Planet Jupiter: Facts About Its Size, Moons and Red Spot Planet Jupiter: Facts About Its Size, Moons and Red Spot By Charles Q. Choi, Space.com Contributor | November 14, 2014 12:59am ET MORE This photo of Jupiter was taken on Sept. 20, 2010 when Jupiter made its closest approach to Earth since 1963. (Uranus [insert] was visible through telescopes near Jupiter.) Credit: Jimmy Eubanks Jupiter is the largest planet in the solar system. Fittingly, it was named after the king of the gods in Roman mythology. In a similar manner, the ancient Greeks named the planet after Zeus, the king of the Greek pantheon. Jupiter helped revolutionize the way we saw the universe and ourselves in 1610, when Galileo discovered Jupiter's four large moons — Io, Europa, Ganymede and Callisto, now known as the Galilean moons. This was the first time celestial bodies were seen circling an object other than Earth, major support of the Copernican view that Earth was not the center of the universe.

Physical characteristics Jupiter is the most massive planet in our solar system , more than twice as massive as all the other planets combined, and had it been about 80 times more massive, it would have actually become a star instead of a planet. Its atmosphere resembles that of the sun, made up mostly of hydrogen and helium, and with four large moons and many smaller moons in orbit around it, Jupiter by itself forms a kind of miniature solar system. All told, the immense volume of Jupiter could hold more than 1,300 Earths. The colorful bands of Jupiter are arranged in dark belts and light zones created by strong east-west winds in the planet's upper atmosphere traveling more than 400 mph (640 kph). The white clouds in the zones are made of crystals of frozen ammonia, while darker clouds of other chemicals are found in the belts. At the deepest visible levels are blue clouds. Far from being static, the stripes of clouds change over time . Inside the atmosphere, diamond rain may fill the skies. The most extraordinary feature on Jupiter is undoubtedly the Great Red Spot , a giant hurricane-like storm seen for more than 300 years.

At its widest, the Great Red Spot is three times the diameter of the Earth, and its edge spins counterclockwise around its center at a speed of about 225 mph (360 kph). The color of the storm, which usually varies from brick red to slightly brown, may come from small amounts of sulfur and phosphorus in the ammonia crystals in Jupiter's clouds. The spot grows and shrinks over time, and every now and again, seems to fade entirely. Jupiter's gargantuan magnetic field is the strongest of all the planets in the solar system at nearly 20,000 times the strength of Earth's. It traps electrically charged particles in an intense belt of electrons and other electrically charged particles that regularly blasts the planet's moons and rings with a level of radiation more than 1,000 times the lethal level for a human, damaging even heavily shielded spacecraft such as NASA's Galileo probe.

The magnetosphere of Jupiter, which is composed of these fields and particles, swells out some 600,000 to 2 million miles (1 million to 3 million km) toward the sun and tapers to a tail extending more than 600 million miles (1 billion km) behind Jupiter. Jupiter spins faster than any other planet, taking a little under 10 hours to complete a turn on its axis, compared with 24 hours for Earth. This rapid spin makes Jupiter bulge at the equator and flatten at the poles, making the planet about 7 percent wider at the equator than at the poles. Jupiter broadcasts radio waves strong enough to detect on Earth. These come in two forms — strong bursts that occur when Io, the closest of Jupiter's large moons, passes through certain regions of Jupiter's magnetic field, and continuous radiation from Jupiter's surface and high-energy particles in its radiation belts. These radio waves could help scientists to probe the oceans on its moons.

Composition & structure Atmospheric composition (by volume): 89.8 percent molecular hydrogen, 10.2 percent helium, minor amounts of methane, ammonia, hydrogen deuteride, ethane, water, ammonia ice aerosols, water ice aerosols, ammonia hydrosulfide aerosols Magnetic field: Nearly 20,000 times stronger than Earth's Chemical composition: Jupiter has a dense core of uncertain composition , surrounded by a helium-rich layer of fluid metallic hydrogen, wrapped up in an atmosphere primarily made of molecular hydrogen. Internal structure: A core less than 10 times Earth's mass surrounded by a layer of fluid metallic hydrogen extending out to 80 to 90 percent of the diameter of the planet, enclosed in an atmosphere mostly made of gaseous and liquid hydrogen. Orbit & rotation Average distance from the sun : 483,682,810 miles (778,412,020 km). By comparison: 5.203 times that of Earth Perihelion (closest approach to the sun): 460,276,100 miles (740,742,600 km).

