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:
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 (whenthecurveslineup.com) 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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