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Interesting Solar System worlds

The 18 Most Interesting Worlds in our Solar System

posted by Mr. Black Oct 14, 2009

The Solar System. Our planetary network in the cosmos. A region becoming more fascinating everyday. And even more mysterious. In this article we look at not only planets, but also moons and dwarf planets, which together make up the 18 most interesting worlds in the Solar System.



Ceres #18

This interesting world is located between Mars and Jupiter. First we called it a planet. Then an asteroid. Today, Ceres is classified as a dwarf planet. What is most fascinating about Ceres, is that unlike all other dwarf planets, it exists not in the far reaches beyond Neptune: but within the inner Solar System...

Ceres lives in the Asteroid belt, a region that lies in between Mars and Jupiter; consisting of the tens of thousands of asteroids. At 950 km in diameter, Ceres is in fact the largest of these objects.

The picture above, the highest detail image available of Ceres, was taken in 2004 by Hubble. It reveals a blue glow strikingly similar to the space imagery of Earth. In fact, there are indications that Ceres may have a relatively warm atmosphere. This may account for the Earth like blue glow - and could even make Ceres the most Earth like world in the Solar System.

What's more - is that Ceres potentially has more fresh water than on Earth. Computer models suggest this world has an interior made up of dense material, with the lighter particles near the surface. This could mean Ceres has a rocky core padded by a thick mantle of water ice. If this mantle composition consists of at least 25 percent water, Ceres would have more fresh water than Earth.

In addition to the obvious potential for life, an abundant water on Ceres supply could make it a key outpost for future space missions. A theoretical manned mission to Jupiter's moon system, would involve a strategic water fill up at Ceres.

We'll find out more on Ceres when NASA's Dawn mission arrives to Ceres in February 2015. Launched in September 2007, Dawn will be the first spacecraft to visit Ceres.

Class: Asteroid Belt
Diameter: 950 km
Probability of Life: High



Io #17

The most volcanically active location in the Solar System is at Jupiter's moon Io. The surface of this hellish world is scabbed with the presence of over 400 active volcanoes. Massive eruptions of liquid sulfur fuel the sulfur dioxide packed atmosphere. Enormous fountains called "plumes" which have been recorded at over 300 km high are like geysers on Earth, but instead of boiling water it's hot gas escaping from Io's interior. The plumes can be strikingly impressive, because as the gas expands into space, it cools and freezes into something like snowflakes - creating some spectacular imagery.

Data from Galileo indicates that Io has a core of iron. Although, as more data has been collected astronomers are starting to think the interior of Io might be completely molten. Gravitational forces exerted on Io by Jupiter and the other large Jupiter moons raise tidal bulges in Io's solid crust as much as 30 meters high. This flexing action makes Io's interior molten hot. And as a result, the moon has hundreds of volcanoes. Io is in a constant state of eruption.

Class: Jupiter's moon
Diameter: 3,642 km
Probability of Life: Low



Miranda #16

The small moon of Uranus, Miranda, has a bizarre surface that baffles scientists.

Almost nothing was known about Miranda until the Voyager 2 probe which observations of Uranus and its moon system in 1986. The first images sent back were in many ways shocking.

The moon has a rigid, sawtooth pattern of ridges and grooves cut across the surface along with a huge mountain range and towering cliffs. A Geologist from the U.S. Geological Survey, Larry Soderblom, called Miranda "a bizarre hybrid of the valleys and layered deposits on Mars, combined with the grooved terrain on Ganymede, and the compressional faults of Mercury."

These extreme surface features are in contrast to what is typically assumed about small bodies. Nothing like Mirandas surface have ever been seen before. The current running theory to explain this strange world's uninviting terrain is that a violent collision smashed apart pieces of the moon. These icy & rocky chunks later fell back together. Yet according to Bob Pappalarado of the University of Colorado, "The blown-apart story is over-simplified." And that there are too many unanswered questions to call Miranda's case closed.