By comparison: 5.036 times that of Earth Aphelion (farthest distance from the sun): 507,089,500 miles (816,081,400 km). By comparison: 5.366 times that of Earth (Source: NASA .) Jupiter's moons Jupiter has at least 63 moons , which are often named after the Roman god's many lovers. The four largest moons of Jupiter, now called Io, Europa, Ganymede, and Callisto, were discovered by Galileo Galilei himself, and are appropriately known today as the Galilean satellites. Ganymede is the largest moon in our solar system, larger even than Mercury and Pluto. It is also the only moon known to have its own magnetic field. The moon has at least one thick ocean between layers of ice, although it may contain several layers of both materials. Io is the most volcanically active body in our solar system. The sulfur its volcanoes spew out gives Io a blotted yellow-orange appearance that is often compared to a pepperoni pizza.

As Io orbits Jupiter, the planet's immense gravity causes 'tides' in Io's solid surface that rise 300 feet (100 meters) high, generating enough heat for volcanic activity. The frozen crust of Europa is made up mostly of water ice, and it may hide a liquid ocean holding twice as much water as Earth does. Icy oceans may also exist beneath the crusts of Callisto and Ganymede. Some of this liquid spouts from the surface in newly spotted sporadic plumes at the southern pole. Its potential to host life caused NASA to request funding for a mission to explore Europa . Callisto has the lowest reflectivity, or albedo, of the four Galilean moons. This suggests that its surface may be composed of dark, colorless rock. Jupiter's rings Jupiter's three rings came as a surprise when NASA's Voyager 1 spacecraft discovered them around the planet's equator in 1979. Each are much fainter than Saturn's rings. The main ring is flattened. It is about 20 miles (30 km) thick and more than 4,000 miles (6,400 km) wide.

The inner cloud-like ring, called the halo, is roughly 12,000 miles (20,000 km) thick. The halo extends halfway from the main ring down to the planet's cloud tops and expands by interaction with Jupiter's magnetic field. Both the main ring and halo are composed of small, dark particles. The third ring, known as the gossamer ring because of its transparency, is actually three rings of microscopic debris from three of Jupiter's moons, Amalthea, Thebe and Adrastea. It is probably made up of dust particles less than 10 microns in diameter, about the same size of the particles found in cigarette smoke, and extends to an outer edge of about 80,000 miles (129,000 km) from the center of the planet and inward to about 18,600 miles (30,000 km). Ripples in the rings of both Jupiter and Saturn may be signs of impacts from comets and asteroids.

Research & exploration Seven missions have flown by Jupiter — Pioneer 10 , Pioneer 11 , Voyager 1 , Voyager 2 , Ulysses, Cassini and New Horizons — while another, NASA's Galileo, actually orbited the planet. Pioneer 10 revealed how dangerous Jupiter's radiation belt is, while Pioneer 11 provided data on the Great Red Spot and close-up pictures of its polar region. Voyager 1 and 2 helped astronomers create the first detailed maps of the Galilean satellites, discovered Jupiter's rings, revealed sulfur volcanoes on Io, and saw lightning in Jupiter's clouds. Ulysses discovered the solar wind has a much greater impact on Jupiter's magnetosphere than before suggested. New Horizons took close-up pictures of Jupiter and its largest moons. In 1995, Galileo sent a probe plunging towards Jupiter, making the first direct measurements of its atmosphere and measuring the amount of water and other chemicals there. When Galileo ran low on fuel, the craft was intentionally crashed into Jupiter's atmosphere to avoid any risk of it slamming into and contaminating Europa, which might have an ocean below its surface capable of supporting life.

Another spacecraft, named Juno , is heading toward Jupiter and will reach the planet in 2016. It will study Jupiter from a polar orbit to figure out how it and the rest of the solar system formed, which could shed light on how alien planetary systems might have developed. Jupiter's gravitational impact on the solar system As the most massive body in the solar system after the sun, the pull of Jupiter's gravity has helped shape the fate of our system. It may have violently hurled Neptune and Uranus outward , according to calculations published in the journal Nature. Jupiter, along with Saturn, may have slung a barrage of debris toward the inner planets early in the system's history, according to an article in Science magazine. It may even nowadays help keep asteroids from bombarding Earth, and recent events certainly have shown that it can absorb potentially deadly impacts . Currently, Jupiter's gravitational field influences numerous asteroids that have clustered into the regions preceding and following Jupiter in its orbit around the sun. These are known as the Trojan asteroids, after three large asteroids there, Agamemnon, Achilles and Hector, names drawn from the Iliad, Homer's epic about the Trojan War.

