Jupiter: Crash Course Astronomy #16

Summary

This script offers an in-depth exploration of Jupiter, the largest and fastest-spinning planet in our solar system. It delves into Jupiter's gas giant status, its dynamic atmosphere with belts and zones, and the iconic Great Red Spot—a colossal, long-lasting storm. The script also discusses Jupiter's internal structure, including its possible lack of a core and its mostly liquid metallic hydrogen interior. It highlights Jupiter's role in the solar system, from its heat emission to its gravitational influence on other celestial bodies, and its potential protective effect for Earth against cometary impacts.

Takeaways

• 🌌 Jupiter is the largest planet in the solar system, with a volume that could contain all other planets with room to spare.
• 🌀 As a gas giant, Jupiter is characterized by its rapid rotation, completing a day in just 10 hours, the fastest of any planet.
• 🌞 Despite its distance from the Sun, Jupiter is one of the brightest objects in the night sky due to its ability to reflect a lot of sunlight.
• 🔭 The planet's four largest moons, discovered by Galileo, are visible with binoculars or a small telescope, and are considered worlds in their own right.
• 🌈 Jupiter's atmosphere displays banded stripes known as zones and belts, which are formed by convection and change in color and shape over time.
• 🌪️ The Great Red Spot is a massive, long-lasting storm larger than Earth with wind speeds of 500 kph, and is thought to be stable due to Jupiter's rapid spin.
• 🌈 The Red Spot's color is likely due to cyanide-like molecules, and it has been observed to change size and color over time.
• 🌪️ Jupiter's turbulent atmosphere is host to numerous storms, formed by the interaction between zones and belts.
• 🌌 Jupiter's thick atmosphere, composed mainly of hydrogen and helium with traces of ammonia and methane, deepens into a liquid metallic hydrogen layer under extreme pressure.
• 🔥 The metallic hydrogen layer is extremely hot, around 10,000° C, and conducts electricity due to the shared electrons among hydrogen atoms.
• 💎 The existence and composition of Jupiter's core are uncertain, with theories suggesting it may not have a core or that it could be composed of rock and metal.
• ✨ Jupiter emits more heat than it receives from the Sun, and this internal heat drives the atmospheric phenomena such as belts, zones, and storms.
• 🌐 Jupiter has a strong magnetic field, likely due to the metallic hydrogen inside, which results in aurorae at its poles.
• 💍 The planet also has a ring system, discovered by space probes, composed of dust possibly from meteorite impacts on its moons.
• 🌠 Jupiter experiences frequent impacts from interplanetary debris, which may have both protective and hazardous effects on the inner solar system.

Q & A

What is Jupiter known as in the solar system?

Jupiter is known as the 'King of the Planets,' the 'big guy,' 'top dog,' 'big cheese,' 'head honcho,' and 'one and only' in the solar system.

Why is Jupiter considered the largest planet in the solar system?

Jupiter is considered the largest planet because it is so massive that all other planets could fit inside it with room to spare, and it is 11 times wider than Earth.

How long is one day on Jupiter in terms of Earth hours?

One day on Jupiter, which is its rotation period, is only 10 hours long, making it the fastest spin of any planet in the solar system.

Why is Jupiter one of the brightest objects in the night sky?

Jupiter is one of the brightest objects in the night sky because it reflects a lot of sunlight, even though it is quite far from the Sun at an average distance of about 800 million kilometers.

Who discovered Jupiter's four biggest moons and what can be said about these moons?

Galileo discovered Jupiter's four biggest moons, which are worlds in their own right and are visible with binoculars or a small telescope if not hidden by the planet's glare.

What are the lighter and darker stripes on Jupiter's atmosphere called and what causes them?

The lighter-colored stripes on Jupiter's atmosphere are called zones, and the darker ones are called belts. They are caused by convection in Jupiter's atmosphere, with upwelling air forming white ammonia clouds (zones) and sunlight affecting the chemistry in the clouds to create the darker belts.

