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Take a large drop of water. Very large - about a thousand kilometers across. Freeze it. The surface will crack and ripple. Then bombard it with assorted rocks and snowballs, large and small, for a few billion years. Finally, spray it with fresh crystals from the ice volcanoes of a sister-moon. [ABSTRACT FROM AUTHOR]

Andy Warhol's images of Marilyn Monroe and others, in sequences of extravagant color, help to define Western culture of the mid-twentieth century. He did not invent the use of false color, however. Mappers have long used different hues to represent different altitudes of the land. A negative photograph can reverse shades and present an image in a way that does not match the human eye's interpretation of the same scene - the coloring is not true. But it is interesting that the Warhol images predate the use of false color in scientific image making. [ABSTRACT FROM AUTHOR]

The sunlit rings of Saturn seem to unroll like a strip of fabric from the dark edge of the planet. This banded blanket apparently dominates a small moon, Prometheus, though the truth is that the moon is far larger than any of the ice particles of the rings. [ABSTRACT FROM AUTHOR]

Io races across the background of Jupiter's raging skies, a small rocky ball above a giant and gassy planet. And race it must. Stable orbit so close to a large host, where gravitational field is intense, is only possible at high speed, and Io finds this stability at 17 kilometers per second, making its long, long journey once around Jupiter in less than two Earth-days. [ABSTRACT FROM AUTHOR]

The Voyager 2 space mission was launched in 1977, and the spacecraft is now far beyond the orbit of Neptune traveling on outward at a speed of about 60,000 kilometers per hour. At that rate, it will reach the outermost extremes of the Oort Cloud in about 20,000 years, and will be at the distance of the nearest star after roughly 75,000 years. Radio signals now take 11 hours to reach us from the little probe, but reach us they do. It is still sending information, using a transmitter with a power of about 25 watt. To know what it has seen, we need sensitive receivers as well as an 11 hours wait. Voyager is on an epic journey of a hero. [ABSTRACT FROM AUTHOR]

There seems to be something electric about these simple lines, like streaking car lights or a fluorescent glow in some dark place. Some might say that they seem to have human rather than natural origins. But that would be to say that humans are not natural, not part of nature, which is an arrogant and unsustainable claim. Human involvement with the glowing lines begins with the imaging processes of the Cassini spacecraft - that's a profound involvement, and a natural one. [ABSTRACT FROM AUTHOR]

We have continents and we have seas. We have a thin layer of gas to separate us from the dark vacuum above. So does Titan. We have people, 6 billion and more, each enveloped in his or her own unique importance. Titan has none. [ABSTRACT FROM AUTHOR]

Some things are easy to see, and some things are not. Asteroids, for the most part, fall into the second category. But sometimes they give themselves away by their movement. [ABSTRACT FROM AUTHOR]

Not many people get to see Halley's comet more than once, since we each have too little time in the light of the Sun. If you weren't around in 1986, or just didn't look carefully enough, then you'll have to wait until 2061-2062. It visits every 76 years. [ABSTRACT FROM AUTHOR]

The picture is grainy. It could be an enlarged photo of distant airplane vapor trails, or, slightly more fancifully, a negative image of telephone wires in a snowy sky. It could be quite an old picture, and indeed it is, having been taken on January 23, 1986. [ABSTRACT FROM AUTHOR]

The surface of Saturn is generally cloudy, murky, and bland. But, as in this image, the gases of the far north of the planet can have the same effect on sunlight as does the Earth's much thinner and more fragile atmosphere. They scatter blue light to our eyes, or in this case to a camera on board the Cassini spacecraft. Onto these deep blue skies are cast the shadows of Saturn's rings, while over and around the planet speeds Mimas, one of the large family of moons. [ABSTRACT FROM AUTHOR]

It is an epic story, full of colorful characters, dangerous voyages, conflict and tragedy, and a big surprise. It is the story of how inhabitants of a planet became aware of what goes on beneath their feet. [ABSTRACT FROM AUTHOR]

The Moon exists in close gravitational association with the Earth. There are other bodies, also traveling around the Sun in the same length of time as our planet and at much the same average distance from the Sun. These move in complex patterns that can in no way be called orbits of the Earth. They are not our moons but our companions. [ABSTRACT FROM AUTHOR]

Imagine a scientist at work, trapped deep inside a building and receiving this image on her computer screen. She would, almost certainly, be struck by its beauty, and might want to think about what it shows, with a fresh mind, as if seeing such a sight for the first time. [ABSTRACT FROM AUTHOR]