Possibility of life on Jupiter If one were to dive into Jupiter's atmosphere , one would discover it to grow warmer with depth, reaching room temperature, or 70 degrees F (21 degrees C), at an altitude where the atmospheric pressure is about 10 times as great as it is on Earth. Scientists have conjectured that if Jupiter has any form of life, it might dwell at this level, and would have to be airborne. However, researchers have found no evidence for life on Jupiter. Additional reporting by Nola Taylor Redd, Space.com Contributor Explore the solar system Earth Was Created for Life | The Institute for Creation Research Earth Was Created for Life Evidence for Creation › Evidence from Science › Evidence from the Physical Sciences › The Earth Was Uniquely Created » Next Our solar system is filled with amazing planets, but none are perfect for life except the earth. Mercury is the closest planet to the sun. It gets very hot and very cold. It has a very slow spin. The side facing the sun is heated to 800 (F) while the side away from the sun is cooled to –298 degrees (F). Venus is hotter than Mercury, yet farther away from the sun.

Venus has an atmosphere 90 times thicker than earth's. Heat is trapped in the clouds and heats the entire planet to 931 degrees (F). Mars is similar to earth in many ways. A day on Mars is 24.7 hours. It is tilted 25 degrees, just two more degrees than earth. At its warmest, it can get to be a comfortable 67 degrees (F). It has two small moons. But Mars is smaller than earth. The gravity on Mars is only a third of the earth’s. Without enough gravity, Mars is unable to hold a larger atmosphere. What atmosphere it has is made of the gases we cannot breathe. Without much of an atmosphere, many meteoroids hit Mars. It also gets very cold at night. Jupiter is the largest planet in our solar system. It is ten times smaller than the sun and ten times larger than the earth. Jupiter spins faster than any other planet, with a day of 9 hours and 55.5 minutes. Its fast spin causes tremendous storms. The big red spot on Jupiter is a huge hurricane. Saturn is the second-largest planet in our solar system and has the largest set of rings.

It is almost twice as far away from the sun as Jupiter is. Saturn is a gas giant. As one descends into the atmosphere, the pressure, temperature, and gravity greatly increase. The core of the planet is boiling hot and radiates more heat out into space than it receives from the sun. Uranus is tilted on its side with its axis pointed at the sun. If the earth's axis was pointed at the sun, one hemisphere would always be boiling hot and the other would be freezing cold. Uranus is four times as far from the sun as Jupiter and twice as far from the sun as Saturn. Neptune is the farthest gas giant from the sun. It is almost four times larger than the earth. Its strong gravity traps harmful gases in its atmosphere. The utter lifelessness of other planets in our solar system illustrates the fact that earth is unique and specially created for life. Jupiter & Saturn | Cool Cosmos Jupiter & Saturn The Big Bang Jupiter & Saturn Jupiter and Saturn are the biggest planets in our Solar System. Infrared observations of these gas giants have mapped weather patterns, observed asteroids and comets crashing through their atmospheres, and discovered a huge new ring around Saturn.

Jupiter Jupiter, the King of the Planets, is a gas giant, which means that it's made mostly of gases like hydrogen and helium, and that it doesn't have a solid surface in the way that rocky planets like Earth do. With a temperature of 130 K (-140 C, -230 F), it's so cold that it gives off most of its energy in the infrared. In fact, Jupiter gives off almost twice as much heat as it receives from the Sun. It's able to do this because it has its own internal heat source, powered by the slow gravitational collapse that started when the planet first formed. Astronomers estimate that Jupiter is currently shrinking by almost 2 cm per year! Jupiter's Atmosphere Heat from the interior of Jupiter causes circulation patterns in the atmosphere, with warm gas rising and cooling, before sinking back into the depths of the planet. This process is called convection, and it causes the different colored bands in Jupiter's atmosphere. The light colored bands, called "zones," are the rising areas, while the dark colored regions, or "belts," are the sinking gas.

The different colors come from their different chemical compositions; astronomers think that the darker colored belts contain hydrocarbons - molecules that are made from hydrogen, carbon, and oxygen, which turn a darker color when exposed to the Sun's ultraviolet light. The rising zones, meanwhile, soar high into the atmosphere, and contain clouds of ammonia ice crystals that reflect sunlight, and block the view of the darker layers below, just like clouds here on Earth. Atmosphere in the Infrared If we look in the infrared, we can see that the ammonia ice clouds that shine so brightly in visible light look darker in the infrared, showing that they are cooler. The clouds don't just block our view of the lower layers, they also block the heat that's being generated from deeper in the planet, making those areas look colder than the belts. The sinking gas in the belts, on the other hand, forms no cloud cover, and so we see deep into Jupiter's atmosphere where it is far warmer than at the tops of the clouds. The belts glow brightly in the infrared, as they pump the heat from the planet's interior out into the Universe. Infrared observations can also tell us a lot about the composition of the clouds.

