Astronomy

2020, November 2: Jupiter – Saturn Heliocentric Conjunction

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2020, November 2: Jupiter passes Saturn in a heliocentric conjunction, as viewed from outside the solar system.

As the Great Conjunction of Jupiter and Saturn nears, Jupiter passes Saturn if viewed from the sun.

by Jeffrey L. Hunt

As Jupiter edges closer to Saturn in the evening sky of Earth, Jupiter passes Saturn as viewed from outside the solar system on November 2, 2020.  This is known as a heliocentric conjunction.  The next one for these two planets is on December 7, 2040.

If we were on Jupiter on November 2, we would say that Saturn is at opposition.  Saturn is in the opposite direction in the sky from the sun.  If we were Saturnians, then we would say that Jupiter is at inferior conjunction, between Saturn and the sun. Notice on the chart above that Earth is not close to the line of the heliocentric conjunction.

From these two planets in alignment, a question may develop about more planets appearing in a line from the sun. Astronomer Jean Meeus (Mathematical Astronomy Morsels, pp. 186-191) addresses the question.  Without reciting his reasons, the answer: “Never!” The dynamics of fast – moving Mercury to slow-moving Pluto (Yes, Pluto is one of the “Classic Nine” planets.), there is never a moment when all nine are in a line stretching from the sun.  He further notes that it’s impossible for even three to be in a line.  Reasonably they can be within a 60° angle of each other, 50° if Pluto is not included.

2020, November 2: Jupiter is 5.0° to the lower right of Saturn, about one hour after sunset. Look toward the south-southwest.

In our sky, the planets are 5.0° apart.  They can be found in the south-southwest about an hour after sunset on November 2.  Saturn is to the upper left of bright Jupiter. The planets are in front of the stars of eastern Sagittarius.  The famous “Teapot” shape is to the lower right of the planets.

The Great Conjunction occurs December 21, 2020.

Continue to watch Jupiter and Saturn, as the Jovian Giant moves in and passes the Ringed Wonder as viewed from our observing spot on Earth.

2020, December 8: Morning Crescent Moon with Leo

December 8, 2020: The thick crescent moon is in the southern sky before sunrise. It is near the star Denebola, the Lion’s Tail. At that time, Venus is in the southeastern sky among the stars of Libra.

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