Scroll down to read this post.


Please consider supporting my work, as I take no advertisements nor accept any sponsors in order to keep the website clean, easy to read, and to avoid any accusations of conflict of interest. Your support leaves me entirely independent, able to say whatever I think while being free from censorship or reprisals.


You can support me either by giving a one-time contribution or a regular subscription. There are five ways of doing so:


1. Zelle: This is the only internet method that charges no fees. All you have to do is use the Zelle link at your internet bank and give my name and email address (zimmerman at nasw dot org). What you donate is what I get.


2. Patreon: Go to my website there and pick one of five monthly subscription amounts, or by making a one-time donation.

3. A Paypal Donation:

4. A Paypal subscription:

5. Donate by check, payable to Robert Zimmerman and mailed to
Behind The Black
c/o Robert Zimmerman
P.O.Box 1262
Cortaro, AZ 85652

Jupiter’s Great Red Spot continues to shrink, possibly to its smallest size ever measured

Jupiter, as seen by Hubble in 2020
A 2020 Hubble picture of Jupiter.
Click for full image.

Long term data from numerous observatories shows that the Great Red Spot on Jupiter, the largest and longest lasting storm in the solar system, has been continuously shrinking for decades, and appears approaching this year its smallest size ever measured.

Despite so many factors working to keep it “alive” the Spot may be in need of life support. It’s been shrinking for decades. In 2012 the rate of shrinkage abruptly accelerated, something many amateur observers have commented on since that time. Several years later, while still shrinking in diameter, it expanded in latitude becoming more circular. Now it’s narrowed again and continues to diminish in both axes. This observing season I’ve been struck by the Spot’s unusually small size. That, along with its pale pink color and turbulent environment, have made it less obvious than ever.

…Using the WinJUPOS program and one of his recent high-resolution images, Peach measured the Great Red Spot’s diameter on November 6, 2023, at 12,500 kilometers or about 7,770 miles across. If confirmed it would make this season’s GRS not only smaller than the Earth (12,756 kilometers or 7,926 miles across) but the smallest size in observational history. A British Astronomical Association Jupiter section bulletin on October 30th described it as “the smallest it has ever been.” That’s a far cry from the late 1800s when the Spot ballooned to 41,000 kilometers (25,500 miles) — big enough to swallow three Earths with room to spare. Now it can barely contain one!

No one knows if this shrinkage is merely a normal long term fluctuation, or a sign that this many-centuries-old storm is finally dissippating. When it comes to the solar system’s gas giants, their size and long orbits make any firm conclusion difficult in only a few centuries of observation. To understand them properly will likely require thousands of years of observations, covering many orbits and seasons.

Genesis cover

On Christmas Eve 1968 three Americans became the first humans to visit another world. What they did to celebrate was unexpected and profound, and will be remembered throughout all human history. Genesis: the Story of Apollo 8, Robert Zimmerman's classic history of humanity's first journey to another world, tells that story, and it is now available as both an ebook and an audiobook, both with a foreword by Valerie Anders and a new introduction by Robert Zimmerman.

The ebook is available everywhere for $5.99 (before discount) at amazon, or direct from my ebook publisher, ebookit. If you buy it from ebookit you don't support the big tech companies and the author gets a bigger cut much sooner.

The audiobook is also available at all these vendors, and is also free with a 30-day trial membership to Audible.

"Not simply about one mission, [Genesis] is also the history of America's quest for the moon... Zimmerman has done a masterful job of tying disparate events together into a solid account of one of America's greatest human triumphs."--San Antonio Express-News


  • Col Beausabre

    Climate change! Guess the Jovians will have to drive EV’s and get their power from “renewables”

  • John

    I just hope black monoliths don’t show up and shrink the whole planet.

  • wayne

    ya’ beat me to it…

    2010: The Year We Make Contact (1984)
    “It’s Shrinking”

  • Looks like several of us saw that movie …

  • wayne

    “Something wonderful” was supposed to happen in that movie, but I was not entirely pleased.

    Outland (1981)
    Intro scene….

  • pzatchok

    Other than aliens I have always wondered what started the spot and what keeps it going.

    Could it be some solid ground anomaly like a mountain or is it just a curious wind phenomenon?
    Could it have been started by a planet sized or larger body falling into it?

  • Alex Andrite

    “Knock Knock”
    “who is there?”
    “… er ah … a friend … of Jupiter ….”

    “No way Shrinking Red, you cannot fool me again…… ”

    ” … oh uh ….. please, just for awhile …?”

    “There is NO ROOM for you in here. Already too many rocks, chunks, and those other scary things … ”

    “…. ( long dramitic sigh ) …… sigh” ” … this is very painful for me you know….”

    “Nope,… emotional manipulations will not do it …… NO ROOM”.
    “Lose weight or ….. ”

    ” ok ok ok ….. just give me a few cycles …. this is so embarassing ………
    now what to abstain from..? Not the wind certainly…… oh oh oh ….
    not my chromium and iron …… whew ….
    gotta think this one through …..


    “No hurry for now …..
    they are watching, and lose attention easily…”

Readers: the rules for commenting!


No registration is required. I welcome all opinions, even those that strongly criticize my commentary.


However, name-calling and obscenities will not be tolerated. First time offenders who are new to the site will be warned. Second time offenders or first time offenders who have been here awhile will be suspended for a week. After that, I will ban you. Period.


Note also that first time commenters as well as any comment with more than one link will be placed in moderation for my approval. Be patient, I will get to it.

Leave a Reply

Your email address will not be published. Required fields are marked *