Methane, one of the main components of Jupiter's atmosphere, heavily absorbs some wavelengths of infrared light. If we look in those specific wavelengths, we find that areas containing a lot of methane look very dark compared to the surrounding areas. This method can be used by astronomers to map the location and movement of different gases that make up the atmosphere. Great Red Spot One of the most famous features on Jupiter's surface is its Great Red Spot, a storm that’s been raging on the planet for over 400 years. It's so wide that about three Earths could fit within its boundaries. It's not the only storm, though -- two smaller ones nicknamed Oval BA and Little Red Spot have been churning alongside the Great Red Spot for many years. Infrared observations show complex swirls of warmer and cooler areas within the storms, and allow astronomers to track the heat flow and temperature patterns in their centers. Cosmic Collisions Jupiter has a rather violent history of getting hit by various celestial visitors. In 1994, a large comet called Shoemaker-Levy 9 crashed into the planet, leaving massive dark scars across the planet that lasted for several months.

Then, in July 2009, another collision by an object about the size of the Titanic crashed into the planet causing an ocean-size scar. Infrared telescopes picked up this collision as a bright spot that gradually stretched out into a bright line as the hot lower layers of the planet were thrown up into the upper atmosphere by the collision. The infrared data allowed astronomers to observe the atmospheric temperatures and chemical conditions resulting from the 2009 impact, and enabled them to get a "taste" of the chemicals in Jupiter's lower layers. Searing temperatures and the presence of blistering hot ammonia flooding up from deep within Jupiter's atmosphere revealed that the debris from the 2009 impact was heavier than the debris from comet Shoemaker-Levy 9, leading astronomers to conclude that the 2009 “impactor” was a rocky asteroid rather than an icy comet. We've learned a lot by studying impacts like these. As a matter of fact, we now think that Jupiter is vital to the very survival of life here on Earth. Thanks to its location and its enormous gravitational pull, the King of the Planets acts as a gatekeeper, sweeping up comets and asteroids that might otherwise crash into Earth!

Saturn The beauty of Saturn, the Lord of the Rings, has fascinated everyone who has ever seen it through even a small telescope. Like Jupiter, Saturn is a gas giant, which means it's mostly made of gases like hydrogen and helium, and it doesn’t have a solid surface in the way that rocky planets like Earth do. Saturn is mainly made of hydrogen and helium gas. Its density is so low that it would float in water. Also like Jupiter, Saturn gives off almost twice as much energy as it receives from the Sun, because it has its own internal heat source, powered by the slow gravitational collapse that started when the planet first formed. But even with this internal heat, Saturn is colder than Jupiter because it’s farther away from the Sun. With the extremely cold temperatures in the Saturnian system, ranging from about 55 K to 110 K (-220 C to -160 C, -360 F to -260 F), Saturn, its rings (which are made out of particles of ice and dust), and its moons give off most of their energy at infrared wavelengths.

Saturn's Atmosphere The night side of Saturn and its north polar region are dominated by infrared energy that wells up from deep within the planet's atmosphere. Varying amounts of upper atmospheric clouds block the infrared light, causing a banded and speckled appearance that constantly shifts due to Saturn's strong winds. Lit from below by Saturn's internal infrared glow, bright areas show where the cloud cover is thinnest, allowing the heat from the planet's interior to blaze through. The northern hemisphere is almost twice as bright as the southern hemisphere. Scientists think this is because there are fewer high-level fine particles in the northern hemisphere to block Saturn's glow. A new ring for Saturn In 2011, astronomers using Spitzer's infrared detectors made a startling discovery around Saturn: a new supersized ring that had lain previously undiscovered. The ring is made of diffuse ice and dust particles that are dark in color, and so invisible to regular telescopes. By looking in the infrared using Spitzer, astronomers were able to spot the heat signature of these particles, and map out the band of material. Moon Mystery Solved? The discovery of Saturn's new ring may have solved an age-old mystery of one of Saturn's moons, Iapetus.

Iapetus has a curious appearance - it's an icy moon, and so should reflect sunlight brightly from the whole surface, but its leading side is very dark, with a reflectivity similar to coal. This pattern of light and dark baffled astronomers for decades, but the existence of a new ring near Iapetus' orbit gave them a possible explanation. Astronomers now think that Iapetus slams into the material from the new ring as it travels in its orbit around Saturn, splattering the dark dust over the moon's surface like bugs on a windshield, covering the bright ice on one half of the moon with a dingy layer of grime. Published: 12 August, 2013 90% of the Earth's atmosphere is in a thin band, only 10 km high. That 10 km is all that protects us from deep space. Continue the conversation on The Solar System: Jupiter | The Institute for Creation Research The Solar System: Jupiter Resources › Physical Sciences Resources › Astronomy The planet Jupiter is a wonderful example of the creativity of the Lord. It is remarkably different from the worlds we have examined previously in this Impact series.