One provocative theory of Miranda's formation comes from controversial researcher Zecharia Sitchin. Based on his study of ancient Sumerian tablets Sitchin believes that Miranda was once a moon of another, yet to be discovered, planet in our Solar System called Nibiru. "As a result of this close encounter between Nibiru and Uranus, one of Nibiru's moons, Miranda, was captured by and became a moon of Uranus as Nibiru and Uranus pulled at each other," says Sitchin. Regardless, Miranda is a mysterious world that has us craving for further exploration.

Class: Moon of Uranus
Diameter: 480 km
Probability of Life: Low



Uranus #15

The only world in the Solar System that spins "up and down" and not side to side is Uranus. The planet is essentially on its side in relation to the sun. Why exactly does Uranus spin this way is still not fully understood. One hypothesis is that Uranus was "knocked over" by a massive planetary impact.

The extreme axial tilt has striking influence on the magnetic field of Uranus. It is tilted 60 degrees from the planet's axis of rotation. And the magnetic tail of Uranus is twisted by the planet's rotation into a long corkscrew shape behind the planet. The source of the magnetic field is unknown.

While Uranus is the third largest planet in the Solar System, it is significantly smaller than Jupiter and Saturn. It is theorized that Uranus has a rocky core, padded by a mantle of liquid water, methane, and ammonia all trapped in an atmosphere of hydrogen and helium. Like the other giants of the Solar System, Uranus also has a ring system.

In 1986 Voyager 2 made a historic reconnaissance of Uranus and its satellites. And has since been the only close up encounter with this big blue world. No other visits are planned.

Class: Ice Giant
Diameter: 51, 500 km
Probability of Life: ?



Haumea #14

The fastest spinning object in the Solar System is Haumea, a dwarf planet beyond Neptune. This speed along with an extreme elongation makes Haumea unique among the known trans-Neptunian objects. The egg like shape is believed to be caused by the rapid rotation.

What makes this world mysterious is the "fresh ice" that covers the surface. The surface is as bright as snow, suggesting a large presence of pure crystalline water ice. This is in contrast to a world such as Pluto, where its surface has been darkened to a reddish brown after receiving a bombardment of cosmic rays and energy particles from the sun. In addition, the structure of crystalline ice is unstable under these conditions. It seems that the only plausible scenario is that Haumea has had some type of recent activity that has helped form pure crystalline ice.

Most recently, a large red area was discovered on the dwarf planet that appears to be richer in minerals and organic compounds than the surrounding icy surface. This origin of the spot is unknown. Given the bizarre dynamics of Haumea the red area could be anything - maybe even a migration of microbial life to the surface.

Class: Dwarf Planet
Diameter: 1,400 km
Probability of Life: Medium



Ganymede #13

The largest moon in the Solar System, larger than even the planet Mercury, is also the only moon to possess it's own magnetosphere. Which is embedded within Jupiter's magnetosphere.

The surface of Ganymede consists of rocks, clay, ice, and other organic materials. The world seems to have active tectonic activity, with valleys and ridges.

Beneath the crust, may exist insect life forms . Or sludgy like creatures sticking to walls of subterranean caverns. And even further within the crust of Ganymede, about 200 km deep, exists a saltwater ocean. NASA detected this ocean in 2000 as the Galileo spacecraft observed Jupiter and its moons, before later crashing itself into Jupiter. A future mission to Ganymede may invove setting up a base on the surface with the drilling capacity to tunnel into this subterranean ocean.

Class: Moon of Jupiter
Diameter: 5,262 km
Probability of Life: High



Triton #12

The largest moon of Neptune, Triton, is a snowy world with active Ice geysers. It is the only major moon in the Solar System with a retrograde orbit (an orbit in the opposite direction to its planet's rotation). Because of this retrograde orbit and its Plutonian like composition it is believed that Triton was a distant Dwarf Planet captured from the Kuiper belt.

