<p>Yes, as with all other storms, the Great Red Spot is dynamic, so it constantly changes its size and shape and it shifts and drifts and is not just &quot;locked in a definite position&quot;. According to <a href="https://www.nasa.gov/feature/goddard/2018/jupiters-great-red-spot-getting-taller-as-it-shrinks" rel="noreferrer">nasa.gov</a>:</p>
<blockquote>
<p><strong>The new findings indicate that the Great Red Spot recently started to drift westward faster than before</strong>. The storm always stays at the same latitude, held there by jet streams to the north and south, but it circles the globe in the opposite direction relative to the planet’s eastward rotation. Historically, it’s been assumed that this drift is more or less constant, but in recent observations, the team found the spot is zooming along much faster.</p>
</blockquote>
<p>If we take real numbers then according to <a href="http://jupos.privat.t-online.de/" rel="noreferrer">JUPOS</a>, it is predicted that the Red Spot (which was at Jovian System II longitude 2° in July 2021) will continue to drift 1.75° per month (<a href="https://skyandtelescope.org/observing/interactive-sky-watching-tools/transit-times-of-jupiters-great-red-spot/" rel="noreferrer">source</a>).</p>
<p>For more information, see my answer <a href="https://astronomy.stackexchange.com/questions/35622/why-is-the-great-red-spot-shrinking/39485#39485">here</a>.</p>

CC BY-SA 4.0
2021-12-04T07:29:20.480Z
i love JUPOS !! i'm going to add an additional JUPOS answer.
giardia
CC BY-SA 4.0
2021-07-30T08:13:23.240Z
2021-07-31T16:58:52.150Z
2021-07-31T16:58:52.150Z
Nilay Ghosh
<p>It does drift relative to other parts of the atmosphere. The lack of a surface makes defining the actual rotation period of Jupiter rather difficult. The currently accepted value of 9h:55m:29.7s is based on the average rotation of the interior, inferred from magnetic field measurements.</p>
<p>The Red Spot was previously used to define the rotation period, averaging at 9h:55m:42s. With no surface features to break up the winds, this period is quite stable.</p>
<p>In the longer term the drift speed does vary. The spot has &quot;lapped&quot; the planet at least 10 times since the early nineteenth century. Its drift rate has changed dramatically over the years and has been linked to the brightness of the South Equatorial Belt and the presence or absence of a South Tropical Disturbance.</p>
<p>The timelapse by Voyager shows the relative movement in different bands.</p>
<p><a href="https://upload.wikimedia.org/wikipedia/commons/a/a3/790106-0203_Voyager_58M_to_31M_reduced.gif" rel="nofollow noreferrer"><img src="https://upload.wikimedia.org/wikipedia/commons/a/a3/790106-0203_Voyager_58M_to_31M_reduced.gif" alt="(Jupiter rotation animation)" /></a></p>

CC BY-SA 4.0
2021-07-30T14:28:02.247Z
When you say "lapped", that implies that for long periods of time, it would not be visible from any Earthbound (including Earth-orbiting) telescope, due to being on the far side of the planet?  I'm not sure if I've seen many pictures of Jupiter without the Spot.  Is it just because the last time it was not visible from Earth predates the technology to view and photograph it?
Darrel Hoffman
CC BY-SA 4.0
2021-07-30T14:35:14.200Z
@DarrelHoffman Jupiter itself rotates every 10 hours, so the red spot is not always visible from Earth.  But if you are going to publish a picture of Jupiter, would you pick one that didn't show its most prominent and popular feature?
Michael Richardson
CC BY-SA 4.0
2021-07-30T14:39:14.180Z
@MichaelRichardson Sorry, right, I'm just having trouble understanding how we decide it's "lapped" the planet, when there aren't any fixed points to measure its rotation by.
Darrel Hoffman
CC BY-SA 4.0
2021-07-30T15:35:25.413Z
Nice video. I can see different roation velocities. How is one rotation defined? There is no solid core (or is there?). How is the total angular momentum determined?
Deschele Schilder
CC BY-SA 4.0
2021-07-30T16:42:55.080Z
Satellites measure the rotation speed of the magnetosphere, this is linked to the conductive interior of Jupiter and can be considered to be the rotation of the planet's interior. https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2009GL040094
James K
CC BY-SA 4.0
2021-07-31T13:30:59.493Z
Perhaps add a little bit more information about the timelapse? E.g., is it from pictures taken 9 hour 55 minutes apart?
Peter Mortensen
CC BY-SA 4.0
2021-08-01T17:36:37.240Z
@DarrelHoffman You've not seen any Jupiter photos without the red spot, because most likely all the photos of Jupiter you've seen have come from sources like news stories, or museum displays, or even textbooks in segments not actually specifically about studying Jupiter's weather, and people who put together such works don't use pictures of the non-red-spot side of Jupiter, because they want people to be able to recognize it as Jupiter, and the red spot is how most of the human population does that.
Matthew Najmon
CC BY-SA 4.0
2021-08-02T16:27:13.167Z
beautiful timelapse! I can't stop looking at it
Prallax
CC BY-SA 4.0
2021-12-04T07:26:35.067Z
@james k, my reputation is too weak to edit... can  you change "inferred from satellite measurements" to "inferred from magnetic field measurements"? and also update the rotation period to 9h:55m:29.7s.

