What If? Lab
What if you could walk on Jupiter’s cloud tops?
Jupiter is a giant planet made of gas. What if you could stand on its clouds? Let's imagine a visit with Olly!
Jupiter is so big that about 1,000 Earths could fit inside it, but it has no solid ground at all. Imagine standing on a platform at its cloud tops: you would feel more than twice as heavy, and you could watch a storm twice as wide as Earth.
Jupiter is a hydrogen-helium gas giant with no true surface. At the 1-bar level that defines its 'cloud tops', NASA gives a mean gravity of 25.92 m/s², a temperature of −108 °C and winds up to about 150 m/s. This thought experiment imagines a platform there.
The big question
Jupiter is the biggest planet. It is made mostly of gas.
What if you could stand on top of its clouds? What would you feel and see?
Jupiter is a giant. It is 11 times wider than Earth, and if it were hollow, about 1,000 Earths could fit inside. Its colorful stripes are bands of clouds, swirling and racing around the planet.
So what if you could stand on top of those clouds? This is a thought experiment: people cannot go to Jupiter. But spacecraft have taught scientists enough to imagine what such a visit would be like. Choose a path and find out.
Jupiter's mean radius is 69,911 km, about 11 times Earth's, and its mass is about 318 Earth masses. Like the Sun, it is made mostly of hydrogen and helium.
This thought experiment imagines an observer on a platform at the 1-bar pressure level, the level conventionally used for Jupiter's radius and gravity. Each step separates measured facts from ideas about what the visit would feel like.
Explore the idea
Make a prediction
What would you stand on at Jupiter's cloud tops?
If you arrived at Jupiter's cloud tops, what would be under your feet?
What lies beneath Jupiter's 1-bar cloud level?
- Solid rock
- No ground: gases and liquids
- A sheet of ice
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Established fact
Jupiter is the biggest planet.
Jupiter is the largest planet. It has more than twice as much material as everything else in the solar system except the Sun put together.
Jupiter holds more than twice the combined mass of the other bodies in the solar system (NASA).
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An idea scientists discuss
Our visit is pretend. People cannot go to Jupiter.
Walking on Jupiter's clouds is a thought experiment: no person could go there, so how it would feel is an idea built from measurements.
The visit is hypothetical; the sensations described are reasoned from measured gravity, temperature and winds.
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Established fact
Jupiter has no ground to stand on.
Jupiter is a gas giant with no true surface. It is mostly swirling gases and liquids.
As a gas giant, Jupiter lacks a true surface; a spacecraft would have nowhere to land (NASA).
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Established fact
Jupiter is huge. About 1,000 Earths could fit inside it.
Jupiter is 11 times wider than Earth. If it were hollow, about 1,000 Earths could fit inside.
Jupiter's radius is 69,911 km, about 11 times Earth's; as a hollow shell it could hold about 1,000 Earths (NASA).
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An idea scientists discuss
A floating platform is pretend. People cannot really go there.
Our platform is imaginary. No person can visit Jupiter, so this whole trip is a thought experiment.
The platform is a device for the thought experiment; no known structure could stay in place in Jupiter's atmosphere, and NASA notes that spacecraft flying deeper in are destroyed by its pressures and temperatures.
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Established fact
Jupiter pulls more than twice as hard as Earth.
At Jupiter's cloud tops, gravity is about two and a half times as strong as on Earth.
Jupiter's mean gravity at the 1-bar level is 25.92 m/s², against 9.82 m/s² for Earth (NASA).
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Established fact
The pull is a bit different in different places on Jupiter.
Jupiter's pull at the cloud tops is a bit weaker at its equator and stronger at its poles.
Effective acceleration at 1 bar is 23.12 m/s² at the equator and 27.01 m/s² at the poles (NASA).
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An idea scientists discuss
Standing up might feel like carrying a friend your size on your back, and then some.
Feeling more than twice your weight might make standing and walking very tiring, a bit like carrying more than one friend your size on your back.
The physiological effect of sustained gravity at about 2.5 times Earth's is not something this lab can quantify.
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Established fact
Jupiter's Great Red Spot is a storm wider than Earth.
