Top Ten Facts About Jupiter
10. Jupiter is the Father of the Planets.
By far the most massive planet in our solar system, Jupiter is so big that all of the other planets combined would fit inside it!
Jupiter lends its name to "gas giant" class of planets in our solar system, which includes the four outer planets - Jupiter, Saturn, Uranus and Neptune. They are called the jovian ("Jupiter-like") planets because they are all significantly larger than the inner terrestrial ("Earth-like") planets and markedly different in composition. The jovian planets are mainly made of gas and ice, while the inner planets are composed largely of rock and metal.
So why are the outer and inner planets so different? The answer lies in condensation, determined by where each formed. At the beginning of our solar system, there was a lot of debris everywhere—rock, ice, metal, etc. The pieces would smash into each other, growing ever larger. This process is called accretion, and is similar to using a large ball of Play-Doh to pick up other smaller pieces—thereby increasing the size of the original ball.
The inner, or terrestrial, planets formed near the Sun. There, temperatures are more suitable for the formation of rock and metal; so that's what was there, smashing into each other and building up planets like our Earth.
Much farther from the Sun, where the jovian planets formed, the colder temperatures allowed gas and ice to condense, too. Through the process of accretion, it built up to the formation of the planets we now know.
9. If it were more massive, Jupiter would have ignited as a star.
Our Sun is made mainly of hydrogen and helium. So is Jupiter! According to NASA, if Jupiter had been about 80 times bigger than it is, it would have become a star instead of a planet.
Jupiter's atmosphere is composed almost exclusively of hydrogen and helium, with trace amounts of other things like methane and ammonia. Much is still unknown about the composition of Jupiter itself, which is why Juno is studying it now (see #1, below).
8. Gravity on Jupiter is more than double what we experience on Earth.
If you're looking to lose weight, stay away from Jupiter! The force of gravity on Jupiter's surface is about 2 1/3 time as strong as what we experience here on Earth. If you weigh 150 pounds on Earth, you would weigh about 380 pounds on Jupiter!
Weight is a measure of gravity's pull on something, so it can change based on location. The factors affecting gravity are mass and distance. On Earth, we experience the gravity that we do because of how far we are from the center of the Earth and the amount of mass that it's composed of.
On Jupiter, surface-level is MUCH farther from the center than it is here, since the planet is so huge—but gravity is still much stronger because of its incredible amount of mass.
7. Jupiter is freezing, but its core is hotter than the surface of the Sun!
Earth orbits about 93 million miles from the Sun. Jupiter is over five times farther - nearly 500 million miles! Understandably, it's much colder that far away from the Sun's warmth. Planetary atmospheres also play a role in temperature. Note in the figure above that Mercury's average temperature is more than twice as cold as Venus, though also nearly twice as close to the Sun. The difference is that Mercury has very little atmosphere, whereas the atmosphere on Venus is very thick. That helps Venus lock in heat, while much of Mercury's escapes.
Though the average temperature at Jupiter's surface level is -170 degrees Fahrenheit, other parts of Jupiter can be colder or much hotter than that. In the clouds, for example, temperatures range from -190 to 26 degrees Fahrenheit, depending on things like composition.
What's interesting, considering that Jupiter is so incredibly cold, is that its core is believed to be exceptionally hot. It is thought to be around 43,000 degrees Fahrenheit. If correct, that makes the core of Jupiter over four times hotter than the surface of the Sun! Jupiter is extremely massive, which means there's a lot of material pressing down on the core from all sides. This pressure aids in raising the core's temperature to such a toasty degree.
6. A year for Jupiter lasts about 12 Earth years.
Since Jupiter is more than five times farther from the Sun than Earth is, it has to cover much more distance to complete a full revolution around the Sun. It's the same principle behind staggering the starting line for runners in a track event. If all the runners started in a straight line instead, the runner in the inside lane would have the shortest distance run. The distance to be run increases more and more as you approach the outermost lane.
But there's more to it in the case of orbiting planets. The farther a planet is from the Sun, the slower it travels in its orbit. That's because distance is a major factor in determining gravitational force (back up to #8 if you've forgotten!). The closer a planet is to the Sun, the more quickly it speeds along its orbit. For Jupiter, the orbital speed is about 8 miles per second. That sounds like a lot (and it is), but Earth travels at over 18 kilometers per second - about 2.3 times faster than Jupiter!