https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/GL004i002p00065
giardia
CC BY-SA 4.0
2021-12-04T08:15:24.707Z
That paper is from 1977,  got anything newer?
James K
CC BY-SA 4.0
2021-12-06T18:11:31.413Z
@james k, yes, that paper was just the primary reference for the currently-used system III (interior) rotation rate.

the same number comes from the the 870.5360000 deg/day rotation rate give in the current IAU standard, archinal++2018: https://doi.org/10.1007/s10569-017-9805-5 . actually, i just noticed i have gained edit privileges, so i am just going to update the rotation rate in your nice answer that i already upvoted.
giardia
CC BY-SA 4.0
2021-07-30T07:10:44.933Z
2021-12-07T14:00:02.057Z
2021-12-07T14:00:02.057Z
James K
<p>There is a great answer to this on the <a href="http://jupos.org" rel="nofollow noreferrer">http://jupos.org</a> site. The updated graph is at the link <a href="https://jupos.privat.t-online.de/img/Grs.GIF" rel="nofollow noreferrer">https://jupos.privat.t-online.de/img/Grs.GIF</a>, but it is a vintage site so browsers may have some issues with security certificates. Here is the version currently available in dec. 2021:</p>
<p><a href="https://i.sstatic.net/JBs1W.gif" rel="nofollow noreferrer"><img src="https://i.sstatic.net/JBs1W.gif" alt="plot of GRS longitude vs. time" /></a></p>
<p>To understand the plot, it's helpful to know that time is increasing downwards, and the x-axis is the great red spot (GRS) location in system II longitude. It's shown as a huge collection of points, each one measured on an image taken by an amateur astronomer.</p>
<p>System II was defined as the average rotation rate of the GRS, so if the spot didn't move around, all the dots would be arranged in a straight vertical line. Instead, you can see wiggles (in particular a 90-day oscillation), and an overall slope. The slope means that the GRS drift rate has changed in the years following the creation of the system II longitude system.</p>

CC BY-SA 4.0
2021-12-07T14:28:47.103Z
Interesting! Do you know why is there a gap in early 2021?
Jean-Marie Prival
CC BY-SA 4.0
2021-12-07T15:21:18.693Z
@Jean-MariePrival Jupiter was behind the Sun as seen from Earth. Closest approach was on January 29th at approximately 0.5° angular distance.
Karsten Kretschmer
CC BY-SA 4.0
2021-12-07T15:52:33.567Z
@KarstenKretschmer Makes sense, thanks!
Jean-Marie Prival
CC BY-SA 4.0
2021-12-04T07:40:49.553Z
2021-12-07T14:28:09.737Z
2021-12-07T14:28:09.737Z
giardia
<p>A person could be forgiven when looking at Jupiter's Red Spot storm for concluding that it doesn't <em>move.</em> That it's geologically locked in place. But is it?</p>
<p>I know it's a stretch to use the phrase &quot;geologically locked in place&quot; when referring to a gas giant. So let me ask the question in a little different way.</p>
<p>As we observe Jupiter's rotation, does the storm show up <em>in the very same spot</em> on each rotation or does the spot move around, sometimes appearing more quickly on one rotation and later on the next? I suspect that the Red Spot can't move <em>latitudinaly</em> as it's likely bound to the band of turbulence it's in. But can it move &quot;longitudinally&quot; within that band or does it literally stay in one place, facing the Sun every 9 hours and 50 minutes (assuming it's equatorial, you get my point) like clockwork?</p>

