset and looking low in the southwest for the bright ‘star’ which is actually the planet Jupiter.  Saturn is already close to the upper left of Jupiter now. But by Monday night, December 21, these planets will seem to merge into one object as seen from Earth.” 

Jupiter is five times farther from the Sun than we are, while Saturn is 9.5 times farther away.  On Dec. 21,  Jupiter will move almost right in front of Saturn as it moves through the sky, Davis explained.

“You can watch them approach on the days before and then move apart after Monday night,” he said, “Since these planets set only a few hours after the Sun, you will need to go outside soon after sunset and find a place with an unobstructed view of the southwestern horizon that is free from bright lights.”

He continued, “Some astronomers think that a rare triple conjunction of Jupiter passing Saturn three times in 7 B.C. might have been the astronomical event that caused the wise men or kings (the Magi) to travel to see the newborn King Jesus. Conjunctions can occur more than once in a year because as the faster-moving Earth passes Jupiter it seems to back up for a short time, just as when you pass another car on the highway it seems to backup even though it is right beside you.

“This conjunction is a rare opportunity to witness something that may be similar to what brought the Magi to see Jesus,” Davis said,  “Even if that ancient event was something entirely different, this conjunction is worth checking out for yourself.”

For more information, contact Davis at 956.326.3128 or at peter.davis@tamiu.edu 

Masks are required on campus and social distancing is maintained at all times.

 The bright object in the bottom center of the image above shows this conjunction as it will appear in the night sky on Monday, December 21 in the southwest near the horizon. (View produced in Stellarium.)

The bright object in the bottom center of the image above shows this conjunction as it will appear in the night sky on Monday, December 21 in the southwest near the horizon. (View produced in Stellarium.)