What is the Great Red Spot and how is it significant?

The Great Red Spot is a colossal hurricane on Jupiter that is several times larger than Earth, with sustained wind speeds of 500 kph. It is significant because it has been observed for over three centuries and is a major storm system on the planet.

Why is Jupiter considered to have a rapid spin despite its size?

Jupiter is considered to have a rapid spin because it completes a rotation in just 10 hours, which is the fastest rotation of any planet in the solar system, despite its large size.

What is the composition of Jupiter's atmosphere and how deep is it?

Jupiter's atmosphere is mostly hydrogen and helium, similar to the Sun, but also contains ammonia, methane, and other poisonous gases. It is several hundred kilometers deep.

What is the nature of the region below Jupiter's atmosphere and why is it considered unusual?

Below Jupiter's atmosphere is a huge region made up of liquid metallic hydrogen, which is unusual because under the high pressures inside Jupiter, hydrogen acts more like a metal and can conduct electricity.

Why does Jupiter emit more heat than it receives from the Sun?

Jupiter emits more heat than it receives from the Sun because it is still actively cooling since its formation 4.5 billion years ago. The cooling and contraction of its gaseous atmosphere increases internal pressure, which in turn generates heat.

What is the role of Jupiter in the solar system regarding comets and potential impacts on Earth?

Jupiter's gravity can either fling comets away into interstellar space, potentially protecting Earth from impacts, or it can warp their orbits causing them to swing by Earth. Its overall influence on the solar system's safety is still a subject of debate.

Outlines

00:00

🌌 The Colossus of the Solar System: Jupiter

This paragraph introduces Jupiter as the largest planet in the solar system, emphasizing its massive size—11 times wider than Earth and with a mass over 300 times greater. It's a gas giant with rapid rotation, completing a day in just 10 hours, the fastest of any planet. Jupiter's brightness, despite its distance from the Sun, makes it a prominent sight in the night sky. The paragraph also touches on Jupiter's observable features through binoculars or a small telescope, including its four largest moons discovered by Galileo. The atmospheric bands of Jupiter, consisting of zones and belts, are highlighted, along with the phenomenon of their circulation and occasional disappearances. The Great Red Spot, a massive, long-lasting storm, is also mentioned, with its size, wind speeds, and possible reasons for its stability and color variations discussed.

05:02

🌀 Jupiter's Formation, Composition, and Dynamics

The second paragraph delves into the formation theories of Jupiter, suggesting it may have originated from either a rocky metallic core that gathered gas or from the collapse of the protoplanetary disk into large clumps. It explores the possibility that Jupiter might not have a core at all. The paragraph also describes Jupiter's rapid rotation causing it to be noticeably flattened at the poles. It dispels the myth of Jupiter being a 'failed star,' clarifying that it lacks the mass necessary for nuclear fusion. Jupiter's unique heat emission, exceeding the heat it receives from the Sun, is attributed to its ongoing cooling process since formation. The internal heat is also responsible for the atmospheric belts, zones, and storms. The paragraph concludes with a discussion on Jupiter's strong magnetic field, its ring system, and its role in deflecting or redirecting cometary impacts that could otherwise threaten Earth.

10:05

🎬 Behind the Scenes of Crash Course Astronomy

The final paragraph provides credits and production notes for the Crash Course Astronomy episode. It mentions the script was written by Phil Plait, edited by Blake de Pastino, and consulted by Dr. Michelle Thaller. The episode was co-directed by Nicholas Jenkins and Michael Aranda, edited by Nicole Sweeney, with graphics provided by Thought Café. The paragraph also invites viewers to explore more content on PBS Digital Studios' channel.

Keywords

💡Jupiter

Jupiter is the largest planet in our solar system, often referred to as the 'King of the Planets.' It is a gas giant, which means it is predominantly composed of hydrogen and helium. The video script emphasizes its enormous size, stating that it is 11 times wider than Earth and has a mass over 300 times that of our planet. Jupiter's size and gaseous composition are central to understanding its role and characteristics within the solar system.

