This image of Jupiter was taken by NASA's Cassini spacecraft on October 8, 2000. The Great Red Spot always stays in the south edge of the brownish South Equatorial Belt. South is up to match the view in many astronomical telescopes.
NASA / JPL / University of Arizona

Jupiter's most famous feature is its Great Red Spot (GRS). The spot was named around 1878 when it turned a vivid brick red, but in recent decades it has generally been a much less conspicuous pale tan. The Red Spot is a vast, long-lived storm, spinning like a cyclone. However, unlike low-pressure cyclones and hurricanes on Earth, the GRS rotates in a counter-clockwise direction in Jupiter's southern hemisphere, showing that it is a high-pressure system.

Of course there's a lot more to look for in Jupiter's atmosphere than the GRS. That's a good thing, because for something so famous, it can be surprisingly difficult to see. It appears slightly more distinct when Jupiter is viewed through a light green or blue filter.

Below is a calculator you can use to predict the local and Universal Times and dates when the center of the Great Red Spot should cross Jupiter's central meridian, the imaginary line down the center of the planet's disk from pole to pole. Click "Initialize to today" to view the dates and times of the next three transits of the GRS. Or you can enter any date this year to find other transit times. The listed times should be accurate to within a few minutes.

Please enter a date:
(mm/dd/yyyy)
Universal Times
of Red Spot transits
centered on date:


Corresponding
local dates & times
of Red Spot transits:


Note: local times are based on a time zone offset of
  hour(s) from UT as given by your Web browser.

JupiterMoons iconIf you enjoy using this utility and own an iPhone or iPad, you might be interested in our newest app. JupiterMoons is your essential guide to observing Jupiter whenever the king of planets reigns the night sky, showing you the locations of Io, Europa, Ganymede, Callisto, and the Great Red Spot at any date and time. Available on the iTunes App Store for only $2.99.

These predictions assume the Red Spot was at Jovian System II longitude 333° in June 2020 and continues to drift 1.75° per month, based on historical trends noted by JUPOS. If the GRS moves elsewhere, it will transit 123 minutes late for every 1° of longitude greater than that used in this tool or 123 minutes early for every 1° less than the longitude in this tool. Features on Jupiter appear closer to the central meridian than to the limb — and thus are well placed for viewing — for 50 minutes before and after their transit times. If you see any problems with this tool, or any of our interactive tools, please send an email to help@skyandtelescope.org.

Comments


Image of chuck schlemm

chuck schlemm

June 23, 2014 at 10:29 am

Can you update list of predicted Great Red Spot transits? Current list ended in May 2014. Thank you.

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Monica Young

June 23, 2014 at 2:50 pm

Hi, Chuck, welcome to the site. The latest issue of Sky & Telescope will always have a list of the Great Red Spot transits (with the exception of the July issue, since Jupiter goes into conjunction on July 24th). You can also, of course, simply enter a date into the Javascript tool to find out transit times near that date :).

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vivian-flinspach

August 20, 2014 at 8:57 pm

Hi! I cannot find the August chart showing the positions of Jupiter's moons (egresses, ingresses ,transitions, etc ) that is usually in my monthly Sky and Telescope magazine. Have you stopped putting it in the magazine or did I miss it? Can I get it off your website?
Thank you! Love the magazine! Vivian

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JR

October 20, 2014 at 1:07 pm

Hi, Vivian--A much belated reply, but I hope you are enjoying the charts showing the positions of Jupiter's moons in more recent issues. We generally don't publish the chart in those months that Jupiter isn't readily visible. Jupiter was in conjunction with Sun on July 24th, so its position made for difficult observing well into August.

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SHANKAR PRASAD MITRA

March 13, 2017 at 7:24 am

Can I get the transit point data of 25years before 2000 and 25 years after 2000 ?

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Image of Stub Mandrel

Stub Mandrel

May 14, 2018 at 3:06 pm

Looking at http://jupos.privat.t-online.de/ the rate the spot is moving seems to be closer to 2 degrees a month at the moment and even higher last year, rather than the 1.25 degrees given above.
Your predicted position is close to Calsky's though.
How often is the calculator reset and are you actually using 1.25 degrees or 2 degrees at the moment?

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Stub Mandrel

May 14, 2018 at 3:09 pm

FWIW Calsky appears to be using 2 degrees and the difference between this calculator and Calsky goes from 2 minutes today to 61 minutes on 14 June.

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Image of Monica Young

Monica Young

May 16, 2018 at 1:16 pm

Hmm...We looked into this, but the times we're seeing on Calsky.com for June 14th match the prediction from our code almost exactly (within 6 minutes).

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Monica Young

May 15, 2018 at 3:16 pm

The description was outdated — I have now updated the description to reflect that the code is advancing at a rate of 2 degrees per month. We typically update the javascript code once a year, or more often if it becomes necessary.

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chapmandave

May 21, 2019 at 8:11 am

Hi Monica, it looks like it is time to update the GRS longitude again. By the way, there seems to be a bug in the conversion of UT to Local time, where it can be off by 12 hours.

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chapmandave

May 21, 2019 at 8:13 am

Oops, I did not see the am/pm on the local times. They get cut off in my browser!

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Image of Monica Young

Monica Young

May 22, 2019 at 1:29 pm

Thanks, Dave, the program currently uses a GRS longitude of 317 degrees.

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chapmandave

July 29, 2019 at 7:31 am

Hi Monica. Observations from Nova Scotia last night are consistent with this longitude within a degree or so. Thanks for keeping this up to date. The iOS Jupiter app, however, needs updating. It's predicting GRS transit times about 30 minutes early.

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