The Great Red Spot is a swirling oval of clouds twice as wide as Earth, seen on Jupiter for more than 300 years.
The Great Red Spot, twice Earth's width, has been observed for more than 300 years (NASA).
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Established fact
Jupiter's winds are very fast.
Some of Jupiter's winds reach up to 539 kilometers per hour at the equator.
Over a dozen prevailing winds sweep Jupiter, some reaching 539 km/h at the equator (NASA).
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An idea scientists discuss
The storm would look giant from the platform.
Seen from the cloud tops, a storm wider than our whole planet would fill a huge part of the view. Exactly how it would look up close is something we can only imagine.
Its appearance from within the cloud deck is imagined; real images come from spacecraft looking down from above.
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Established fact
A robot spacecraft called Juno studies Jupiter.
NASA's Juno spacecraft measures Jupiter's gravity and magnetic field from orbit.
Juno's measurements indicate a core that is partially dissolved, with no clear separation from the surrounding metallic hydrogen (NASA).
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Established fact
Scientists think Jupiter is too wild for living things.
NASA says Jupiter's conditions are most likely too extreme and changeable for living things to adapt to.
NASA judges Jupiter's environment most likely too extreme and volatile for organisms to adapt to.
Standing on Earth
On Earth, you stand on solid ground. The ground holds you up.
Earth's pull keeps your feet down. The air around you is just right to breathe.
On Earth, the ground under your feet is solid rock and soil. Earth's gravity pulls you down onto it, and that pull is what you feel as your weight.
Earth's gravity at the surface is about 9.8 meters per second squared. A day lasts 24 hours, and the air around you is a mixture you can breathe. Every one of those things would be different at Jupiter.
Earth is a rocky planet with a solid surface, a mean gravity of about 9.82 m/s² at the surface and a solar day of 24.0 hours (NASA).
Jupiter differs in every respect that matters for a visitor: it has no solid surface, its pull at the 1-bar level is about two and a half times stronger, its day lasts only 9.9 hours, and its atmosphere is mostly hydrogen and helium.
At Jupiter's cloud tops
Jupiter has no ground. Only clouds and gas, all the way down.
So in our pretend visit, Olly brings a floating platform to stand on!
The first surprise: there's nothing to stand on. NASA explains that Jupiter has no true surface. It is mostly swirling gases and liquids, so a spacecraft would have nowhere to land. That's why our visitor needs an imaginary platform.
Standing there, you'd feel more than twice as heavy as on Earth. The clouds around you would be cold clouds of ammonia and water, racing past in strong winds. It would be very cold too: about −108 degrees Celsius.
Jupiter has no true surface: it is mostly swirling gases and liquids, and NASA notes that the extreme pressures and temperatures deeper inside would destroy any spacecraft. The 1-bar level is a reference, not a floor.
There, NASA's Jupiter fact sheet gives a temperature of 165 K (−108 °C), an atmospheric density of 0.16 kg/m³ and winds up to about 150 m/s at low latitudes. NASA describes three likely cloud layers spanning about 71 km: the top probably ammonia ice, then ammonium hydrosulfide crystals, then perhaps water ice and vapor.
Why it is so different
Jupiter is huge and very heavy. That makes its pull strong.
It spins fast, too. That helps make its winds and storms.
Jupiter is so massive that its gravity is much stronger than Earth's. At its cloud tops, the pull is about two and a half times as strong, so everything would weigh more than twice as much.
Jupiter also spins very fast: a day there lasts only about 10 hours. NASA explains that this fast spin creates strong jet streams that stretch the clouds into dark belts and bright zones. With no solid ground to slow them, its storms can last for many years.
Mean gravity at the 1-bar level is 25.92 m/s², 2.64 times Earth's. The effective acceleration at the 1-bar level is 23.12 m/s² at the equator and 27.01 m/s² at the poles, according to the same NASA fact sheet.
NASA attributes Jupiter's banded appearance to jet streams driven by that fast rotation, and notes that with no solid surface to slow them, its spots can persist for many years. These are the conditions our imaginary visitor would meet.
Visiting Jupiter for real
People cannot visit Jupiter. But robot spacecraft can fly around it.
They send back pictures and measurements. That is how we know so much!
