Jupiter gives us Pluto in 2020

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Jupiter gives us Pluto in 2020

 

 

Jupiter and Pluto stay close on the sky’s dome throughout 2020, presenting perhaps the best Jupiter-Pluto alignment for centuries to come. On May 12, the moon sweeps to the south of Pluto

 

around 6 UTC, and then some four hours later, swings south of Jupiter around 10 UTC. The 2nd of 3 Jupiter/Pluto conjunctions will occur on June 30.

 

The king planet Jupiter is as hard to miss with the eye alone as the dwarf planet Pluto is difficult to find with the telescope. Jupiter is bright! It ranks as

 

the fourth-brightest celestial object to light up the heavens, after the sun, moon and planet Venus. Pluto, on the other hand, is faint. It’s about 1,600

 

times dimmer than the faintest star visible to the unaided eye. It’s true that the best time of year to see Pluto through a small telescope is around the

 

planet’s yearly opposition, when Earth is going between Pluto and the sun. That’ll happen this year on July 15-16, 2020.

 

However, this year – 2020 – is exceptional for Jupiter and Pluto. These two worlds are having a triple conjunction. They’ll come together, move apart, and

 

come together again three times in 2020. The first conjunction took place on April 5. The second one will come on June 30, and the final one on

 

November 12. Because all of these Jupiter-Pluto conjunctions happen when these two planets are actually visible in our night sky (as opposed to being

 

lost in the sun’s glare), this year’s Jupiter-Pluto alignment may be the best for centuries to come.

 

This year, very bright Jupiter and very faint Pluto will remain near each other throughout the year, closely aligned in front of the constellation Sagittarius.

 

Pluto requires a telescope to be seen. No telescope? Try NASA’s Night Sky Network to find star parties and/or astronomy clubs near you. And you don’t

 

need a telescope to use your imagination. Throughout 2020, dazzling Jupiter will enable us to envision Pluto with the mind’s eye on the sky’s dome. First

 

find Jupiter and – presto – you’ve nearly stumbled upon Pluto. Just remember, Jupiter outshines Pluto by several million times.

 

Where are these worlds now? Both Pluto and Jupiter came out from behind the sun in January 2020, and then hovered low in the east before sunrise.

 

Now – in May 2020 – these two worlds come up around midnight (midway between sunset and sunrise) at mid-northern latitudes, and at late evening

 

for the Southern Hemisphere. Jupiter and Pluto climb upward throughout the nighttime morning hours, to reach the meridian at or near dawn on these

 

May 2020 mornings

 

 

View larger. | Use the waning moon to catch the morning planets – Jupiter, Saturn and Mars – from May 11 to 14, 2020. Pluto is up there, too, near

 

Jupiter, but it’s much too faint to view with the eye alone and very tough to catch in the moon’s glare, even with a telescope. On May 12, the moon

 

sweeps to the south of Pluto around 6 UTC, and then some four hours later, swings south of Jupiter around 10 UTC. The 2nd of 3 Jupiter/Pluto

 

conjunctions will occur on June 30. Read more about the view on May 12 from Guy Ottewell or from EarthSky’s Bruce McClure.

 

Of course, although Jupiter and Pluto nearly align along the same line of sight throughout 2020, these two worlds aren’t close together in space. Jupiter

 

is a bit more than 5 astronomical units (AU) from the sun, while Pluto lodges way beyond Jupiter, in the Kuiper Belt, at about 34 AU from the sun. One

 

astronomical unit (AU) = one sun/Earth distance.

 

 

Two planets are said to be in conjunction whenever they reside north and south of one another on the sky’s dome. Conjunctions of Jupiter and Pluto recur in periods of 12 to 13 years. The

 

previous Jupiter-Pluto conjunction happened on December 11, 2007, and the one before that on December 2, 1994. After 2020, the next Jupiter-Pluto conjunction will occur on February 4, 2033,

 

and the one following that on April 12, 2045. But the gap between Jupiter and Pluto at each one of these conjunctions is quite far apart, and the conjunctions of 1994, 2007, and 2033 happen so

 

close to the sun that even Jupiter is lost in the sun’s glare.