A crust of frozen nitrogen and its icy mantle is believed to pad a core of rock and metal. The surface is smooth and pocked along with intricate, mysterious cryovolcanic and tectonic terrains. The world is one of the few moons in the Solar System to be geologically active. Evidenced by the nitrogen ice geysers and tectonic shifting of the land.

Triton exhibits a volcanic process similar to that of Earth, but instead of molten rock here, it is a slushy water-ammonia lava mixture that flows from ice volcanoes. At least two of these "cryovolcanoes" were observed from the Voyager 2 flyby. This cryovolcanic activity indicates a world that is extremely young in the context of the Solar System.

Class: Moon of Neptune
Diameter: 2,700 km
Probability of Life: Medium


Pluto and Charon

Charon #11

Only a decade ago, Pluto was considered eighth planet in the Solar System, one ahead of Neptune - the ninth planet at the time. This is because Pluto "crossed" Neptune's orbit on January 21, 1979 - temporarily putting it closer to the sun.

In 1999 Pluto moved back into the eighth position. And eventually in 2006, the International Astronomical Union (IAU) demoted Pluto to Dwarf Planet status.

This all makes the Pluto story very interesting but what is perhaps most interesting of all is the neighboring world Charon. Long to be considered a moon of Pluto, Charon may one day to be classified as a Dwarf planet. This is because the Pluto / Charon relationship is unlike any other moon system observed. Charon does not actually orbit Pluto, but rather the two icy worlds orbit a shared region of space between them (known as a barycenter). Much like a dual star system, Pluto and Charon form a dual dwarf planet configuration.

But why is Charon more interesting than Pluto? At about half the mass of Pluto, it certainly isn't because of its size. It is in fact the hunt for life that brings Charon under closer investigation. Of course, here in the deepest, blackest regions of our Solar System - it is the last place you would expect to find life - but recent detections of active ice geysers on Charon have some scientists very curious.

In 2015 the New Horizons spacecraft will arrive as part of NASA's mission to study Pluto and Charon. This craft has already flew by Jupiter and is well on it's way to the outer reaches of the Solar System. To visit Pluto & Charon for the first time.

Class: Moon of Pluto
Diameter: 1,207 km
Probability of Life: Medium



Saturn #10

Consisting of mostly gas, Saturn is the only planet of the Solar System that is less dense than water. Although you could fit about 833 Earths inside the sphere of Saturn, the mass of Saturn is only 95 Earth masses.

What's inside of this giant floaty cloud world? While there is no direct information about Saturn's internal structure - the interior is thought to contain a dense, rocky core. With a layer of liquid metallic hydrogen. Followed by a layer of liquid hydrogen and helium, and in the outermost 1000 km a gaseous atmosphere.

Saturn Hexagon

Like Jupiter's Red Spot, Saturn has it's own mysterious storm feature: the hexagonal cloud. The structure exists on Saturn's north pole. With each side of the hexagon being about 13, 800 km long. It's a polygonal shape of truly massive proportions never before observed in nature. What causes the hexagonal cloud is unknown.

With at least 61 moons and an impressive ring system, Saturn is certainly a close match to Jupiter's system for the most interesting region of the Solar System. Currently, the Cassini space probe is within Saturn's orbit in its first mission extension.

Class: Gas Giant
Diameter: 120,536 km
Probability of Life: Medium


Mars' surface

Mars #9

Ancient oceans and volcanoes. Valleys, deserts, and mountains. Mars is an interesting and equally mysterious world.

Mars has two macro geophysical features that are bigger than anywhere else in the Solar System. This is the Olympos Mons, the highest known mountain. And Valles Marineris, the largest canyon.

With water confirmed on Mars, the potential for life is undeniable. Many argue that NASA detected life on Mars as early as 1976 during the first Viking mission. Nevertheless, later missions: Spirit & Opportunity proved that ancient oceans were once prevalent on Mars. And finally on July 31, 2008 the Phoenix Lander confirmed the presence of water ice.

Although there are no visible signs of life on the surface, given the fact that Mars was once very Earth like - it isn't a stretch to assume that simple organisms may be hiding just below the soil layer of Mars - or within the deeper regions of Valles Marineris, or miles below in underground caves. Since Mars is so close, missions to explore these regions could very well occur in our lifetime.

