Jupiter is a largest planet in the solar system. So let’s get the obvious question out of the way, how big is it? This is Earth compared to Jupiter. It would take more than a thousand earths to fill the fifth planet. But our journey today fixes a bulls eye on Jupiter. Most of the images you’ll see come from various spacecraft that made the trip.
For example, Voyager II collected this remarkable sequence in 1979. Movies of Jupiter are exceedingly rare. Most visiting spacecraft simply use Jupiter’s immense gravity as a slings hot for journeys elsewhere. Churning skies of roiling clouds compel the attention of even casual visitors. Jupiter’s face is an opaque, seething mask ever changing, revealing nothing of the small, dense core tens of thousands of miles below.
The planet’s extraordinary rotation speed keeps the grinding sky in constant motion. How fast is it? The huge planet makes a complete revolution in a mere ten hours compared to twenty-four on our little Earth. Winds howl constantly at almost three hundred miles per hour. With that much wind, strange things are bound to blow around.Like this the famous Red Spot.
The Red Spot is a rotating high pressure system weather, in other words and it’s a storm that’s been churning for well over a hundred years, likely observed in even the earliest telescopic observations of the planet. Just like our own planet, Jupiter changes everyday.
In July 1994, the comet Shoemaker Levy 9 fell into Jupiter’s gravitational thrall. The planet’s gravity ripped the wayward space traveler into roughly 21 pieces prior to impact. Shoemaker Levy 9 delivered a rain of chaos onto the cloud tops in Jupiter’s southern hemisphere. Blast zone plumes smeared across the planet’s face like campfire smoke caught in thunderstorm winds. It was months following the impacts until most of the debris cleared from cloud tops, washed over by the gas giant’s relentless atmosphere.
Had these celestial bombs fallen to Earth, they would have decimated the planet. But Shoemaker Levy 9 may be one of the best demonstrations of Jupiter’s great contribution to life on Earth. Jupiter’s massive gravity field may be the solar system’s vacuum cleaner that kept our own planet relatively impact free and allowed life to evolve. Jupiter’s massive gravity well holds more than 63 moons in orbit. It’s a symphony conductor, commanding delicate, temperamental strings in the front, and more sedate, tractable servants in the back.
Many of these worlds themselves are realms of mystery and wonder. Close to the giant, moons move at tremendous velocity, some zipping around the planet several times in a single Earth day. Further out the crowd thickens. Moons occupy orbital tracks approximately 20 million miles above the planet. The farthest ones may take more than two Earth years to make the elliptical trip.
But the big, famous ones travel in close. Here’s Io. Jupiter’s violent gravitational tides push and pull Io’s fragile structure. In response, the moon blasts angry bursts of volcanic fire above its blasted face. The big moons are all different, too siblings circling their parent. They exhibit diverse character, from rocky surfaces, to odd, dented shapes, to places beckoning explorers to paya.
Mysterious Europa may hide oceans, tantalizing us with the potential for life. Lines on the surface are really cracks in thick ice, suggesting fluid seas hiding more than two miles below. Ganymede, orbiting a little more than half a million miles from Jupiter, it’s the largest moon in the solar system bigger than even the planet Mercury.
In a similar orbit we find we find a place of quiet beauty. Sleepy Callisto shows the weary signs of age-old craters. It’s an icy jewel, a silent dolmen bathed in reflected Jovian light. Jupiter. Giant of the solar system, capture of the imagination. It is the Kilimanjaro to the wide open spaces of our solar system, and it pulls our curiosity and attention like a beacon when we look out into the darkness of space.