The thin rings of Saturn form a straight line across the background of the planet while a small moon, Tethys, hangs below, in one of the spectacular images beamed back to Earth from the Cassini spacecraft. The result is a picture of harmony, and of apparent stillness. But it is the camera that has introduced the stillness, and has frozen the scene. The camera might not quite lie, but it presents a very limited truth. Time and change are part of nature's fabric, inseparable from the whole. In nature there are no frozen moments. [ABSTRACT FROM AUTHOR]

On Titan, every day is cloudy. It is dull too, illuminated only by a very distant Sun. On the bright side, though, the clouds are a cheerful orange color. [ABSTRACT FROM AUTHOR]

There are an awful lot of bodies in the Solar System, from the Sun itself to specks of dust. Among them there are submicroscopic, subatomic particles that leave dramatic traces even though individually they are profoundly undetectable from here on Earth. [ABSTRACT FROM AUTHOR]

It isn't always necessary to send missions into space in order to observe smaller bodies of the Solar System, nor to use sophisticated ground-based observations. Some of them come to us, and we have only to look upward to see the spectacle. [ABSTRACT FROM AUTHOR]

All of the outer planets have ring systems. Saturn's are by far the most flamboyant. Jupiter doesn't flash its rings around for all to see quite so obviously. From the darkness of the far side of Jupiter, the Galileo spacecraft saw sunlight scattered by the upper limits of Jupiter's atmosphere creating a fine arc of light. And reaching outward was another fine line - Jupiter's main ring, seen almost "edge-on." The ring is a tenuous strand of fine particles, misty-edged, and in this image its simplicity is its beauty. [ABSTRACT FROM AUTHOR]

Hell, traditionally, is below. Certainly there is plenty of fieriness deep beneath our feet, generated by the planet's own radioactivity, and sometimes manifesting itself at the surface with dire consequences. [ABSTRACT FROM AUTHOR]

More than 150 years ago, James Clerk Maxwell developed a mathematical prediction that the disk around Saturn could not be a rigid solid. A solid disk would fall apart, he said, thanks to gravity and its own orbital motion. Observations that could check his prediction, and support it, came much later; firstly from the spectrum of reflected light from the rings (about fifty years later), then from the Voyager spacecraft (more than a hundred years later), and recently by close-up imaging by the Cassini mission. The rings are grainy bands of ice, with disturbances trickling through them in time with the motions of nearby moons. [ABSTRACT FROM AUTHOR]

Intelligence, it seems, can arise on Earth. It's a fanciful idea, but imagine that there were sophisticated dinosaur technologies, advanced trading systems and global collaboration that surpass our own. Yes, it's fanciful, but no more so than the self-worshipping notion that the dinosaurs were some sort of evolutionary blunder and only now have we arrived as the supreme achievement of the Universe. [ABSTRACT FROM AUTHOR]

It's bigger than Pluto, and for a small part of its 560 year orbit around the Sun is actually closer to us than Pluto is. It has pretty much as much right to be called a planet. It was just discovered 70 years later, that's all. One consequence of the discovery was that Pluto was officially demoted to be merely a "dwarf planet," along with the new object (and with the large asteroid Ceres). [ABSTRACT FROM AUTHOR]

Enceladus is not an isolated sphere, existing without connection to others. Neither is it an island, existing without connection to others. Not only is its icy globe bound to Saturn, but it shuffles in time in a complex synchronicity with other moons. No moon is an island. [ABSTRACT FROM AUTHOR]

The Earth's terminator sweeps over us as certainly as death's scythe, but more often. Twice every day the circular edge of darkness creates a twilight zone for each of us, a boundary between sunlit day and the hours of the night. Miranda, a small moon of Uranus, has a terminator, too, of which this image shows just a small portion. [ABSTRACT FROM AUTHOR]

Looking at all of the planets and moons of the Solar System, there are similarities with the Earth - volcanoes here, liquid erosion there, fault lines somewhere else. But it is the diversity that is most striking and most wonderful. Each body has its own very unique story to tell. Learning to read those stories is a great adventure, and by increasing our understanding of other moons and planets, we come to know the Earth better. [ABSTRACT FROM AUTHOR]

There are, for 24 hours every day, many pairs of eyes looking into the skies. Some are the eyes of professional astronomers while others are making just casual glances. Early in 1997, a comet was visible to billions of people who needed only to look up. [ABSTRACT FROM AUTHOR]

The "ideal" is an aspiration that is beyond reality, but that is embedded in our culture. The fact that it lies outside our physical reach does not prevent us from wondering what perfection might look like. [ABSTRACT FROM AUTHOR]

The regular transitions of the Moon from crescent to globe and back again, as its sunlit half shifts in and out of our view, impact less on electric city existence than on the lives of our ancestors. Many of us have left the Moon behind and moved on. The night, however, remains central to ordinary life. [ABSTRACT FROM AUTHOR]