Jupiter does not possess a solid surface but is an enormous spheroid of gas—eleven times the diameter of Earth—held together by its own gravity. The gas pressure increases with depth, eventually becoming liquid. Properties of Jupiter The fifth planet away from the sun, Jupiter is composed primarily of hydrogen and helium, the same gases that comprise the sun. However, the much cooler temperature of Jupiter allows the formation of molecules such as ammonia, water, and methane from various trace elements. These molecular compounds create Jupiter’s colorful cloud formations. Jupiter is massive—the equivalent of 318 Earths! If we could put it on a scale, it would weigh more than twice as much as all the other planets combined. Jupiter is so massive that its gravity slightly, but noticeably, affects the motions of the other planets. Astronomers must factor this into their computations when predicting the precise positions of planets. Due to its large size, the disk of Jupiter is easily visible with virtually any small telescope, or even through good binoculars, despite being 500 million miles away from Earth.

A number of Jupiter’s properties are consistent with its biblical age of about 6,000 years but are difficult to explain via frameworks that adhere to a multi-billion-year-old solar system. One of these is its strong magnetic field. Since magnetic fields naturally decay with time, it is hard to understand how Jupiter could maintain such a powerful field over billions of years. Another indication of youth is Jupiter’s internal heat. Jupiter emits nearly twice the amount of energy that it receives from the sun. Like popcorn fresh out of the microwave, planets gradually cool as they radiate heat into space. Jupiter is large enough to do this for thousands of years. But if it were really billions of years old, why hasn’t it cooled off by now? Views of Jupiter Jupiter is an ideal target for a small backyard telescope. The planet is easy to find because it is extremely bright—only Venus is brighter. Jupiter shines through the most light-polluted city skies and always puts on a good show, revealing detailed cloud features to viewers. Powerful winds stretch the clouds into colorful “belts” and “zones” that encircle Jupiter parallel to its equator.

Belts are the dark brownish-orange features and zones are lighter in color.1 Like Earth’s jet streams, these clouds mark the differential rotation of Jupiter’s atmosphere. Typically, the Northern and Southern Equatorial Belts that sandwich Jupiter’s equator are the most visible. But with larger telescopes under good viewing conditions, it is often possible to see several thinner belts and perhaps even small disturbances taking place within them. Unsurprisingly, these cloud formations are dynamic, changing from year to year, growing or shrinking slightly, and experiencing subtle changes in color. Occasionally, a belt disappears completely for some time. This happened to the Southern Equatorial Belt in 2010, radically changing the appearance of Jupiter until the belt returned in 2011. Since it never looks exactly the same way twice, Jupiter is always fun to watch. The Great Red Spot, a large, somewhat permanent feature just below Jupiter’s Southern Equatorial Belt, is of particular interest. The Red Spot is a storm vortex, essentially a hurricane, roughly twice the width of Earth.2 Hurricanes on Earth are powered by warm ocean water and dissipate when they move over land. However, since Jupiter has no land, its Great Red Spot continues indefinitely.

At least 349 years old, this magnificent storm was first discovered by Robert Hooke in 1664. Before this time, telescopes were not optically sufficient to discern such features, so the Red Spot may actually be much older. Despite its name, the Great Red Spot is currently more of an orange hue and its color changes with time. In the 1990s it had turned a light pink color, reducing its contrast and making it very difficult to see through backyard telescopes. Though it has darkened since then, the spot is not always easy to see. Since Jupiter rotates, the Great Red Spot is on the other side of the planet and impossible to see 50 percent of the time. But even when on the Earth-facing side of Jupiter, the Great Red Spot is hard to see near the limb (the edge of the disk). The best view is when the spot is said to “transit” or pass near the horizontal center of the disk, an occurrence predictable up to a month or so in advance. Viewers can find upcoming transit times posted on various astronomy websites. Jupiter rotates in less than 10 hours—faster than any other planet.