Class: Inner Planet
Diameter: 6,792 km
Probability of Life: Very High


Europa's surface

Enceladus #8

Ice crystal geysers on Enceladus' surface shoot powerful bursts of water vapor into the atmosphere. These water vapor geysers are proof of significant geological activity. Combined with an abundant with liquid water, Enceladus (pronounced "En-sell-a-dus ") is a priority destination in the search for life.

But the question of fresh water within Saturn's moon Enceladus is not yet answered. The water vapor spewing from the surface was first observed in 2008. And indeed, evidence from the Cassini probe points to a possible global liquid ocean beneath the frozen surface. More recently, in August 2009, scientists announced that analysis of vapor spewing from Enceladus contain unusually high levels of salt. In addition, Cassini found traces of organic compounds such as carbonates. This in combination with visible tectonics on the surface is strong evidence of a sub surface ocean.

If an ocean does exist beneath Enceladus, it would mean there must be an internal heat source. And indeed it is believed that tidal heating, the same phenomena that creates internal heat for Jupiter's similar icy ocean world Europa, is largely responsible for the warmth on Enceladus.

Class: Moon of Saturn
Diameter: 505 km
Probability of Life: High


The Moon

Jupiter #7

The most massive planetary body in the Solar System is two and a half times the mass of all other planets in our Solar System combined.

Jupiter and its 63 moons, one of which is larger than Mercury (Ganymede), makes up a very dynamic region of the Solar System. In many ways, Jupiter is like a star with it's own Solar System. And in fact, Jupiter radiates heat like a star. Many astronomers consider Jupiter to be a "failed star" because if Jupiter had just 75 times more mass it would create fusion and become a star.

Jupiter's contains a highly dynamic environment. A storm, the Great Red Spot, has lasted as long as 300 years. And Jupiter has lightning that can be up to a thousand times as powerful as here on Earth. Combined with the presence of this lightning and chemical compounds it has been demonstrated that organic compounds can form. Such as as amino acids that are known to be building blocks of life. There is a high probability that at the very least, simple micro organisms, exist within Jupiter. With perhaps even strange bird like creatures who flow with the upper atmosphere. And fish like creatures who swim deep within.

Class: Gas Giant
Diameter: 142,984 km
Probability of Life: High


Titan #6

Considered by many Astronomers to be the most Earth like world ever discovered, Titan is the only moon to in the Solar System known to possess a dense atmosphere. It is also the only world other than Earth for which clear evidence of liquid lakes have been found.

Over 1 billion kilometers from our planet, Saturn's largest moon: Titan - has an atmosphere that resembles early Earth. Yet for decades the surface of Titan remained a mystery. Shrouded in a thick haze, the early Voyager flybys produced just teasers of the creamy orange world. To reveal the true nature of Titan first hand, scientists knew they had to go in for a much closer look.

On January 14, 2005. After a 7 year track across the Solar System - the 400 million pound space probe, the Huygens lander, was released by the Cassini orbiter - and it began it's firey ascent into Titan's atmosphere.

Huygens was designed to see, sniff, touch, taste and even listen to the mysterious moon. During it's two and a quarter hour descent, Huygens would beam radio signal back to the orbiting Cassini, which in turn sent it back to Earth - revealing the surface beneath.

Titan Rivers

On this descent, the Huygens probe photographed a network of dark "rivers" running down to a dark plain. After landing, Huygens photographed a dark plain covered in small rocks and pebbles, composed of water ice. The surface was darker than originally expected, consisting of a mixture of water and hydrocarbon ice.

Leader of the Cassini radar team, Stephen D. Wall, said, "It's comforting to find that Titan is so amazingly Earth-like in so many ways, but it's fascinating to find so much that's a mystery. We're seeing dunes of ice grains like deserts... and drainage channels that look for all the world like the Amazon, and volcanoes and impact craters and lakes." Titan has now been shown to feature even beaches and lakes. "That moon is amazingly Earth-like," he said.

