Jupiter is at opposition on August 19th. If we take the long view — 12 years long — we can watch Jupiter’s oppositions as it passes through the zodiac constellations.

Jupiter will be at opposition on August 19th among the dim stars of the constellation Aquarius. When at opposition Jupiter appears directly opposite the Sun as seen by us on Earth — which means it’ll be at its biggest and brightest of the year. (Saturn came to opposition on August 2nd.)

Jupiter opposition diagram
At opposition, Jupiter and the Earth line up on the same side of the Sun.
Bob King

At times like these, it’s interesting to think about what’s actually happening. After all, everything in space is moving all the time, so there’s more going on than Jupiter crossing an invisible finish line. Jupiter is on average five times farther from the Sun than Earth, and it takes much longer to complete an orbit than our planet does, 12 years to our 1 year. So, another way to think of opposition is that Earth is catching up with and speeding past Jupiter, like runners on an enormous race track. Put another way, we reach opposition with Jupiter as we pass it by.

Since Jupiter moves through 1/12 of its orbit per year, it takes a year, plus time for the 1/12 of an orbit Jupiter has moved, for us to catch back up with it. This means we reach opposition with Jupiter about every thirteen months.

On August 20, 2021, Jupiter is at opposition just off the limb of Capricornus (which puts it within the boundaries of the Aquarius constellation.)

This pattern gives us a chance to use Jupiter as our guide for a 12-year observing project. I know this sounds a little absurd but all you need to do is remember to look up. Let’s start this week.

Jupiter is bright and easy to find, except when it's near conjunction and is either too close to the Sun to see or is tough to spot through the bright sunlight. So, let’s keep an eye on it as much as we can. As the leaves change and fall, as the snow piles up, melts, and the leaves come back, let’s watch Jupiter. As neighborhood kids laugh one day and learn to drive the next, and as a little more gray creeps onto our heads, we can watch whenever we have a chance. Where is Jupiter? What stars are nearby? What deep sky objects?

Through the Zodiac

These are the next 12 oppositions and the constellations Jupiter will be in for each one:

  1. August 20, 2021: Aquarius
  2. September 26, 2022: Pisces
  3. November 1, 2023: Aries
  4. December 6, 2024: Taurus
  5. January 9, 2026: Gemini
  6. February 10, 2027: Leo
  7. March 13, 2028: Virgo
  8. April 13, 2029: Virgo
  9. May 14, 2030: Libra
  10. June 16, 2031: Ophiuchus
  11. July 20, 2032: Sagittarius
  12. August 25, 2033: Back in Aquarius

As time goes on, we can see and imagine Jupiter’s moons and striped clouds sweeping through the stars. As the year goes on, our view of the solar system — and on the galaxy — changes, pointing in different directions, in the same way that we see Orion and Auriga in winter, and Aquila and Delphinus in summer.

When Jupiter comes back to Aquarius in August of 2033, we’ll have watched it through an entire one of its years. Can you imagine where we’ll be then? Who will win those World Series? What diseases will we cure? Will crews make it to Mars? Will we finally get those flying cars?

During all that time, we’ll have seen Jupiter move eastward among the background stars of all of the zodiac constellations, by about one constellation per opposition. (You’ll notice in Cancer, Scorpius and Capricornus are missing from the list. Jupiter crosses them, but not near an opposition. Also, Virgo is the largest zodiac constellation, so it takes longer to cross.)

If we have more time, we can try the same thing with Saturn. It takes about 29 years to take the same path through the stars. Each opposition is separated by a year plus about two weeks. Watching Uranus through its 81-year orbit would be remarkable, a lifetime of sky-watching.

To do the same with Neptune (165 years), Pluto (238 years), or more distant objects, we’d need some help from an immortality potion. But just imagine where humanity will be in that distant future if we were to start watching today.

It seems like an enormous commitment, but let’s give this a try. I hope you’ll add Jupiter to your list and start this week!

Tags

Jupiter

Comments


Image of Rod

Rod

August 21, 2021 at 11:43 am

This is cool 🙂 I had not thought about this before, good report.

You must be logged in to post a comment.

Image of Scott Levine

Scott Levine

August 21, 2021 at 9:06 pm

Thanks, Rod. I'm really glad you liked this one. Thanks for reading and letting me know. 🙂

You must be logged in to post a comment.