This rapid rotation, combined with the extraordinary size of Jupiter, causes the planet to bulge at the equator. Even through a decent backyard telescope it is clear that Jupiter is not exactly round. Such rapid rotation also means that if you view Jupiter twice in one evening separated by a couple of hours, you will get a different view on the second pass since Jupiter will have undergone one fifth of its rotation. The effect is particularly noticeable when the Red Spot is near Jupiter’s center. The Galilean Satellites Jupiter itself is wonderful to view in a small telescope, but the observer will also be struck by the presence of four beautiful, bright “stars” that are always near Jupiter and aligned with its equator. These are moons—natural satellites that orbit Jupiter. They always appear in a nearly straight line because they orbit in the plane of Jupiter’s equator, and we see the Jupiter system from nearly edge-on; it is the same reason a Frisbee looks like a straight line when viewed from the side. These four moons are even bright enough to be seen in binoculars. They were the first moons discovered orbiting another planet, a discovery that changed our view of the universe.

Before Galileo constructed his own telescope in 1609 and began peering into the heavens, no one had considered the possibility that other planets could have moons. As far as anyone knew, there was simply the moon that orbits Earth. At that time, most astronomers believed that everything orbited Earth, including the other planets and the sun—this is known as a geocentric view. When Galileo first pointed his telescope at Jupiter, he was delighted to discover four new worlds never before known by anyone other than God. What a moment that must have been!3 And by observing these moons night after night, he could clearly see that they were orbiting Jupiter. This strongly refuted the geocentric claim that everything must orbit around Earth. Galileo had found a clear counterexample that paved the way for increased acceptance of the heliocentric solar system—the notion that planets, including Earth, orbit the sun.4 In honor of their discoverer, these four moons are now called the Galilean satellites. In order of increasing orbital distance from Jupiter, the Galilean satellites are named Io, Europa, Ganymede, and Callisto. Unlike gaseous Jupiter, these moons are solid bodies composed of rock and ice.

Jupiter and its moons are like a miniature solar system with the inner moons orbiting faster than the others. Io takes only 1.77 days to orbit Jupiter, and the orbital periods of Europa, Ganymede, and Callisto are 3.55 days, 7.15 days, and 16.7 days respectively. Notice the pattern: Europa’s period is twice that of Io, and Ganymede’s period is twice that of Europa. This is an example of orbital resonance.5 Callisto alone is not in resonance. Using a small telescope, it is possible to actually see these moons orbiting over time. If you made a careful mental note of the positions of the Galilean moons at a given moment and then looked again an hour later, you might notice that their locations appreciably changed. To see celestial objects change so drastically in such a short time is a rare delight. The Galilean moons are comparable in size to Earth’s moon. Io is 2,264 miles in diameter—only five percent larger than the moon. Europa is 10 percent smaller than our moon, and Callisto is 39 percent larger.

Ganymede is the largest moon in the solar system at 50 percent larger than Earth’s moon. Ganymede is even larger than the planet Mercury! So, if this moon orbited the sun directly instead of Jupiter, it would certainly be classified as a planet. Due to its larger surface area, Ganymede appears noticeably brighter than Io and Europa and slightly brighter than Callisto. Each of the Galilean satellites is an amazing world, but Io is the clear winner in terms of its unique qualities. High-resolution images of Io taken by the Voyager spacecrafts in 1979 revealed that, in contrast to all other known moons, this moon has absolutely no impact craters. Instead, it is covered with sulfuric compounds that are responsible for its colorful surface. Volcanoes pervade the surface of Io. Some are even taller than Mount Everest. Eruptions are almost constant, repeatedly covering the surface with volcanic material and erasing any previous record of impact craters. Io is the most volcanically active world in the solar system. When Voyager 1 flew past Io, it detected nine volcanoes erupting simultaneously!

The “gravitational stretching” occurring every 3.55 days, when Io passes between Jupiter and Europa, seems to provide the internal energy required for Io’s volcanism. More Moons and Rings Galileo’s telescope was quite small and limited—comparable to modern binoculars. In the centuries that followed, astronomers discovered many additional fainter, smaller moons with the aid of higher-quality telescopes and spacecraft. At latest count, Jupiter has 67 known moons—more than any other planet!6 Aside from the Galilean satellites, all these moons are very small, generally only a few miles across. Based on their orbital properties, these moons fall into eight natural groups. One group consists of the only four moons that are closer than the Galilean satellites to Jupiter. The orbits of these inner moons and the orbits of the Galilean moons are nearly circular, are in the same plane as Jupiter’s equator, and are prograde, meaning they orbit in the same direction that Jupiter rotates.7 The next seven beyond Callisto are also prograde, but their orbits tend to be tilted substantially, relative to Jupiter’s equator, and are more elliptical than those of the inner moons.

