Monday, September 19, 2022

A Jupiter Opposition To Remember For The Next 109 Years


                   Jupiter in the C-14 telescope of Harry Bayley Observatory

Jupiter’s opposition and closest approach to Earth fall on the same day this year, setting the stage for a spectacular astronomical event. That’s because this opposition takes place so close in time to Jupiter’s perihelion.  Recall first the meaning of a planetary opposition:  The position of a superior planet (i.e. beyond the Earth’s orbit) when it lies on the extension of the line joining the Earth and the Sun. The planet is therefore diametrically opposite to the Sun in the sky and rises when it sets.

This can be discerned from the diagram below:

Here the Earth is planet p1 and Jupiter, p2, set for two different oppositions at different times.  The opposition we are discussing for Jupiter here is indicated in the lower alignment, with perihelion point identified.  If it’s closest (or nearly so) to the Sun, and Earth at p1  is between it and the Sun, the it’s a close opposition for us. The juxtaposition of Jupiter’s opposition in late 2022, and perihelion in early 2023, brings the planet closer to earth at this opposition than it has been for 70 years.

Recall perihelion is the planet's closest point to the Sun in its elliptical orbit.

Currently, Jupiter becomes prominent in the eastern sky after sunset and crosses the sky overnight, remaining visible in the western sky at sunrise. It will rise above the eastern horizon later and later in the evening until it reaches opposition on Sept. 26, when it will rise right at sunset.  Bear in mind, rise at sunset.  That is close to the best time to look for it, either with good (e.g. 7 x 50mm) binoculars or small telescope.  We definitely plan to be out with our Tasco 60mm (2.4 in.) aperture refractor.  That scope will show the biggest planet about like seen here:

According to Jeffrey Hunt, a retired Illinois planetarium director whose website ( tracks celestial events for amateur sky gazers, Jupiter has grown 2.5 times brighter than it was last spring when it was in a position of “super conjunction,” meaning it was on the opposite side of the Sun in relation to Earth.  The diagram below shows that alignment in relation to the opposition in the orbit:

 By way of comparison, during April, Jupiter was 5.9 times Earth’s distance to the Sun from us, measured in A.U. or Astronomical Units. Recall that 1 A.U. =  = 1.496 x 108 km and is equivalent to the average distance between the Earth and the Sun. At the coming opposition, the separation (will be) reduced to 3.9 times the Earth-Sun distance.

Miss this event and you will have to wait until the year 2129 to see anything remotely comparable.  Just be sure you're on a great life extension program.

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