💡Gas Giant

A gas giant is a term used to describe planets that are predominantly made up of gases rather than solid materials. In the script, Jupiter is identified as a gas giant, highlighting its composition and distinguishing it from rocky or terrestrial planets. The concept is crucial for understanding the planet's physical properties and its dynamics, such as its rapid rotation and lack of a solid surface.

💡Rotation

Rotation refers to the spinning of a celestial body around its own axis. The script mentions that Jupiter has the fastest rotation of any planet in the solar system, with one day on Jupiter lasting only 10 hours. This rapid rotation contributes to Jupiter's distinctive flattened shape and is a key factor in understanding its atmospheric dynamics.

💡Atmosphere

The atmosphere of a planet is the layer of gases surrounding it. Jupiter's atmosphere is highlighted in the script for its depth, composition, and the phenomena it produces, such as belts and zones. The atmosphere is where the Great Red Spot, a massive storm, is located, and it is also where the planet's internal heat is radiated out as infrared light.

💡Belts and Zones

Belts and zones are alternating dark and light bands that run parallel to Jupiter's equator. The script describes these features as a result of atmospheric circulation, with upwelling air creating light-colored zones and sinking air forming darker belts. These patterns are a visual manifestation of Jupiter's dynamic weather system.

💡Great Red Spot

The Great Red Spot is a colossal storm on Jupiter, larger than Earth, with wind speeds of 500 kph. The script describes it as a persistent hurricane that has been observed for centuries. Its stability is attributed to Jupiter's rapid rotation, and its red color is likely due to the presence of certain chemicals. The Great Red Spot is a significant feature of Jupiter's atmosphere and weather.

💡Metallic Hydrogen

Metallic hydrogen is a phase of hydrogen that behaves like a metal under high pressure. The script explains that deep inside Jupiter, where the pressure is immense, hydrogen exists in a metallic form, capable of conducting electricity. This layer of metallic hydrogen is part of Jupiter's unique internal structure and contributes to its magnetic field.

💡Magnetic Field

A magnetic field is a region around a body within which the force of magnetism acts. Jupiter has a very strong magnetic field, likely due to its core of metallic hydrogen and rapid rotation. The script mentions aurorae at Jupiter's poles, which are caused by the interaction of the solar wind with this magnetic field. The magnetic field is a key aspect of Jupiter's interaction with its environment.

💡Impact

An impact refers to the collision of a celestial body with another. The script recounts the impact of comet Shoemaker-Levy 9 with Jupiter in 1994, which left visible scars for months. Impacts are significant events that can alter a planet's atmosphere and are part of the dynamic processes occurring in the solar system.

💡Aurorae

Aurorae are natural light displays in the sky, typically seen near the Earth's poles, caused by the collision of solar wind with the planet's magnetic field. The script mentions that Jupiter also has aurorae at its poles, a result of its strong magnetic field interacting with the solar wind. This phenomenon is a visual indicator of Jupiter's magnetic activity.

💡Protoplanet

A protoplanet is an early stage in the formation of a planet, where smaller particles of material come together through collisions. The script discusses two theories of Jupiter's formation, one of which involves the growth of protoplanets that eventually merged to form Jupiter. Understanding protoplanets is essential for grasping the early stages of planetary formation.

Highlights

Jupiter is the largest planet in the solar system, with all other planets fitting inside it with room to spare.

Jupiter is a gas giant, being both gassy and enormous, with a size 11 times wider than Earth and a mass over 300 times greater.

Jupiter has the fastest rotation of any planet in the solar system, with a day lasting only 10 hours.

Despite its distance from the Sun, Jupiter is one of the brightest objects in the night sky due to its ability to reflect a lot of sunlight.

Galileo discovered Jupiter's four biggest moons, which are visible with binoculars or a small telescope.

Jupiter's atmosphere features banded stripes known as zones and belts, formed by convection and the planet's rapid rotation.

