It sounds almost like science fiction, but it’s true: Jupiter is shrinking. The largest planet in our solar system hasn’t always been this way. 4.5 billion years ago, it was even twice as large. And it’s still contracting — slowly but steadily.
And that’s not the only thing puzzling astronomers. Its famous Great Red Spot, the giant storm that has been visible for centuries, is suddenly behaving… differently. As if it’s breathing. As if it’s alive.
Why Jupiter is Shrinking: Back to the Beginning
Jupiter is a gas giant. Unlike planets like Earth, it has no solid surface. When it first formed, it was extremely hot — and therefore inflated. The young Jupiter was twice as large as it is now. Its enormous mass of gas was still in full motion.
Over the centuries, it has slowly cooled down. And with this cooling, Jupiter continues to shrink. Its volume decreases, but its mass remains the same — it’s becoming more compact. This process takes place over billions of years but is still ongoing.
Jupiter’s Role in our Solar System
Jupiter isn’t just a large planet — it plays a leading role in the solar system. Its enormous mass causes it to attract or push away other objects. This makes it function as a kind of cosmic shield: many comets and asteroids that might otherwise travel toward the inner planets are deflected or swallowed by Jupiter.
Additionally, it subtly influences the orbits of other planets with its gravity. Scientists also think that Jupiter’s presence in the early history of the solar system was crucial for the distribution of matter. Without Jupiter, Earth — and life on it — might never have existed.
The Great Red Spot: a Storm That’s Behaving Strangely
As Jupiter shrinks, its most recognizable feature is also changing: the Great Red Spot. This colossal storm has been visible for over 150 years, but recent observations from the Hubble Space Telescope show something remarkable.
The storm is not only shrinking in size, it’s also moving in an unusual way. Hubble observed that the spot expands and contracts — as if it’s being squeezed. Every 90 days, the shape changes, like a stress ball that swells up and then contracts again.
And all this while Jupiter itself is also shrinking. Coincidence? Or is there a connection?
What Causes Jupiter’s Shrinkage?
There are two main reasons why Jupiter is shrinking:
- Natural cooling
Jupiter radiates more heat than it receives from the sun. As it cools, its gas mass sinks. This makes its diameter smaller — and this process has been ongoing for billions of years. - Internal contraction
Enormous processes take place beneath the gas surface. Gas layers are compressed by gravity and pressure. These forces cause Jupiter to shrink, even though it’s barely noticeable within a human lifetime.
And What about that Wobbling Storm?
The Great Red Spot is influenced by powerful jet streams. These streams rage along both sides of the storm, as if it’s trapped between two walls of air. This probably causes the “squeeze effect”.
But there’s something strange going on: when the storm slows down, it gets bigger. When it speeds up, it gets smaller. This contradictory movement has completely surprised scientists. And it’s happening simultaneously with Jupiter’s gradual shrinkage.
Why Jupiter’s Shrinking Matters
The fact that Jupiter is shrinking isn’t just a tidbit for space enthusiasts. It tells us something fundamental about how gas giants work — not just in our solar system, but also with exoplanets in other star systems.
- How long can storms persist without solid ground?
- What role do jet streams play in forming stable weather systems?
- And how does a planet physically change over time?
All questions we can ask thanks to research into Jupiter’s shrinkage and the dynamics of its atmosphere.
What Can You See Yourself?
The Great Red Spot is visible with a telescope, though you’ll need some magnification. Note: telescope systems with a short focal length, like the Seestar, are not suitable for this. For planetary details, you need a classical telescope with more magnification, such as a Celestron 114AZ or a Dobson 130/650.
Conclusion: Jupiter is Shrinking and We’re Learning More
We now know for certain that Jupiter is shrinking. That its famous storm suddenly wobbles up and down? We don’t have a definitive answer for that yet. But each measurement brings us closer to understanding the core of this mysterious gas giant.
Next step: the James Webb Space Telescope. It will study the spot in infrared to see what’s happening deeper inside the storm.