Titan's lake

One of the lakes on Titan is larger than any of the Great Lakes in North America. However, instead of water - the lakes are believed to be made up of mostly liquid methane or ethane. With such large bodies of liquid on Titan's surface, it is a compelling destination in the search for life. On Earth, life has been detected in the most extreme conditions: abundant in boiling hot, chemically rich hypothermal vents deep in the ocean. It would be a surprise if Titan is void of life.

Class: Moon of Saturn
Diameter: 5,150 km
Probability of Life: High



Venus #5

Once a rich landscape with Earth like oceans, the landscape of Venus is now considered to be very hot and desolate. With any oceans now evaporated into its dense atmosphere. Yet, even with this boiling hot atmosphere it has been postulated that microbial life could exist in the upper cloud layer. What's more, is that since Venus is in such close proximity to Earth, solar winds could theoretically transport microbial Venus life to Earth. Indeed, if Venus was once a tropical paradise - it is even a possibility that life on Earth could have originated on Venus.

Another possibility for life on Venus is underground. If oceans and life once existed on the surface, it would be expected that some ground dwelling insects and organisms would be able to survive under the insulation of the surface layer.

Aside from the obvious prospect of microbial life, the planet itself is a strange world. Venus has the slowest rotation of any planet in the Solar System. A day on Venus is 243 Earth days long. In fact, its year (225 Earth days) is shorter than its day!

Class: Inner Planet
Diameter: 12,103 km
Probability of Life: Medium


The Moon

The Moon #4

Despite being the closest world to our own, the Moon is quite possibly the strangest object in our Solar System. Many assume the Moon is just an old boring, clump of gray rocks. But the truth, is that our moon is quite a shocking mystery.

For starters, no one knows how the moon was created. Despite popular theories, there is no definitive explanation as to how or where our moon came from. This is startling to ponder considering we humans have set our own feet on the surface and have had the better part of 50 years to analyze lunar rock, piles of data obtained from Apollo missions, and dozens of satellite observers. Why no answer ? The problem is that with more data, comes more questions. Turns out our moon is more complicated than anyone ever expected.

Rocks found on the moon that are older than Earth. The mineral distribution is totally unlike Earth (and most other planets). The absurdly perfect, stationary circular orbit. And the profoundly rare alignment which creates a solar eclipse.

Most recently, in September 2009, a discovery was announced about widespread, yet small amounts of water distributed on the surface of the moon.

Planetary geologist Carle Pieters who led one of the studies said, "Widespread water has been detected on the surface of the moon." He continued, "The rest is history now. It is completely conclusive."

Class: Moon of Earth
Diameter: 3,500 km
Probability of Life: ?


Europa's surface

Europa #3

The best chance for alien life within our Solar System is within the icy crust of Jupiter's moon: Europa. Of Jupiter's 63 moons, Europa is perhaps the most beautiful. Its atmosphere is composed mostly of oxygen. And the exciting part: this world eatures a sub glacial ocean.

Europa is among the most mysterious worlds of the Solar System. Upon initial examination, scientists found that something very weird was going on here. Europa gets hit with just as much space debris as the other large Jupiter moons. And it should have a ton of impact craters to show for it. But that's not the case. In fact, Europa is one of the smoothest bodies in the Solar System. That wouldn't otherwise make any sense unless: it's surface is actually made of ice.

Look at any Europa image and what you are seeing is not solid land. It's world covered in ice that's constantly being replenished and erasing all the scars from meteor collisions. So where does that ice get replenished from?

There's an ocean under there. Scientists have since detected a global ocean swirling beneath the frozen crust. And they think the ocean is warm enough to support life. For that reason, Europa gives us the best chances of finding life outside our own planet.

Class: Jupiter's moon
Diameter: 3,100 km
Probability of Life: Very High



Iapetus #2

A large moon orbiting the planet Saturn has a striking feature that defies what we know about worlds. Images sent from NASA's Cassini probe have revealed a gigantic equilateral "ridge" which wrap around the equator of Iapetus.