CC BY-SA 4.0
2021-07-30T15:39:28.153Z
Looks the face of Jupiter always the same seen from Earth?
Deschele Schilder
CC BY-SA 4.0
2021-07-30T20:48:13.923Z
As Jupiter is not solid (in the way that earth is), I’m not sure there is such a thing as “geological position”.
RBarryYoung
CC BY-SA 4.0
2021-07-30T22:13:25.243Z
@RBarryYoung, Jupiter may or may not have a solid core, but the magnetic field (and thus, presumably, the core) does have a well-defined period of rotation.
Mark
CC BY-SA 4.0
2021-08-02T00:36:03.717Z
Linguistic nitpick: since ‘[geology](https://en.wiktionary.org/wiki/geology)’ is specifically about the study of Earth, wouldn't the study of Jupiter's composition be called something else (possibly with ‘[Jove](https://en.wiktionary.org/wiki/Jove#English)-’ as the root)?
gidds
<jupiter><weather><great-red-spot><cyclones>
Is Jupiter's Red Spot "locked in place" or does it move around?
JBH
# Is Jupiter's Red Spot "locked in place" or does it move around?

(Asked by: username_0 on 2021-07-30)

A person could be forgiven when looking at Jupiter's Red Spot storm for concluding that it doesn't *move.* That it's geologically locked in place. But is it?

I know it's a stretch to use the phrase "geologically locked in place" when referring to a gas giant. So let me ask the question in a little different way.

As we observe Jupiter's rotation, does the storm show up *in the very same spot* on each rotation or does the spot move around, sometimes appearing more quickly on one rotation and later on the next? I suspect that the Red Spot can't move *latitudinaly* as it's likely bound to the band of turbulence it's in. But can it move "longitudinally" within that band or does it literally stay in one place, facing the Sun every 9 hours and 50 minutes (assuming it's equatorial, you get my point) like clockwork?

**Tags:** jupiter, weather, great-red-spot, cyclones
> **Comments:**
> **username_1**: Looks the face of Jupiter always the same seen from Earth?  
> **username_2**: As Jupiter is not solid (in the way that earth is), I’m not sure there is such a thing as “geological position”.  
> **username_3**: @RBarryYoung, Jupiter may or may not have a solid core, but the magnetic field (and thus, presumably, the core) does have a well-defined period of rotation.  
> **username_4**: Linguistic nitpick: since ‘[geology](https://en.wiktionary.org/wiki/geology)’ is specifically about the study of Earth, wouldn't the study of Jupiter's composition be called something else (possibly with ‘[Jove](https://en.wiktionary.org/wiki/Jove#English)-’ as the root)?  

---

## 3 answers

### Answer by username_7 on 2021-07-30. Score: 36

It does drift relative to other parts of the atmosphere. The lack of a surface makes defining the actual rotation period of Jupiter rather difficult. The currently accepted value of 9h:55m:29.7s is based on the average rotation of the interior, inferred from magnetic field measurements.

The Red Spot was previously used to define the rotation period, averaging at 9h:55m:42s. With no surface features to break up the winds, this period is quite stable.

In the longer term the drift speed does vary. The spot has "lapped" the planet at least 10 times since the early nineteenth century. Its drift rate has changed dramatically over the years and has been linked to the brightness of the South Equatorial Belt and the presence or absence of a South Tropical Disturbance.

The timelapse by Voyager shows the relative movement in different bands.

[![(Jupiter rotation animation)](https://upload.wikimedia.org/wikipedia/commons/a/a3/790106-0203_Voyager_58M_to_31M_reduced.gif)](https://upload.wikimedia.org/wikipedia/commons/a/a3/790106-0203_Voyager_58M_to_31M_reduced.gif)