5. Jupiter doesn't have a true surface - its atmosphere thickens down into slush.
It's difficult to imagine a planet without a surface. On Earth, the surface of the planet or of a body of water is marked by a clear distinction between materials - air and solid earth, or air and water. But on Jupiter, the temperature and composition lead to much hazier transitions. Instead of having a solid surface, the atmosphere gradually thickens into slush as you plunge toward the planet's center, ultimately reaching a core made of a truly exotic fluid: liquid metallic hydrogen.
4. Jupiter's Great Red Spot is a storm 2-3 times the size of Earth.
Though Jupiter's year is much longer than ours, its day is less than half the length of an Earth day - only about 10 hours! Jupiter's speedy spinning creates monstrous wind and storms. Wind on Jupiter can reach over 400 miles per hour, producing storms of unimaginable proportions - most notably, the Great Red Spot.
The Great Red Spot is a terrifyingly enormous storm that's been raging for over 300 years. We know that Schwabe, an amateur astronomer from Germany, made record of it in 1831, but it may be the same as Cassini's "Permanent Spot," discovered in 1665. The storm is so large it could encompass the entire Earth with room to spare!
When it comes to this storm, scientists have more questions than answers. According to the Encyclopedia Britannica, "an exact theory that explains both its source of energy and its stability remains to be developed." For now, it persists as something of a mystery.
3. Jupiter has rings and at least 79 moons.
Though Saturn is the planet most famous for them, all of the jovian planets have ring systems. Jupiter's dusty ring system is composed of three primary components, known as the Halo, Gossamer and Main rings.
Jupiter also has at least 79 moons. The largest four are pictured above: Io, Europa, Ganymede and Callisto. They are known as the Galilean moons, after the Italian astronomer who discovered them: Galileo. Though they're all moons of the same planet, they are vastly different.
Io is a little larger than Earth's moon. It may have its own magnetic field, and it's the only moon known to have active volcanoes. It's actually the most volcanically active body in the entire solar system!
Contrast that with Europa. It's completely covered in ice; it has very visible cracks all over it (visible in the image above - Europa is the moon on the top left). Astronomers believe that a global ocean lies deep beneath the icy surface. If so, it could potentially be harboring life even as you read this! The possibility of life (or at least a habitable environment) on Europa is so compelling that NASA is planning a mission, Europa Clipper, to investigate it. It will launch sometime in the 2020s and will complete a series of flybys to study the moon.
Ganymede is a giant - it's even bigger than the planet Mercury, and easily the largest moon in the solar system. It's the only moon that astronomers know to have its own magnetic field, just as they suspect Io might.
The most cratered body in the solar system is Callisto. Like Europa, astronomers believe Callisto may harbor an ocean deep beneath its icy surface.
2. Jupiter's clouds are only about 40 miles thick.
Jupiter is famous for the stripy banding of its clouds. Scientists believe there are three separate layers with different compositions. Since the planet is so enormous you might expect Jupiter's atmosphere to be equally colossal, but it's actually relatively small. It's about 43,000 miles from the center of the planet to surface level but the clouds are only about 40 miles thick. They are held close to the planet by Jupiter's strong gravity, but they're roiling and churning in supermassive storms since they aren't slowed down by a solid surface.
1. Juno is a current mission by NASA to learn more about Jupiter.
In Roman mythology, Jupiter (among many, many other ancient gods) was known for abducting goddesses and mortals. Jupiter's moons are named for these individuals. Marilyn Morgan, of the NASA Jet Propulsion Laboratory, notes that these names are "an appropriate choice since the moons of Jupiter are indeed caught in its gravitational pull."
Because he wanted to hide his mischievous doings, Jupiter is said to have surrounded himself in a shroud of clouds. The only one who could see through them was his wife: Juno.
Juno is a very exciting mission, which arrived at the planet in July 2016. Its goals include studying Jupiter's clouds, gravitational field, planetary composition and the auroras caused by its strong magnetic field. It is in a polar orbit, which allows us to characterize the planet's perplexing poles.
So far, we've learned that instead of the planet being pretty stable and solid, it seems that Jupiter's layers are mixing and churning. We've also discovered even more supermassive storms, such as the one pictured above, and a much stronger magnetic field than previously thought.
So many things about Jupiter remain shrouded in mystery, but hopefully Juno will allow us to see past the obscurity.
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© 2014 Ashley Balzer