The Great Red Spot is a colossal hurricane on Jupiter, larger than Earth with sustained wind speeds of 500 kph.

The Great Red Spot has been observed for centuries, showing stability unusual for a storm.

Jupiter's atmosphere is hundreds of kilometers deep, composed mainly of hydrogen and helium with traces of ammonia and methane.

Beneath Jupiter's atmosphere lies a unique layer of liquid metallic hydrogen, which behaves like a metal due to high pressure.

Jupiter's core is uncertain; it may not exist or could have been eroded away by hot metallic hydrogen currents.

Jupiter's formation could have involved collisions of large protoplanets or the collapse of the gas disk into clumps.

Jupiter's rapid rotation causes it to be noticeably flattened at the poles compared to the equator.

Jupiter emits more heat than it receives from the Sun, actively cooling since its formation 4.5 billion years ago.

Jupiter's internal heat drives its weather patterns, unlike Earth which relies on solar heat.

Jupiter has a strong magnetic field due to its metallic hydrogen core and rapid rotation.

Jupiter's ring system was discovered by space probes and is composed of dust likely from meteorite impacts.

Jupiter's gravity may protect Earth by deflecting comets, but it can also alter their orbits to approach our planet.

Jupiter is often inaccurately referred to as a 'failed star', but it lacks the mass required for nuclear fusion.

Transcripts

As we take our grand tour of the solar system here on Crash Course Astronomy, we’re going

to skip over the asteroids for now—we’ll get to ‘em, I promise—and instead pay

a visit to the King of the Planets, the big guy, the top dog, the big cheese, the head

honcho, the one and only: Jupiter.

Jupiter is the largest planet in the solar system. It’s not even close: All the other

planets could fit inside it with room to spare. It’s a gas giant, which means it’s gassy,

and... giant.

And I do mean giant. It’s 11 times wider than Earth—more than a thousand Earths could

fit inside it, and it has a mass over 300 times that of our planet. Despite its bulk,

it rotates extremely rapidly: One day on Jupiter is a mere 10 hours long! That’s the fastest

spin of any of the planets in the solar system.

Not surprisingly, a planet that big can reflect a lot of sunlight, and even though it orbits

the Sun on average at a distance of about 800 million kilometers, it’s one of the

brightest objects in the night sky.

With binoculars or a small telescope, Jupiter is a wonder. You can easily see it as a disk,

and its four biggest moons are readily visible—if they weren’t hidden by the planet’s glare,

they’d be naked eye objects. Galileo himself discovered those moons.

They’re worlds in their own right, and so we’ll dive into

them—literally—in the next episode.

When we look at Jupiter we’re not seeing its surface. We’re seeing the tops of its

clouds, and they’re a strange mix of permanence and change. The atmosphere of Jupiter is banded,

with multiple stripes running parallel to its equator. The lighter-colored stripes are

called zones, and the darker ones belts. They’re fairly stable, though their shape and coloring

change over time.

Belts and zones circulate around the planet in opposite directions. They form due to convection

in Jupiter’s atmosphere. Upwelling air cools and forms white ammonia clouds; that creates

the light colored zones. That air flows to the sides and sinks, and sunlight changes

the chemistry in the clouds forming molecules that color the air yellow, red, and brown.

This is what causes the darker belts.

In May of 2010, one of Jupiter’s biggest belts sank so deeply it disappeared from view

completely, covered by other clouds! Then, a few months later, it popped back up and

reappeared, none the worse for wear. This has happened several times in the past, too.

I saw one of these events once through a telescope, and Jupiter looked really weird. Lopsided.

Turbulence in the regions between zones and belts can create storms, gigantic vortices

raging in the clouds. Dozens of them dot the face of Jupiter all the time, but there is

one to rule them all: the Great Red Spot, a fittingly huge storm for a giant planet.

It’s actually a colossal hurricane, several times larger than our entire planet Earth,

with sustained wind speeds of 500 kph. And it’s old; it was first seen in the late

17th century—imagine a storm on Earth lasting for more than three centuries! And it may

be far older; the 1600s is just when we first… spotted it.

