Christmas Star: ‘Jupiter, Saturn combine for rare Great Conjunction

ORLANDO, Fla. – It is a celestial event hundreds of years in the making. Conjunctions are common and occur when objects come close together in space from our perspective. The Great Conjunction is rare.

The Great Conjunction occurs when Jupiter and Saturn come very close to each other from our perspective. However, not every Great Conjunction is created equal, which is what makes the combination that occurs during the winter solstice so rare and special.

“Each Great Conjunction has different angular separations, or the distances between the two planets can vary a little depending on how things line up,” said Seth Mayo, curator of astronomy at the Museum of Arts and Sciences in Daytona Beach.

The last time the two planets were so close to each other, from Earth’s point of view, was in 1623. “The problem with this Great Conjunction is that it happened close to sunset, so the sun’s glare most likely obscured the pair of planets . , ‘Said Mayo. “The last observable time these planets were so close was the year 1226.”

Because the planets will be so close together by Christmas, it is called the “Christmas Star” by some.

On December 21, the two gas giants will be only 0.1 degrees apart. To the naked eye, it will likely appear as two distinct points, rather than one “star,” but it depends on a person’s vision and atmospheric conditions.

If you have a telescope, the two planets will appear in the same field of view.

Also in that field of view will reside the largest moons of the two bodies. A telescope or binoculars are needed to see the moons.

After December 21, Jupiter and Saturn begin to move away from each other. This trend will continue for the next decade before the two giants come closer together again in the 2030s. This will set up the next Great Conjunction in 2040, although it won’t be as brilliant as 2020’s.

The planets won’t be that close again until 2080. In an extremely rare way, Jupiter completely covers Saturn. That won’t happen until 7541.

The Great Conjunction occurs because Jupiter is inside while orbiting the sun in our solar system. Since Jupiter’s orbit is smaller than Saturn’s, Jupiter moves faster around the Sun and overtakes the Ringed Planet. Think of it like a NASCAR race where the inner field is the sun. The car with the inner lane travels faster on the inner field than a car on the outside.

“In very rare cases, these great conjunctions between Jupiter and Saturn can occur several times a year, known as triple conjunctions, as Earth overtakes these planets with its much faster orbit,” Mayo said. “That won’t happen again until the time frame of 2238-2239, so we have a bit more to wait.”

The last time there was a triple conjunction was in 1981.

Seminole State College Emil Buehler Perpetual Trust Planetarium is organizing a “Great Jupiter / Saturn Combination Virtual Star Party”. It is a free event for everyone.

There are events on December 19 and 21.

More information is available at seminolestate.edu/planet.

Details:

When: December 21, 2020

True: Southwestern sky about 30 minutes. after sunset

Remarks: The planets will gradually move lower in the sky as the evening progresses, so the earlier the better.

You don’t need a telescope or binoculars to see, but they will enhance the viewing experience.

You’ll notice those two bright dots, Jupiter and Saturn are getting closer and closer every night until December 21st.