Jupiter is the fourth brightest object in the Solar System when viewed from Earth. (The Sun, Moon, and Venus are brighter.)
The ancient Babylonians were the first to record Jupiter around the 8th century BC. That's almost 3,000 years ago!
Although Jupiter is named after the King of the Roman gods, the Greeks knew it as Zeus, the god of thunder. Germanic tribes saw the planet as Thor.
Jupiter revolves on its axis every 9 hours and 55 minutes. This gives it the shortest day out of all the planets!
Jupiter has a slightly flattened shape due to its extremely rapid spin.
However, from the perspective of Earth, Jupiter moves very slowly in the sky. This is because it takes over 11 Earth years to orbit the sun!
The Great Red Spot is actually a storm in Jupiter's atmosphere. It has been raging for over 300 years and is so big that 3 Earth's could fit inside it!
Jupiter's upper atmosphere is mostly clouds made of sulfur and ammonia. If you could smell it, it would stink!
Beneath the upper clouds, the rest of the atmosphere is primarily hydrogen and helium.
So what about the core? Well, Jupiter's gaseous atmosphere gradually transitions from gas into liquid. The planet may have a rocky core, but it likely lacks a solid surface.
Jupiter is actually known as a "failed star." This is because it contains the same mix of hydrogen and helium as other stars like the sun, but it never got big enough to start nuclear fusion.
In the Sun, hydrogen is essentially "crushed" until it becomes helium. This process (nuclear fusion) requires lots of internal pressure, which comes from being massive. So, if Jupiter had gotten just a little bigger, we would have had a 2-star Solar System!
There is water deep inside of Jupiter, although its concentration is very low.
One of Jupiter's moons, Ganymede, is the largest moon in the Solar System. In fact, it's bigger than Mercury!
Jupiter has 69 moons in total! That is more than any other planet in the Solar System. Only Saturn comes close with 62 moons. In fact, new moons are still being discovered!
The four largest moons are called Galilean moons. We've already met one - Ganymede. The other three are Lo, Europa, and Callisto. If they were circling the Sun, they would be considered Dwarf Planets.
On the topic of size, Jupiter is two times more massive than all the other planets combined!
Although they are harder to see than Saturn's or Uranus's, the rings of Jupiter extend from about 100,000 km above its atmosphere to almost 250,000 km above its atmosphere. They can be as thick as 12,000 km!
Jupiter is a very windy place. Average wind speed in the atmosphere can be anywhere from 192 mph to 400 mph.
Although the temperature in Jupiter's clouds is about -145 C, the temperature in its core is almost 24,000 C. That is hotter than the surface of the Sun!
If you were somehow standing at the very top of Jupiter's clouds, you would feel the force of gravity about 2.4 times stronger than on Earth's surface. So if you weighed 100 pounds here, you would weigh 240 pounds there!
Jupiter has the strongest magnetic field in the Solar System due to the huge ocean of liquid hydrogen deep beneath its clouds.
Jupiter's moon Europa is almost entirely liquid water beneath its icy surface. In fact, it has twice as much water as Earth!
More than 1,300 Earths would fit inside of Jupiter!
From 1979 to 2007, eight NASA spacecrafts studied Jupiter. As of this writing, a new spacecraft named Juno is studying Jupiter to help scientists understand how it was formed.
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