So, why is it so stable? It turns out that a vortex, a local spinning region in a fluid,

can persist if the fluid in which it’s embedded is itself rotating. Jupiter’s rapid spin

is what keeps the Red Spot circulating! And the redness is probably due to cyanide-like

molecules that absorb blue light, letting redder light pass through.

Weirdly, the Red Spot appears to be shrinking! It was substantially bigger and more elongated

just a few decades ago. It changes color over time, too, having gone from deep red to salmon

and then back again. No one knows why its shape, size, and color change, but given how

long the Spot’s been around, I doubt it’s going to evaporate any time soon.

Remember, we’re only seeing the tops of the clouds on Jupiter. Its atmosphere is thick,

several hundred kilometers deep! Like the composition of the Sun, the air on Jupiter

is mostly hydrogen and helium, but it’s also laced with ammonia, methane, and other

poisonous gases.

As you dive into Jupiter’s atmosphere, the pressure increases with depth. But you’ll

never reach the surface; the planet doesn’t really have a proper surface. The gas gets

thicker and hotter, and eventually just sort of smoothly changes into a liquid over a several

hundred km range below the clouds.

Below that is where things get really weird. Instead of a mantle, like terrestrial planets,

Jupiter has a huge region made up of liquid metallic hydrogen. We think of hydrogen as

being a gas, or, if it gets really cold, a liquid. But under the ridiculous pressures

generated deep inside Jupiter, hydrogen undergoes this strange transformation. Individual atoms

don’t hold on to their electrons, but instead share them. This means the hydrogen can conduct

electricity, and has other properties more like a metal. This substance is hot, too:

about 10,000° C, hotter than the surface of the Sun! If we could see it, it would glow

tremendously bright.

Finally, at its center is most likely a dense core of material, probably composed of rock

and metal. We really don’t know, because it’s incredibly difficult to understand

the physics and chemistry of material locked in at those pressures and temperatures. What’s

weirder is that we’re not even sure if Jupiter has a core! If it did, it’s possible it

was eroded away by currents of hot metallic hydrogen early on in Jupiter’s formation process.

It’s also possible it never had a core in the first place.

The solar system formed from a flat disk of gas and dust. The center of this disk is where

the Sun was born, and it’s thought that the planets formed as smaller particles of

material stuck together during random collisions farther out in the disk. As they got bigger—much

bigger—these protoplanets eventually started to grow even faster by drawing in material

around them due to their gravity.

Jupiter formed where the disk was thick, rich with material. It’s possible that several

large protoplanets were forming, collided, and stuck together to really kickstart Jupiter’s

growth. If that were the case, it started out with a rocky metallic core, and once it

got big enough it drew in that gas that made it the giant we see today.

Another idea is that Jupiter didn’t grow from the bottom up, but from the top down:

The disk itself collapsed in several places to form huge, distended clumps. These then

would have collided, stuck, and created the planet. If that’s the case, then Jupiter

might not have a core at all.

These two different mechanisms make different predictions about Jupiter’s structure, and

that means that, hopefully, we can eventually figure out which is correct by studying Jupiter

more carefully. But at the moment we still don’t know.

Either way, Jupiter grew immense, and it’s mostly liquid under all that atmosphere. Couple

that with its rapid rotation, and you can see it’s noticeably flattened! It’s wider

at the equator than through the poles by about 6% due to centrifugal force.

So, Jupiter is a big bruiser of a planet. But how close was it to becoming a star?

Sometimes, people ask me if Jupiter is a “failed star”; in other words, as it formed it almost

got massive enough that nuclear fusion could start in its center, turning it into a star.

I see this a lot on TV shows and in articles, and it really burns me up.

When a star forms, hydrogen fusion starts when the star gathers so much mass that its

gravity can compress atoms together in its core hard enough to get them to fuse. This

happens when a star has roughly 1/12th of the Sun’s mass. In fact, the smallest stars

we see do have about that mass.