 

Far and away, 2020 presents the best alignment of Jupiter and Pluto in the 21st century (2001 to 2100). What’s more, Jupiter and Pluto stage three conjunctions this year, as Jupiter passes less than

 

one degree north of Pluto at each conjunction on April 5, June 30 and November 12, 2020. (For reference, the moon’s angular diameter spans about 1/2 degree of sky.) All of these conjunctions in

 

2020 take place in front of the constellation Sagittarius, with Jupiter first passing Pluto on April 5 in prograde (going eastward in front of the backdrop stars), then sweeping past Pluto on June 30 in

 

retrograde (going westward relative to the background stars), and then for the final Jupiter-Pluto conjunction on November 12 in prograde (eastward).

 

 

All three Jupiter-Saturn conjunctions on April 5, June 30 and November 12, 2020 take pace place in front of the constellation Sagittarius, not far from the 5th-magnitude star 56 Sagittarii.

 

Constellation chart via International Astronomical Union (IAU).

 

Most of the time, a Jupiter-Pluto conjunction in any year is a solitary event, as Jupiter laps Pluto going eastward, and never looks back. Triple conjunctions of Jupiter and Pluto – which occur over a

 

period of about 7.4 months – are rare because Jupiter has to first catch Pluto going prograde (eastward), then in retrograde (westward) and then in prograde (eastward) again. The three-peat

 

performance last happened in 1955-56 (November 2, 1955; February 8 and June 16, 1956), and will next occur in 2106-07 (July 13 and November 2, 2106; February 19, 2107). Yet, all three

 

conjunctions in 1955-56 were widely spaced, and all three conjunctions in 2106-07 will be widely spaced, too.

 

 

Illustration showing why a superior planet appears to go in retrograde (westward in front of the backdrop stars of the zodiac). As seen from the north side of the solar system, all the planets orbit

 

counter-clockwise. When the faster-moving Earth goes by a slower-moving superior planet, that planet appears to go backward (in retrograde). In 2020, Mars is in retrograde from September 9 to

 

November 15, Jupiter from May 14 to September 13, and Saturn from May 11 to September 29. Image via Wikimedia Commons.

 

In other words, as we said above, 2020 may well showcase the best Jupiter-Pluto alignment for centuries to come. Most excitingly, both Jupiter and Pluto will reach opposition in mid-July 2020. At

 

opposition, a superior planet – any planet revolving around the sun outside of Earth’s orbit – resides opposite the sun in Earth’s sky.

 

 

Opposition happens when Earth flies between a superior planet, like Mars, and the sun. This happens yearly for most of the outer planets (and every other year for Mars). Illustration via Heavens-Above.

At opposition, a superior planet (or superior dwarf planet) rises at sunset and sets at sunrise, and is out all night long. It’s at opposition that a planet shines at its brightest best in Earth’s sky, and

 

it’s at or near opposition that a planet comes closest to Earth for the year.

 

    Jupiter reaches opposition on July 14, 2020, at about 8:00 UTC, and comes closest to Earth on July 15, 2020, at about 10:00 UTC.

 

    Pluto reaches opposition on July 15, 2020, at about 19:00 UTC, and comes closest to Earth on July 13, 2020, at about 9:00 UTC.

 

In an uncanny bit of timing, the oppositions of Jupiter and Pluto happen almost concurrently in mid-July 2020. A planet reaches opposition midway through a retrograde. However, since Pluto

 

resides so much farther from the sun than Jupiter does, Pluto’s retrograde lasts nearly 1 1/2 months (six weeks) longer than Jupiter’s four-month retrograde. So for near-unison oppositions, Pluto’s

 

retrograde has to start – and end – approximately three weeks before – and after – Jupiter’s retrograde.

 

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