Image of Science

Science

August 21, 2021 at 12:03 pm

I enjoyed your article; very good. I was the curator of a major planetarium for 41 years. As a part of the job, I, of course, kept up with the motions of the planets and always knew where they were in the sky. I was aware of this relationship but never thought that much about it.. Now that I have thought about it, I realize that I watched about 3 and a half of them. I should have paid more attention. I also remember, when just starting my adventure in astronomy, seeing Jupiter for the first time and knowing what it was--it was just in front of Scorpius. I have used a planetarium computer program to run back time and determined this must have been the summer of 1959 when I was just 14 years old. I always remember this anniversary whenever Jupiter returns to, at least approximately, this location as it did in 2018. Hopefully I'll be able to celebrate again in 2030.

You must be logged in to post a comment.

Image of Scott Levine

Scott Levine

August 21, 2021 at 9:12 pm

Wow... amazing, thanks for your comment. When I first started thinking about this pattern, myself, I remembered back to learning how to see Jupiter at the Vanderbilt Planetarium on Long Island, NY. I couldn't have been more than eight years old. Stellarium tells me it was in Virgo then. It's really something to look back and remember where we were at these moments.

Thanks for reading, and for your kind words.

You must be logged in to post a comment.

Image of Glenn

Glenn

August 22, 2021 at 9:54 pm

As we age we muse on the planets' motions. Jupiter's near 12 year cycle means oppositions after 12 years come some 4 to 7 days later in the month. But after 6 cycles or a "lifetime"of 72 years it is a month ahead. From June 18th 1964 to July 21st 2032 is 6 cycles but now the May 1963 date has crept forwards to be on June 18th again.

You must be logged in to post a comment.

Image of Glenn

Glenn

August 22, 2021 at 10:05 pm

Oops that should be 1960 June 19th.And May 1959. Must be those 72 years. LOL

You must be logged in to post a comment.

Image of Andrew James

Andrew James

August 21, 2021 at 9:51 pm

I do appreciate the gentle nature here to explain this to novices, but more detail needs to be stated - even as a note. Saying "Since Jupiter moves through 1/12 of its orbit per year, it takes a year, plus time for the 1/12 of an orbit Jupiter has moved, for us to catch back up with it. This means we reach opposition with Jupiter about every thirteen months." This should really say "...about 1/12"

Jupiter's orbital period is 11.8626 years not exactly 12 years as the article implies. This is roughly 11 years 10 months 11 days or about 4332 days against the 12 years or about 4383 days. His synodic period is 398.88 days or 398.88/365.26 or 1.092 years or 1 year 33.6 days.

Also Jupiter true orbit is slightly eccentric so the mean distance is slightly variable. Closest approach (periapsis) occurs on 23rd Jan 2023 (& 3rd Dec 2034) and next furthest (apapsis) on 29th Dec 2028. The very best at opposition date when Jupiter is largest will be 26th September 2022 at 49.88 arcsec. Opposition on 13th April 2029 will be smallest at 44.31 arcsec (an 11.8% difference.) By distance the variation is 591.5 to 665.5 million kilometres, averaging c. 628 million km. By coincidence, 2021 opposition is nearly exactly 600 m.km. (600.37 m.km. actually)

IMO Saturn's orbit is traditionally for more profound, as it marks 'father time' - youth, middle age, and old age - three orbits per average lifetime.

You must be logged in to post a comment.

Image of Andrew James

Andrew James

August 21, 2021 at 10:22 pm

Note: All this is testable using JPL Horizons here.[1].

To get a Table of opposition dates to the nearest day, input the step size in hours NT days e.g. 398.88x24 or 9573 hours. This improves the accuracy. Summary of results.

************************************************
DATE Vis. Dia Dist Con
mag arcsec AU
************************************************
2021-Aug-20 00h -2.9 49.12 4.0132 Cap
2022-Sep-22 21h -2.9 49.86 3.9541 Psc
2023-Oct-26 18h -2.9 49.43 3.9881 Ari
2024-Nov-28 15h -2.8 48.10 4.0990 Tau
2026-Jan-01 12h -2.7 46.48 4.2414 Gem
2027-Feb-04 09h -2.6 45.14 4.3674 Leo
2028-Mar-09 06h -2.5 44.38 4.4426 Leo
2029-Apr-12 03h -2.5 44.31 4.4491 Vir
2030-May-16 00h -2.5 44.96 4.3852 Lib
2031-Jun-18 21h -2.6 46.22 4.2650 Oph
2032-Jul-21 18h -2.8 47.83 4.1215 Sgr
2033-Aug-24 15h -2.9 49.26 4.0023 Aqr
************************************************

You must be logged in to post a comment.

