2020, December 15-21: Great Conjunction

By Jeffrey L. Hunt on December 14, 2020 • ( 0 )

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2020, December 15: The razor-thin crescent moon appears very low in the southwest after sunset.

During the next week Jupiter approaches and passes Saturn for their once-in-a-generation Great Conjunction on December 21, 2020.

On December 15, the razor-thin appears to the lower right of Jupiter and Saturn after sunset. The planets are 0.6° apart.

2020, December 15: In the southwest as night falls, Jupiter is 0.6° to the lower right of Saturn.

A little later as the sky darkens further and the moon sets, the planets are visible together low in the southwest.

2020, December 16. The moon joins Jupiter and Saturn days before the Great Conjunction of 2020.

Just 5 days before the conjunction the crescent moon shines beneath the converging planets. The planet gap is 0.5°, the apparent diameter of the moon in the sky. For the next several evenings, your pinky finger at arms length covers both planets.

2020, December 17: After sunset, Jupiter and Saturn are in the southwest. The moon is to the upper left of the planet pair.

December 17, the crescent moon appears to the upper left of the converging planets. The planets are 0.4° apart.

2020, December 18: The crescent moon is over 20° to the upper left of Jupiter. The Jupiter – Saturn gap is 0.3°.

The moon is to the upper left of the planets. The gap between Jupiter and Saturn is 0.3°.

2020, December 19: As night falls, the moon is in the south-southwest with Jupiter far to its lower left. Bright Jupiter is 0.2° to the lower right of Saturn. The moon is 4.5° to the right of Delta Aquarii (δ Aqr).

The waxing gibbous moon is to the upper left of the impending conjunction. Bright Jupiter is 0.2° to the lower right of Saturn.

2020, December 20: In the southwest after sunset, Jupiter is 0.1° below Saturn.

One night before the conjunction, Jupiter is below Saturn.

A conjunction occurs when two planets have the same celestial longitude.

Jupiter passes Saturn during daylight hours in North America and South America when they share the same celestial longitude – the definition of a conjunction. By nightfall the planets are still close in the southwest after sunset.

2020, December 21: The Great Conjunction of 2020. Jupiter appears 0.1° to the lower left of Saturn.

Conjunction evening! Jupiter is immediately to the lower left of Saturn.

Jupiter and Saturn are close enough to appear together through a telescope’s low power eyepiece. Saturn’s rings and Jupiter’s four brightest and largest moons are visible as well.

Through a small telescope or spotting scope, both planets appear in the same field of view. Jupiter’s four largest moons and Saturn’s moons are easy to see.

A binocular may reveal some of the Jovian moons.

The planets are visible as separate “stars” to the unaided eye. They do not merge into a single point or suddenly brighten.

During the next week, watch the Jupiter move away from Saturn.