What about Jupiter? The mass of Jupiter is about 1/1000th the mass of the Sun, far too

little to undergo fusion in its core. If you want to turn Jupiter into a star, you’d

have a lot of work ahead of you: You’d have to take Jupiter… and then add about 80 more

Jupiters to it!

Saying Jupiter is a failed star is really unfair. It’s not a failed star. It’s a

really successful planet.

Even though Jupiter isn’t a star, it does have another funny property: It emits more

heat than it receives from the Sun.

The Earth and other terrestrial, rocky planets are in a heat balance with the Sun; we emit

pretty much the same amount of heat that we receive. But Jupiter is different. After it

formed, it started to cool by radiating away heat from its upper atmosphere. A large fraction

of the planet is gas, remember, and when you cool a gas in contracts. So the atmosphere

cools and contracts, but this increases the pressure inside the planet, so it heats up!

That heat works its way out of Jupiter, and gets radiated away as infrared light. In the

end, the amount of heat Jupiter gives off is more than it receives from the Sun. It’s

still actively cooling, 4.5 billion years after it formed! Oh and hey, remember the

belts and zones, the stripes we see in Jupiter’s atmosphere, and all the storms that pop up?

Those are driven in large part by Jupiter’s internal heat. On Earth our weather is powered

by heat from the Sun, but on Jupiter they get their energy from the planet itself!

Jupiter has a very strong magnetic field, no doubt due to all of that metallic hydrogen

inside it coupled with its rapid rotation. Like Earth it has aurorae at its poles as

the solar wind is funneled down to the cloud tops. As we’ll see next week, Jupiter’s

moons affect the magnetic field and aurorae on Jupiter as well.

Jupiter also has a ring, though it’s not nearly as grand as Saturn’s. It wasn’t

even discovered until we sent space probes to the planet. The ring is made of dust, probably

thrown into orbit around the planet due to meteorite impacts on its smaller moons.

Speaking of impacts, we know that Earth gets hit by interplanetary debris all the time:

Go outside for an hour and you’re bound to see a few meteors. Jupiter, being larger

and with more gravity, gets hit a lot more. A lot. A lot more. And sometimes it gets hellaciously

whacked. In 1994, the comet Shoemaker-Levy 9 impacted Jupiter. Multiple times: Jupiter’s

fierce gravitational tides had ripped the comet into dozens of pieces, and each slammed

into the planet one after the other with the force of millions of nuclear weapons. The

scars left in the upper atmosphere from the plumes of material that exploded outward lasted for months.

Several smaller impacts have been seen in Jupiter’s atmosphere since then, and it

may suffer an impact large enough to see from Earth every year or so.

And while that sounds scary, it might actually be our savior. There’s an idea that Jupiter’s

gravity tends to take comets that fall toward the inner solar system and fling them away

into interstellar space. Over the eons, this has cleaned out a lot of otherwise dangerous

objects that could have eventually hit Earth. On the other hand, Jupiter has a tendency

to warp the orbits of some other comets so that they do swing by the Earth. It’s hard

to say if Jupiter’s influence is a net benefit or not.

But either way, it’s clearly the 2 septillion ton gorilla in the solar system.

Today you learned that Jupiter is really, really big. It’s the biggest planet in our

solar system, a gas giant. It has a dynamic atmosphere, including belts and zones, and

a gigantic red spot that’s actually a persistent hurricane. Jupiter is still warm from its

formation, and has an interior that’s mostly metallic hydrogen, and it may not even have

a core. It has the fastest spin of any planet, and it’s not a failed star.

Crash Course Astronomy is produced in association with PBS Digital Studios. Head on over to

their channel to discover more awesome videos. This episode was written by me, Phil Plait.

The script was edited by Blake de Pastino, and our consultant is Dr. Michelle Thaller.

It was co-directed by Nicholas Jenkins and Michael Aranda, edited by Nicole Sweeney,

and the graphics team is Thought Café.