The remaining 52 moons also have tilted, elliptical orbits, but, amazingly, they are all retrograde—orbiting in the opposite direction of Jupiter’s rotation. So, the region where moons orbit in one direction is separate from the region where they orbit the other way. This reduces the possibility of collision or close gravitational perturbations.8 Jupiter also has a system of rings like Saturn that were first detected in 1979 by the Voyager 1 spacecraft. These rings are much less substantial than Saturn’s, however, and too faint to be seen with a backyard telescope. The main rings consist of dust particles orbiting mainly around and inside the orbit of Jupiter’s innermost moons, Metis and Adrastea. An even thinner “gossamer ring” extends farther out. Conclusions Most of what we now know about this fascinating planet was hidden from humanity for thousands of years. To our distant ancestors, Jupiter was a bright point of light in our night sky. Who would have imagined that this bright “star” would have so many remarkable characteristics? And what other celestial secrets has the Lord hidden for us to find and cherish? References Belts are regions where we are able to see deeper into Jupiter’s atmosphere.

Zones are lighter because they are clouds of ammonia that are higher in the atmosphere and block the brownish-orange color of the lower atmosphere. Hurricanes on Earth are low-pressure systems. The Red Spot in Jupiter’s southern hemisphere is a high-pressure system. For this reason, it rotates counterclockwise—in the opposite direction of hurricanes in Earth’s southern hemisphere (which rotate clockwise). Galileo published his discoveries in 1610 in a small, enjoyable book called The Starry Messenger. Galileo’s sense of wonder and excitement are obvious throughout. He knew that he was seeing something that no human being had ever seen—something that would forever change our perceptions of the solar system. Galileo challenged a number of the prevailing scientific views of the day. Curiously, the Roman Catholic Church had largely adopted the mainstream scientific view of the day (geocentrism) and incorporated it into their theology. They even attempted to use poetic passages in Scripture, such as Psalm 93:1 , as evidence for geocentrism. However, such passages were ripped out of context. The psalmist is not addressing motion in the sense of Newtonian physics but rather the inescapable stability of the universe caused by the power of God.

Many people think that the Galileo incident was an example of science prevailing over Scripture when in fact it was one view of science prevailing over another view that the Roman Catholic Church had endorsed. Perhaps the lesson to take away is that we should not tie the Bible to any specific scientific theory but instead let Scripture interpret Scripture. A resonance is when the ratio of two periods can be expressed as a simple fraction or integer, such as 1-to-1 or 3-to-4. In this case, the inner three Galilean moons have an orbital resonance of 4:2:1. That is, Io orbits four times for every two orbits of Europa and every one orbit of Ganymede. In this Impact series, we first explored the concept of resonance in the article on Mercury in the August 2013 issue of Acts & Facts. Planets: Jupiter. Solar System Exploration. NASA. Posted on solarsystem.nasa.gov, accessed October, 2, 2013. Jupiter rotates counterclockwise as viewed from above its North Pole. When one massive object passes closely by another, their mutual gravity will affect their orbits. In some cases, this can result in one of the objects being ejected from the system. * Dr.

Lisle is Director of Physical Sciences at the Institute for Creation Research and received his Ph.D. in astrophysics from the University of Colorado. Cite this article: Jason Lisle, Ph.D. 2013. The Solar System: Jupiter . Acts & Facts. 42 (12). Astronomy for Kids - Uranus Voyager 2 A Seemingly Featureless Planet Uranus, along with Neptune and Pluto, is in the most distant region of our solar system. The giant planet, which is another of the gas giants of our solar system, is more than twice as far away from the Sun as Saturn. If you get a chance to look at Uranus through a telescope, all you will see is a faint blue disk that appears exceptionally dull and lifeless. Even pictures sent back by the Voyager mission and the Hubble Space Telescope seem to show that Uranus is a dull, unexciting place. As always, though, things aren't what they seem. Uranus has many interesting features, including its ring system, varied moons and much more. The bland face that the planet shows to us humans hides high speed winds, the fact that Uranus is tilted on its side and a very mysterious weather system.

Read on to find out more about this mysterious world! Uranus from Voyager A picture of Uranus taken by the Voyager 2 spacecraft. A Pale Blue-Green Disc Although the Voyager spacecraft visited the seventh planet during its epic journey through our solar system, the pictures it sent back from Uranus were somewhat disappointing. We had hoped to see some color bands like there are on Jupiter or at least some faint colors, but the face the planet presents doesn't seem to vary, regardless of how close or far away from it you are. Uranus, unlike Jupiter or Saturn, does not seem to have a solid core of any kind. The planet does contain some rocky material, but the planet is almost all gas, with the outer layer of methane providing the blue color we see in the picture at the right. The pale blue image we see of Uranus hides the fact that the surface of the planet is swept by "winds" moving along at several hundred miles per hour. Scientists were able to detemine this by carefully studying the images that Voyager sent back. A Tilted World Click here to learn more about the tilt of Uranus.