> **Comments:**
> **username_8**: When you say "lapped", that implies that for long periods of time, it would not be visible from any Earthbound (including Earth-orbiting) telescope, due to being on the far side of the planet?  I'm not sure if I've seen many pictures of Jupiter without the Spot.  Is it just because the last time it was not visible from Earth predates the technology to view and photograph it?  
> **username_9**: @DarrelHoffman Jupiter itself rotates every 10 hours, so the red spot is not always visible from Earth.  But if you are going to publish a picture of Jupiter, would you pick one that didn't show its most prominent and popular feature?  
> **username_8**: @MichaelRichardson Sorry, right, I'm just having trouble understanding how we decide it's "lapped" the planet, when there aren't any fixed points to measure its rotation by.  
> **username_1**: Nice video. I can see different roation velocities. How is one rotation defined? There is no solid core (or is there?). How is the total angular momentum determined?  
> **username_7**: Satellites measure the rotation speed of the magnetosphere, this is linked to the conductive interior of Jupiter and can be considered to be the rotation of the planet's interior. https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2009GL040094  
> **username_10**: Perhaps add a little bit more information about the timelapse? E.g., is it from pictures taken 9 hour 55 minutes apart?  
> **username_11**: @DarrelHoffman You've not seen any Jupiter photos without the red spot, because most likely all the photos of Jupiter you've seen have come from sources like news stories, or museum displays, or even textbooks in segments not actually specifically about studying Jupiter's weather, and people who put together such works don't use pictures of the non-red-spot side of Jupiter, because they want people to be able to recognize it as Jupiter, and the red spot is how most of the human population does that.  
> **username_12**: beautiful timelapse! I can't stop looking at it  
> **username_6**: @james k, my reputation is too weak to edit... can  you change "inferred from satellite measurements" to "inferred from magnetic field measurements"? and also update the rotation period to 9h:55m:29.7s.  https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/GL004i002p00065  
> **username_7**: That paper is from 1977,  got anything newer?  
> **username_6**: @james k, yes, that paper was just the primary reference for the currently-used system III (interior) rotation rate.  the same number comes from the the 870.5360000 deg/day rotation rate give in the current IAU standard, archinal++2018: https://doi.org/10.1007/s10569-017-9805-5 . actually, i just noticed i have gained edit privileges, so i am just going to update the rotation rate in your nice answer that i already upvoted.  

---

### Answer by username_5 on 2021-07-30. Score: 20

Yes, as with all other storms, the Great Red Spot is dynamic, so it constantly changes its size and shape and it shifts and drifts and is not just "locked in a definite position". According to [nasa.gov](https://www.nasa.gov/feature/goddard/2018/jupiters-great-red-spot-getting-taller-as-it-shrinks):

> **The new findings indicate that the Great Red Spot recently started to drift westward faster than before**. The storm always stays at the same latitude, held there by jet streams to the north and south, but it circles the globe in the opposite direction relative to the planet’s eastward rotation. Historically, it’s been assumed that this drift is more or less constant, but in recent observations, the team found the spot is zooming along much faster.

If we take real numbers then according to [JUPOS](http://jupos.privat.t-online.de/), it is predicted that the Red Spot (which was at Jovian System II longitude 2° in July 2021) will continue to drift 1.75° per month ([source](https://skyandtelescope.org/observing/interactive-sky-watching-tools/transit-times-of-jupiters-great-red-spot/)).

For more information, see my answer [here](https://astronomy.stackexchange.com/questions/35622/why-is-the-great-red-spot-shrinking/39485#39485).

> **Comments:**
> **username_6**: i love JUPOS !! i'm going to add an additional JUPOS answer.  

---

### Answer by username_6 on 2021-12-04. Score: 2

There is a great answer to this on the <http://jupos.org> site. The updated graph is at the link <https://jupos.privat.t-online.de/img/Grs.GIF>, but it is a vintage site so browsers may have some issues with security certificates. Here is the version currently available in dec. 2021:

[![plot of GRS longitude vs. time](https://i.sstatic.net/JBs1W.gif)](https://i.sstatic.net/JBs1W.gif)

To understand the plot, it's helpful to know that time is increasing downwards, and the x-axis is the great red spot (GRS) location in system II longitude. It's shown as a huge collection of points, each one measured on an image taken by an amateur astronomer.

System II was defined as the average rotation rate of the GRS, so if the spot didn't move around, all the dots would be arranged in a straight vertical line. Instead, you can see wiggles (in particular a 90-day oscillation), and an overall slope. The slope means that the GRS drift rate has changed in the years following the creation of the system II longitude system.

> **Comments:**
> **username_13**: Interesting! Do you know why is there a gap in early 2021?  
> **username_14**: @Jean-MariePrival Jupiter was behind the Sun as seen from Earth. Closest approach was on January 29th at approximately 0.5° angular distance.  
> **username_13**: @KarstenKretschmer Makes sense, thanks!  

---

