Thursday, 24 December 2020

Jupiter and Saturn form the closest visible alignment in 800 years


Jupiter and Saturn formed the closest visible alignment in 800 years.

The observatory at Gwacheon National Science Museum is where one can get close details on what's known as the "great conjunction".

Jupiter and Saturn seem to align every two decades, but the last time they came this close to each other was 400 years ago in 1623.

On that occasion, Jupiter and Saturn were too close to the sun, so the conjunction wasn't visible from Earth.

The next great conjunction will occur on the 15th of march 2080.

Because this event is happening just before Christmas, some are dubbing it the 'Christmas star.'

This event also happens to fall on the winter solstice, the longest night of the year.

A "great conjunction" is really a conjunction of the planets Jupiter and Saturn, when the 2 planets appear closest together in the sky. Great conjunctions occur approximately every 20 years when Jupiter "overtakes" Saturn in its orbit. They are named "great" for being by far the rarest of the conjunctions between naked-eye planets (i.e. excluding Uranus and Neptune).

The spacing between the planets varies from conjunction to conjunction with most events being 0.5 to 1.3 degrees (30 to 78 arcminutes, or 1 to 2.5 times the width of a full moon). Very close conjunctions happen much less frequently (though the maximum of 1.3° is still close by inner planet standards): separations of less than 10 arcminutes have only happened four times since 1200, most recently in 2020.

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