Jupiter, Saturn in ‘great conjunction’ on Dec. 21 – the closest since 1623

Published December 9, 2020, 12:40 PM

by Ellalyn De Vera-Ruiz

The universe’s biggest planets Jupiter and Saturn are putting on a rare show this month, as they move close to each other in an astronomical event called “great conjunction.”


The National Aeronautics and Space Administration (NASA) said Jupiter and Saturn have been waltzing their way together all year but they will appear increasingly closer together by around one-fifth of a full moon apart on December 21, the closest they have gotten in the past two decades.

The Dec. 21 event brings the closest Jupiter-Saturn conjunction since 1623, during Galileo’s times, said The Old Farmer’s Almanac, North America’s most popular reference guide.

The Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAGASA) said Filipinos will have the opportunity to view this rare event of Jupiter and Saturn standing close together.

It noted that the giant planets will lie among the background stars of the constellation Sagittarius, the archer, with magnitudes -2.0 and 0.6, respectively.

“To view the atmospheric features of these two planets, satellites and rings will require a modest-sized telescope under a dark and clear sky condition,” PAGASA said.

Jupiter and Saturn can been seen about 36 and 34 degrees in the southwestern horizon, it added.

The Jupiter-Saturn great conjunction occurs only every 20 years during this century, according to NASA.

A New York Times report cited that the Jupiter-Saturn alignment on Dec. 21, 2020 is a special one as it will be the closest one since 1623.

NASA pointed out that the “greatest” great conjunction between Jupiter and Saturn may not be happening again for the next 60 years, as the two planets will likely appear again in a very close distance between each other until 2080.

Simultaneous with the Jupiter-Saturn great conjunction this year is the winter solstice.

PAGASA said the sun will be reaching the winter solstice on December 21, which means Philippine nights will begin to be longer than daytime.

The winter solstice signals the earth’s completion of another annual circuit around the sun, it explained.

“This marks the time when the Sun lies at its farthest point south of the equator. It signals the onset of winter in the Northern Hemisphere and summer in the Southern Hemisphere,” PAGASA said.