No person can visit Jupiter, and no spacecraft can land there. Instead, robot spacecraft fly around it. NASA's Juno spacecraft measures Jupiter's gravity and magnetic field from orbit, and its data suggest that Jupiter's core is not a solid ball but is partly dissolved, or 'fuzzy'.
So the cloud-top walk stays a thought experiment. Scientists still learn a great deal by watching Jupiter's clouds, storms and pull from a safe distance.
NASA's Juno spacecraft, measuring Jupiter's gravity and magnetic field, found data suggesting the core is much larger than expected and not solid: partially dissolved, with no clear boundary with the surrounding metallic hydrogen, a 'dilute' or 'fuzzy' core.
NASA's assessment is that Jupiter's environment is most likely too extreme and volatile for organisms to adapt to. A walk on its clouds is therefore a way to think about gravity, weather and planetary structure, not a possible journey.
Amazing facts
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Jupiter has the shortest day of all the planets.
Jupiter has the shortest day in the solar system: it spins once in about 10 hours.
NASA lists Jupiter's day as 9.9 hours, the shortest of any planet.
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If Earth were a grape, Jupiter would be a basketball.
NASA says that if Earth were the size of a grape, Jupiter would be about as big as a basketball.
Jupiter's mean radius, 69,911 km, is about 11 times Earth's (NASA).
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Jupiter's big red storm is older than any person alive.
The Great Red Spot has been seen on Jupiter for more than 300 years.
The Great Red Spot has been observed for more than three centuries (NASA).
Words to know
- gas giant
- a huge planet made mostly of gases, with no solid surface
- gravity
- the pull that a planet has on everything near it
- weight
- how hard gravity pulls on you; it would be more than double on Jupiter
- storm
- a swirl of strong winds and clouds
- spacecraft
- a robot or vehicle built to travel in space
Discovery challenge
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What is under Jupiter's clouds?
What would be under your feet at Jupiter's cloud tops?
What lies beneath Jupiter's 1-bar level?
- Solid rock
- No ground: gases and liquids
- Grass
Show the answer
No ground: gases and liquids
No ground at all, just gas and clouds.
No ground: Jupiter is mostly swirling gases and liquids.
Gases grading into liquids; Jupiter has no true surface.
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On Jupiter's clouds, how heavy would you feel?
On a platform at Jupiter's cloud tops, how heavy would you feel compared with on Earth?
At the 1-bar level, how does your weight compare with your weight on Earth?
- Lighter
- About the same
- More than twice as heavy
Show the answer
More than twice as heavy
More than twice as heavy!
More than twice as heavy: Jupiter's pull there is about 2.5 times Earth's.
About 2.4 to 2.7 times heavier, depending on latitude.
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How wide is Jupiter's Great Red Spot?
How wide is Jupiter's Great Red Spot?
What is the width of the Great Red Spot, according to NASA?
- As wide as a city
- Twice as wide as Earth
- As wide as the Moon
Show the answer
Twice as wide as Earth
Twice as wide as Earth!
It is an oval of clouds twice as wide as Earth.
About twice Earth's width.
Experiments to try
- Watch Try it What If? Lab What if you could stand on Saturn? You could not really stand on Saturn: it is a ball of gas and liquid with no solid surface. But imagine floating at its cloud tops. Saturn has 95 times Earth's mass, yet in our model you would weigh only about 14 percent more than at home, because Saturn is so wide that its cloud tops are very far from its center.
- Watch Try it What If? Lab What if gravity doubled? Gravity makes a dropped ball speed up as it falls. Make the pull twice as strong in our model and the ball speeds up twice as fast, so it lands sooner and hits the ground harder. But it does not land in half the time. Find out why.
- Watch What If? Lab What if an asteroid struck the Moon? The Moon's craters are a record of space rocks landing over billions of years, and small ones still land there every day. Scientists watch for tiny flashes of light on the Moon and later find the brand-new craters. Explore what happens when a rock hits the Moon, and why the Moon keeps going around Earth as always.
- Watch What If? Lab What if a day lasted 48 hours? Earth spins once about every 24 hours, and almost every living thing has a body clock tuned to that day. Imagine a day twice as long: long, bright days and long, dark nights. What would happen to your sleep, to plants and to animals?