The equilateral ridge is clearly visible from space. And at 20 km high the ridge is so big these proportions are not seen anywhere else in the Solar System. To put this into context: the tallest mountain on Earth, Mount Everest, peaks at about 9 km tall.The Iapetus equilateral ridge is more than double that, yet this world is about 9 times smaller than Earth. And the peak of Mount Everest certainly does not wrap around the entire equator of Earth. On Iapetus, if you lived anywhere near the equator half of the sky would be consumed by this monstrosity.

Iapetus anomaly

The ridge's formation is unknown. During Cassini's Iapetus fly by that led to the discovery of the ridge, NASA was quoted saying on their website, "startling surface features" are fueling heated scientific discussions about their origin. NASA went on to say that, "No other moon in the Solar System has such a striking geological feature..."

This formation is so bizarre, so mathematically defying, that extraterrestrial origin has not ruled out.

IapetusIapetus has another striking feature. The moon is "two faced". In what is another feature unique only to Iapetus - this moon has a snowy bright white side and a darker brown colored side. Forming a distinct contrast. Half of Iapetus appears as dark as asphalt. And the other half appears as bright as snow (the snowy side featured in the photo to the left).

Recently, the primary cause of this effect was discovered. Saturn has another, newly discovered colossal ring that extends far beyond the traditional ring system as commonly photographed. "The particles of this massive ring smack Iapetus like bugs on a windshield." said Anne Verbiscer from the University of Virginia.

A third mysterious feature of Iapetus is it's rigid hexagonal shape. Almost as if the internal structure of the moon has corners and edges.

Further exploration of Iapetus will be exciting. To discover more about its mysteries. And for beautiful photos of Saturn. Indeed, the view of Saturn from Iapetus is the best of any other world in the Solar System. Unlike the other Saturn moons, the orbit of Iapetus has an unusually high inclination. Other moons sit on Saturn's equilateral plane so you would only be able to see Saturn's rings on edge; making them difficult to observe. On Iapetus, because of the inclined orbit, you would be able to see Saturn's rings in their full glory. The computer simulated view below shows Saturn as seen from Iapetus.

Class: Saturn's moon
Diameter: 1,430 km
Probability of Life: ?



Neptune #1

Neptune has the strongest sustained winds of any planet in the Solar System. With recorded wind speeds as high as 2100 km/h.

It is also one of the coldest places in the Solar System, with temperatures at its cloud tops approaching -218 C. However, just below this cloud layer (the thermosphere) the temperature reaches an astoundingly high of 476 C. Since the planet is too far from the Sun, this heat must be generated locally.

Neptune, along with Uranus, are considered "ice giants." The name is appropriate since they do have large quantities of water ice mixed in with other gases. There's very little water at the cloud tops, but the percentage of water increases as you descend towards the heavier core. There may even be a a layer on Neptune with enough pressure and temperature for liquid water to form into vast oceans. Perhaps explaining why Neptune is blue.

NASA's consensus about Jupiter, Saturn, Uranus and Neptune all being large gas giants is not a fully adequate explanation for many. Some argue that, while these worlds do contain heavy amounts of gas, violent storm conditions, and tremendous energy - that there may be a larger, more diverse, and perhaps habitable rocky surfaces that exist at depths much closer to the surface than what our current mainstream science assumes.

Neptune is the number one mystery world because we just don't know what's inside. We have never been there. And other than a briefly flyby during Voyager 2, there has never been a space probe sent to investigate Neptune. Vast oceans of aquatic sea life. Tropical islands of lush landscape, shielded and insulated by its thick stormy cloud layers. And forest like creatures who dwell deep within subterranean caverns. We just don't know. Until we go there, Neptune is just as mysterious as any other of the interesting worlds in our Solar System.

Class: Ice Giant
Diameter: 49,528 km
Probability of Life: ?



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