As we continue on our quest to get to know our galaxy better, we come to the 5th planet from the sun, Jupiter. Some of you may recognize it as the “Just” in the grade school mnemonic, My Very Educated Mother Just Served Us Nine Pizza's. We may not have nine pizzas, but we do have ten great facts about Jupiter for you to digest.
A 300 Year Storm
We spoke briefly about the strong weather patterns that Jupiter experiences, but we saved this little nugget for the very end. As damaging as Jupiter's storms are, you wouldn't initially think that one could last upwards of 300 years, but that's exactly what's happening in this gas giant's atmosphere. The very first up-close imagery of what's been named the Great Red Spot came from Voyager 1's journey in 1979, though initial observations of the storm have been dated as far back as 1665. There's speculation as to whether these earlier discoveries were one in the same, but it is known that the current spot has been under scrutiny since 1830. The 300 year old storm continues to dole out extreme winds exceeding 200 miles or 320 kilometers per hour.
Of Jupiter's 67 moons, the one that seems to stand out the most is Ganymede. Chances are it makes the biggest impression because it is the largest known moon within our Solar System. At 3,273 miles or 5,268 kilometers wide, Ganymede is nearly twice the size of Earth's moon. This oversized Galilean moon is so large that it's the 8th largest object in the Solar System, coming in just behind Mars and just ahead of Saturn's moon, Titan. One of Ganymede's more interesting features is the alleged saltwater ocean that rests 124 miles or 200 kilometers below its surface.
The Many, Many Moons of Jupiter
Though Galileo laid claim to four of Jupiter's moons, he had no idea that there were more lying in wait. In fact, the great astronomer was nowhere near finding every one of the gas giant's moons. Overall, there are 67 known satellites orbiting, and considering the latest of them was discovered only in 2011, there's a chance that more are out there. The moons range from the considerably small size of 1.2 miles or 2 kilometers to a much grander 3,273 miles or 5,268 kilometers in diameter. Fifty-one of Jupiter's satellites are considered irregular, meaning they were captured within the planet's orbit rather than having been formed in the orbit itself.
Though Galileo can't technically be credited with Jupiter's discovery, upon observation of the massive planet, he did stumble across some interesting characteristics. During his viewings in the early 1600s, Galileo came across four celestial objects surrounding Jupiter, moons that came to be known as Io, Europa, Ganymede, and Callisto. To commemorate Galileo's findings, the grouping of Jupiter's largest moons were later dubbed the Galilean moons. The discovery, though important to those intrigued by Jupiter, also marked a turning point in how the Solar System was viewed. Whereas everything was once believed to have revolved around Earth in the Ptolemaic world system, the Galilean moons showed that celestial bodies could orbit other objects in space.
Nobody has Claimed Jupiter’s Discovery
The discovery of most planets in our Solar System can be linked back to an individual or team of scientists, but there are a few that have an illusive history. Nobody in the modern world can be credited with the discovery of Jupiter as the massive, bright planet is one of only 5 planets that can be seen without technical assistance. What is known is that the Romans were the first to give Jupiter a formal name, fittingly after their supreme god and deity of thunder, lightening, and the sky. If a name must be associated with its discovery, Galileo Galilei was the first person to view the planet via telescope.
Jupiter is Home to Damaging Storms
Two facts ago, we mentioned how Jupiter experiences fast moving storms, but there's so much more to know about the giant's weather. On top of being fast moving, storms on Jupiter can grow to cover substantial areas and be incredibly damaging. We're talking growth of up to thousands of miles or kilometers wide within just a few hours. The planet's own heat source, found deep within the mixture of gases towards Jupiter's core, is primarily responsible for the moist convection that helps drive Jupiter's damaging weather patterns. The process is similar to Earth-formed storms, though the sun has nothing to do with the powerful lightening and damaging winds on this gas giant.
The Gassy Planet
We've all had those days where yesterday's extravagant dinner turns into a day of gaseous regret, but poor Jupiter goes through that on a daily basis. Jupiter is one of two gas giants in the Solar System, comprised primarily of hydrogen and helium at an approximate ratio of 90% to 10% respectively. Jupiter is one, big gaseous ball, so much so that if you tried to land on the planet's surface, you'd be sorely disappointed. What scientist's consider the "surface" of Jupiter is just the point where the atmospheric pressure is at an equivalent to Earths'.
Regardless of the 12 year orbital period, Jupiter actually has much shorter days than Earth. Where us Earthlings experience a 24 hour cycle, Jovians get to enjoy a day that's 9 hours and 56 minutes long. Why the shortened cycle? We're so glad you asked! It's all about how fast the planet spins, but since Jupiter doesn't have surface features to monitor rotation off of and the storms move way too fast for accurate readings, scientists had to base this figure off of Jupiter's magnetic field using radio emissions. It's still not entirely accurate, as different parts of Jupiter, such as the equator, rotate at different speeds and have slightly deviated day cycles.
Five Times Farther
If you look at a map of the solar system, you'll find that Mercury, Venus, Earth and Mars are relatively close to one another and are within 150 million miles or 249 million kilometers from the sun. Then there's Jupiter, which just had to be completely different and separate itself from the initial planetary quartet by approximately 300 million miles or 482 million kilometers. At its closest proximity, Jupiter is around 460 million miles or 741 million kilometers from the sun, making it nearly 5 times farther away from the Sun than Earth. Its extended distance means Jupiter takes just about 12 Earth years to orbit the sun.
The Biggest Planet
In fact, it’s quite larger than every other planet in the solar system. Jupiter comes in with a radius of 43,441 miles or 69,911 kilometers, which is almost 10,000 miles or 16,000 kilometers larger than the next largest planet, Saturn. In comparison to our lovely little planet, it would take 11.2 earths laid side-by-side to match the diameter of Jupiter. It’s believed that Jupiter’s massive size is responsible for directing the paths of smaller objects within the solar system, either sending comets or asteroids into or away from the inner solar system. Thanks Jupiter, you're awesome.