- Watch What If? Lab What if Earth were the only planet? Imagine a solar system with just the Sun, Earth and our Moon. The bright 'wandering stars' would vanish from our night sky, the paths of asteroids and comets would change, and scientists would lose the other worlds that teach us how planets work. Explore what Earth would miss.
- Watch What If? Lab What if you visited an icy moon? Jupiter's moon Europa and Saturn's moon Enceladus are covered in ice, but scientists think salty oceans lie underneath. The squeezing pull of their giant planets keeps the insides warm. Imagine walking on the ice, peeking at the ocean below and joining the search for places where life could exist.
Explore next
- Watch Try it What If? Lab What if you could stand on Saturn? You could not really stand on Saturn: it is a ball of gas and liquid with no solid surface. But imagine floating at its cloud tops. Saturn has 95 times Earth's mass, yet in our model you would weigh only about 14 percent more than at home, because Saturn is so wide that its cloud tops are very far from its center.
- Watch Try it What If? Lab What if gravity doubled? Gravity makes a dropped ball speed up as it falls. Make the pull twice as strong in our model and the ball speeds up twice as fast, so it lands sooner and hits the ground harder. But it does not land in half the time. Find out why.
- Watch What If? Lab What if an asteroid struck the Moon? The Moon's craters are a record of space rocks landing over billions of years, and small ones still land there every day. Scientists watch for tiny flashes of light on the Moon and later find the brand-new craters. Explore what happens when a rock hits the Moon, and why the Moon keeps going around Earth as always.
- Watch What If? Lab What if a day lasted 48 hours? Earth spins once about every 24 hours, and almost every living thing has a body clock tuned to that day. Imagine a day twice as long: long, bright days and long, dark nights. What would happen to your sleep, to plants and to animals?
- Watch What If? Lab What if Earth were the only planet? Imagine a solar system with just the Sun, Earth and our Moon. The bright 'wandering stars' would vanish from our night sky, the paths of asteroids and comets would change, and scientists would lose the other worlds that teach us how planets work. Explore what Earth would miss.
- Watch What If? Lab What if you visited an icy moon? Jupiter's moon Europa and Saturn's moon Enceladus are covered in ice, but scientists think salty oceans lie underneath. The squeezing pull of their giant planets keeps the insides warm. Imagine walking on the ice, peeking at the ocean below and joining the search for places where life could exist.
- Watch Try it What If? Lab What if Earth had no Moon? The Moon's pull stretches Earth's oceans and gives us most of our tides. Take the Moon away in our tide model and see what is left: the Sun still makes tides, but they are less than half as big as the Moon's.
- Watch Try it What If? Lab What if Earth had two moons? Our Moon goes round Earth in a neat, repeating loop. Add a second moon in our orbit model and watch what changes: the two moons tug on each other as well as on Earth, so their paths start to wobble.
For parents & teachers
What children will learn
- Jupiter is a gas giant with no solid surface.
- Gravity at Jupiter's cloud tops is about two and a half times Earth's, so weight would more than double.
- Jupiter's fast spin shapes its banded clouds and long-lived storms.
- Robot spacecraft such as Juno study Jupiter from orbit.
Recommended ages: 7 to 17 · About 15 minutes
Talk about it
- How would you design a probe to study a planet with no ground?
- Why do you think Jupiter's storms last so much longer than storms on Earth?
- Which parts of this what-if are measured facts, and which are imagined?
Try at home or in class
- Fill a backpack until it weighs about one and a half times as much as normal and walk across the room: a small taste of carrying extra weight. (Keep it light enough to be comfortable.)
- Stir a glass of water quickly, add a drop of food coloring and watch the swirl. Compare it with pictures of Jupiter's storms.
Key vocabulary: gas giant, gravity, weight, storm, spacecraft
Where these facts come from
- Jupiter Facts , NASA Science
- Jupiter Fact Sheet , NASA Goddard Space Flight Center
- Planetary Fact Sheet (Metric) , NASA Goddard Space Flight Center
Checked, not yet human-reviewed. Last updated October 23, 2026. Spotted a mistake? Tell us.