Image of Andrew James

Andrew James

August 21, 2021 at 10:29 pm

e.g.
DATE = 2021-Aug-20 00h
Visual Magnitude. = -2.9
Diameter (arcsec) = 49.12
Distance (AU) = 4.0132 (or 600.366 m.km.)
Constellation = Cap

You must be logged in to post a comment.

Image of misha17

misha17

August 28, 2021 at 1:46 am

the ".8626 year" fraction in Jupiter's orbital period is about 6/7 (.8571) of a year. so 7 Jovian orbital periods is 83.082 years. The recent opposition occurred on Aug 19 (2021) at 17:50 PDT

According to In-The-Sky.org
( https://in-the-sky.org/search.php?searchtype=News&s=&startday=22&startmonth=2&startyear=2021&endday=31&endmonth=12&endyear=2299&ordernews=ASC&satorder=0&maxdiff=7&feed=outerplanets&objorder=1&distunit=0&magmin=&magmax=&news_view=normal&distmin=&distmax=&satowner=0&satgroup=0&satdest=0&satsite=0&lyearmin=1957&lyearmax=2021&objtype_4=1&objtype_5=1&objtype_6=1&objtype_7=1&objtype_8=1&objtype_9=1&objtype_11=1&objtype_12=1&objtype_13=1&objtype_14=1&objtype_15=1&objtype_17=1&objtype_18=1&page=83 ),
there will be a similar opposition in 83 years on 19 AUG 2104 at 10:50 PDT

You must be logged in to post a comment.

Image of Tony

Tony

August 22, 2021 at 3:03 pm

Given Jupiter's roughly 12-year orbit, and Venus' 8-year cycle, we can expect similar Venus-Jupiter conjunctions every 24 years. But with the giant's orbital period of more precisely 11.86 years, it will be slightly farther east in exactly 12 years or multiple thereof, and the 24-year conjunction will happen a bit later in the season . . . if it happens at all.

In a few months we'll be at the 48th anniversary of a particularly notable Venus-Jupiter apparition which got extra attention due to the close proximity of Comet Kohoutek. It came after a series of Venus-Jupiter conjunctions which included November 18, 1901 (Saturn was very close by), November 25, 1925, and December 6, 1949. In each case a second Venus-Jupiter conjunction happened after Venus went retrograde in anticipation of inferior conjunction. But in 1973, Venus reached its stationary point before it could catch Jupiter; there was no true conjunction between them and we witnessed a quasi-conjunction instead.

In 2021, Jupiter is well to the east of its corresponding 1973 position, and Venus will get nowhere near. But Saturn will be in almost the exact spot that Jupiter occupied 48 years ago. Venus won't appear as close to Saturn as Jupiter did in 1973, because every 8 years the stationary points (and solar conjunctions) of Venus happen slightly farther to the west -- about 2 days earlier.

You must be logged in to post a comment.

Image of misha17

misha17

August 28, 2021 at 1:34 am

Another example of the 24-year Venus/Jupiter cycle are the close evening conjunctions of August 1991 and August 2015. As with the 1973 apparition that Tony mentioned, the next event in the August Venus/Jupiter apparitions in August 2039 is not a true conjunction, as Venus will begin retrograde before it "catches" Jupiter.

You must be logged in to post a comment.

Image of Andrew

Andrew

August 22, 2021 at 11:05 pm

Very cool!!

You must be logged in to post a comment.

Image of Zubenelgenubi 61

Zubenelgenubi 61

August 23, 2021 at 7:34 pm

A couple of minor but noticeable errors: The orbital periods of Uranus and Pluto are 84 and 248 years, respectively, not 81 and 238.

You must be logged in to post a comment.

Image of Tom Kellogg

Tom Kellogg

August 24, 2021 at 4:57 pm

Thanks Scott for the helpful article on Jupiter. An additional factor is when Jupiter is closest to the sun (perihelion) which is January 2023. Around that time is is 10% closer that when it is most distant from the sun, around 6 years before and after January 2023. This means the oppositions 9/26/22 and 11/1/23 will be nearly 10% or 47 million miles closer than 6 years before and after. For us in the Northern hemisphere oppositions that are closer to winter equinox places Jupiter higher in the sky which further improves clarity when looking through the telescope so I am eagerly anticipating opposition in November 2023.

You must be logged in to post a comment.

You must be logged in to post a comment.