It is 33 kilometers long and 13 kilometers across, and it hangs in space far away from any planet. It is the asteroid Eros, a large and irregular stone, one of a horde of such rocks encircling the Sun, further out than Mars but not so far as Jupiter. [ABSTRACT FROM AUTHOR]

These are three images of one object that is the size of an iceberg. And it is indeed made, at least partly, of ice. But it does not float passively in water. It hangs in space, as do the Earth, the Moon, and the Sun, and it spins just as they do. But it spins faster. [ABSTRACT FROM AUTHOR]

There are drainage features leading from among the ranges of hills and down toward the lakes. Where in the world could this be? But a prior question should be "which world?" because this image is not of the Earth. [ABSTRACT FROM AUTHOR]

Pluto the god ruled the underworld, and was the god of gold and wealth, the god of death. Pluto, the distant object of the Solar System, came into human consciousness in 1930, and makes its long journeys around the Sun, for the most part, beyond the orbit of Neptune. [ABSTRACT FROM AUTHOR]

How many bodies are there in the Solar System? There is the Sun, of course, and eight planets, and there are the smaller bodies: some dwarf planets, comets mostly in the outer reaches (some of them as big as dwarf planets), asteroids, and other debris and dust. The dust is spread out well enough, but there is an awful lot of space and a lot of dust. There are electrons, protons, and ions, but there would be no point in even starting to count them. Numbers don't go that far. And there are moons, which do not have independent orbits around the Sun but travel with larger bodies. [ABSTRACT FROM AUTHOR]

Ganymede is larger than Mercury, and almost half the diameter of the Earth itself. It is the Solar System's largest moon. It is a moon, though, in slumber. It has a surface of ice mountains, often with long intersecting ridges. There are darker and light regions, all of them ancient. There are craters, but the older ones have not been left exactly as they were formed. Once upon a time, Ganymede did not sleep, but had an active surface. The ice moved. [ABSTRACT FROM AUTHOR]

Comets come closer to the Sun to die. The Sun blasts away at their icy cores; it diminishes them little by little, and sometimes, in the end, it pulls them in and consumes them. [ABSTRACT FROM AUTHOR]

If a worthy committee were to design a moon, then some decisions would be relatively straightforward. Yes, it should be round, since that is, after all, the default shape for moons, at least the larger ones. And there should be craters. Moons are supposed to have craters. [ABSTRACT FROM AUTHOR]

It's a long, long story; 75,000 years long. It's the tale of the orbit of comet Kohoutek around the Sun, a journey of a thousand lifetimes. Its visit to us here in the inner Solar System in the mid-1970s led members of one cult in the USA, The Children of God, to flee to communes around the world, convinced by their leader, David Berg, that doomsday was coming to America. But that's another story - a short one, but intriguing nonetheless in its revelations about the many-faceted relationship between the Cosmos and its people. [ABSTRACT FROM AUTHOR]

Mars is a dead planet, a desert ball. It is not quite certain that it has always been so, but if there is life there now it is being very coy - various missions including the Mars Rovers have found no sign. Perhaps one day humans will land there, with sealed spacesuits standing in for the Earth's protecting atmosphere. For now, Mars spins and tumbles around the Sun, carrying nothing but its red dust blown by thin winds that nobody will ever feel on their skin. The planet is closer than the Earth to the main asteroid belt, and there are plenty of asteroids that cross its pathway. Collisions are inevitable. So beneath the blowing sands of its deserts there are craters. [ABSTRACT FROM AUTHOR]

An arc of Saturn shines brightly in the sunlight, against the blackness of space beyond it to the right, and its own night time on the left. Night time on Saturn is not always quite like the Earth's hours of darkness. On Earth we sometimes have the Moon, as well as the light with which we ourselves flood our planet to prevent our dark side from being truly dark. Saturn has her rings. [ABSTRACT FROM AUTHOR]

The Hubble Space Telescope is known for its high-resolution images of distant objects that are far outside the Sun's small family of planets. Those distant galaxies are not just a long way away; they are also very large. Hubble can produce images of our own neighborhood, as here, in which the objects are much smaller as well as much nearer. Neptune has a diameter that is much less than a millionth of the distance across the whole Solar System, which itself is tiny compared to the distance to the nearest star, and tiny again compared with a galaxy. [ABSTRACT FROM AUTHOR]

Asteroid Ida is a little more than 50 kilometers long and 20 kilometers wide - bigger than a mountain, smaller than a mountain range. Its gravity is not strong enough to pull irregularities into itself as happens for the Earth, where the attraction of matter to matter will not tolerate much departure from the spherical. Here, mountains sink under their own weight and the peaks of the Rockies and the Himalayas cannot be higher than they are, but the shape of the little asteroid is not so constrained. [ABSTRACT FROM AUTHOR]