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THIS IS AN CONTINUING PAGE FROM MY FIRST HOMESIDE ABOUT THE SOLARSYSTEM
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JUPITER
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You gaze in wonder at a failed star.
Jupiter has more mass than all of the other planets put together. Its diameter is more than 11 times the size of Earth's. It radiates one-and-a-half times more heat than it receives from the Sun.
Jupiter is a ball of dense gas, each layer compressed by the layer above it. The core is so compressed that it has liquified into a ball more than 20 times the mass of Earth. Jupiter is the heaviest object in our solar system except for the Sun.
The outer planets formed differently from the rocky inner worlds. When our Sun blasted away the gases from the inner planets, they were caught and trapped by the outer planets. Jupiter trapped much of it, gaining in size and mass and growing hotter and hotter, until...
...Until it stopped. For all of its massive size, it was not massive enough to become a star. If it had been any denser, it might have ignited, like our Sun. Instead, Jupiter has remained a giant storm of hot, swirling gases.
You look into the swirling mass of clouds and find yourself in the midst of them. Chaos surrounds you. Winds roar past, buffeting you with zig-zagging air currents. Lightning flashes in jagged bolts. As you descend further, the pressure increases enormously.
Finally, you reach a huge ocean of liquid hydrogen, smooth except for a few sluggish waves that roll across its surface. This ocean is 114 times Earth's surface area. The ocean is freezing cold, and the sky above it is pitch black. The only visible light comes from the brief, brilliant flashes of lightning that streak across the sky.
You fly up into the atmosphere, rising until you reach one of the highest levels of the planet's many layers. Here, the atmosphere is as thick and blue as Earth's, but the air is made up of hydrogen, helium, and ammonia instead of oxygen. The wispy white clouds are not water vapor, but ammonia crystals. Below, you can see massive storms and bolts of lightning.
You fly higher, until you are above the entire planet. Below, you can see storm patterns that have not changed for centuries. One of these, the Great Red Spot, could swallow three Earths. The storms bump and push past each other, forming bands of clouds that constantly whirl around the planet.
Above, you can see the Sun -- only a fifth of the size we see from Earth. You can also see the numerous moons that orbit this giant planet like a miniature solar system. Each is unique -- as diverse as the Sun's orbiting planets.
You are surprised to notice that Jupiter has a ring. The ring is too thin to be seen from Earth. It is made up of tiny dust grains. These particles lazily spiral around the planet, ultimately drifting down onto its surface.
Tearing your gaze away from this fascinating planet, you force yourself to look further out into the solar system. In your mind's eye, you picture another giant planet with huge, shining rings. You focus your mind on your next destination -- Saturn.
To learn about Saturn and its magnificent rings, TURN TO THE NEXT TOPIC.
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SATURN
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Unlike stormy Jupiter, Saturn looks like a calm, serene jewel floating in the sky. Floating is an appropriate description. Although it is the second largest planet in the solar system, it is the lightest. Made up almost entirely of hydrogen, it would float in water like a giant inner tube.
If Jupiter is a failed star, then Saturn is an ambitious planet, spinning on its axis at a furious pace. A day on Saturn lasts a little over 11 hours. The speed of its rotation is so great that the equator bulges. You would weigh less at Saturn's equator than you would anywhere else on the planet's surface.
Like Jupiter, Saturn radiates more heat than it receives from the Sun. While it may appear calm on the surface, the haze of hydrogen in the upper atmosphere hides clouds and winds that rush at tremendous speeds, agitated by the planet's inner heat. The winds of Saturn gust at 1,800 km
(1,116 miles) per hour.
You notice that large white bubbles of hot gas occasionally emerge from the depths of the planet's atmosphere. If these bubbles turn into whirling storms, they can last for weeks -- sometimes, even for months.
Your attention cannot remain focused on the planet's surface for long. Your eyes are drawn to the magnificent rings that encircle the planet's equator. At first, you think there are only two huge rings separated by a gap of dark space. You look at them more closely and see that there are many more. Great rings are divided into bands of many rings.
You notice that the rings are made up of rock and ice particles that range from the size of a golfball to the size of a basketball. Saturn's many moons shape and guide the rings. The rings are about 272,800 km (170,000 miles) in diameter but less than a kilometer thick. You see that strange, intricate braided patterns are woven into the magnificent structure of the rings.
How did these rings form? Perhaps they are the remnants of a moon that never quite formed. Or perhaps a moon collided with a comet, causing both to shatter. Either way, the remains are now scattered in an orbit around Saturn's equator, creating perhaps the most beautiful sight in the solar system.
The rings are entrancing, but it is time to move on. You shudder. The outer gas giants are far from the Sun's warming rays. With regret, you leave Saturn's dazzling display and force your mind to move on to Uranus.
To learn about Uranus, TURN TO THE NEXT TOPIC.
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URANUS
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You are floating in the skies above Uranus, watching an aurora.
Electrically charged particles, trapped by the planet's magnetic field, cascade down through the sky, radiating spectacular colors as they hit gas molecules in the atmosphere. These auroras are 10 times brighter than any found on Earth.
Uranus is a strange world. It is tilted so far off its axis that it seems to revolve on its side -- much like a toy top that was knocked over. As the planet travels around the Sun, its north and south poles spend one-quarter of the year directly facing the Sun's rays.
Oddly enough, the magnetic north and south poles are in a completely different location from the geographic poles. Early in the planet's past, an Earth-sized object crashed into it. As the planet rolled over on its side, the internal dynamo that created its magnetic field did not quite tip over all the way. As a result, the magnetic poles are strangely skewed and do not line up with the geographic poles.
Uranus also changes its orbital path slightly from one circuit around the Sun to another. Neptune's orbit is also irregular. Some scientists speculate that the movement of an undiscovered Planet X might be causing these orbital fluctuations.
The winds are much calmer on Uranus. They race by at only 560 km (347 miles) per hour. Although Uranus radiates more heat than it receives from the Sun, the outer gas layers are still freezing cold. At its poles, temperatures can be as low as -176 C (-350 F).
The atmosphere is made up of hydrogen, helium, and methane. These gases absorb the Sun's red wavelengths, giving the planet a strange blue-green color. Uranus is completely different from Saturn and Jupiter.
Descending through the frigid atmosphere, you see the ocean that covers the entire planet. The sluggish waters are made up of water, ammonia, and methane. To your surprise, the ocean is scalding hot, heated from within by the planet's rocky, Earth-sized core.
Uranus has 11 rings, but they are completely different from those of Jupiter and Saturn. Because Uranus rests on its side, the rings do the same. Unlike the dazzling rings of Saturn, these rings do not reflect light. You can see that they are made up of dark, rocky material. Some of this material may even include organic matter.
What might have happened to this strange world if it were positioned closer to the Sun? Could life have thrived here? This world has been bowled over by an early accident. What if that accident had bumped it closer to the Sun's warming rays? Might this blue planet have evolved into something more like the one you left? With another shiver, you move on.
To learn about Neptune, TURN TO THE NEXT TOPIC.
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