A World on Tilt When Voyager arrived at Uranus, it discovered a number of moons that were unknown to us. In addition, we found out that the planet is tilted on its side! All the other planets in our solar system pretty much have their equator lined up directly with the Sun. Uranus's equator is tilted at almost right angles to the Sun, which gives the planet very unusual seasons and gives us a different view of the planet depending on when we look at it. This proves once again that things are hardly ever as they seem on the surface. Click on the link at right to find out more about the planet's tilt and what effects it has. The Moons of Uranus Click here to learn more about the moons of Uranus. A Wide Variety of Very Unusual Moons Before the Voyager mission arrived at Uranus, we knew that Uranus had five moons, but we didn't really know much about them because of the planet's great distance from the Sun. What a surprise we had waiting for us! Not only did Voyager show us that there were eleven more moons orbiting the giant planet, it also revealed that the moons were very interesting in their own right.

There was a moon with cliffs on it higher than Mount Everest here on Earth, one with one very smooth side and one very rough side and much, much more. Click on the link at right to find out more about the some of the fascinating moons of Uranus. Solve the Puzzle! Test your knowledge of Uranus by solving the word search puzzle we have. Click on the icon at left to try and solve the puzzle. The puzzle will open in a small popup window so you can refer back to this page for the answers. Find Out More About Uranus The Solar System Home | Site Map | What's New | Image Index | Copyright | Posters | ScienceViews | Science Fiction Timelines | The Solar System For I dipped into the Future, far as human eye could see; saw the vision of the world, and all the wonder that would be. -Alfred Lord Tennyson, 1842 Table of Contents Multiwavelength Milky Way Our solar system consists of an average star we call the Sun , the planets Mercury , Venus , Earth , Mars , Jupiter , Saturn , Uranus , Neptune , and Pluto . It includes: the satellites of the planets; numerous comets , asteroids , and meteoroids; and the interplanetary medium.

The Sun is the richest source of electromagnetic energy (mostly in the form of heat and light) in the solar system. The Sun's nearest known stellar neighbor is a red dwarf star called Proxima Centauri, at a distance of 4.3 light years away. The whole solar system, together with the local stars visible on a clear night, orbits the center of our home galaxy, a spiral disk of 200 billion stars we call the Milky Way . The Milky Way has two small galaxies orbiting it nearby, which are visible from the southern hemisphere. They are called the Large Magellanic Cloud and the Small Magellanic Cloud. The nearest large galaxy is the Andromeda Galaxy . It is a spiral galaxy like the Milky Way but is 4 times as massive and is 2 million light years away. Our galaxy, one of billions of galaxies known, is traveling through intergalactic space. The planets, most of the satellites of the planets and the asteroids revolve around the Sun in the same direction, in nearly circular orbits. When looking down from above the Sun's north pole, the planets orbit in a counter-clockwise direction. The planets orbit the Sun in or near the same plane, called the ecliptic .

Pluto is a special case in that its orbit is the most highly inclined (18 degrees) and the most highly elliptical of all the planets. Because of this, for part of its orbit, Pluto is closer to the Sun than is Neptune . The axis of rotation for most of the planets is nearly perpendicular to the ecliptic. The exceptions are Uranus and Pluto , which are tipped on their sides. Composition Of The Solar System The Sun contains 99.85% of all the matter in the Solar System. The planets, which condensed out of the same disk of material that formed the Sun, contain only 0.135% of the mass of the solar system. Jupiter contains more than twice the matter of all the other planets combined. Satellites of the planets, comets, asteroids, meteoroids, and the interplanetary medium constitute the remaining 0.015%. The following table is a list of the mass distribution within our Solar System. Sun: 99.85% Interplanetary Space Nearly all the solar system by volume appears to be an empty void. Far from being nothingness, this vacuum of "space" comprises the interplanetary medium.

It includes various forms of energy and at least two material components: interplanetary dust and interplanetary gas. Interplanetary dust consists of microscopic solid particles. Interplanetary gas is a tenuous flow of gas and charged particles, mostly protons and electrons -- plasma -- which stream from the Sun , called the solar wind . The solar wind can be measured by spacecraft, and it has a large effect on comet tails. It also has a measurable effect on the motion of spacecraft. The speed of the solar wind is about 400 kilometers (250 miles) per second in the vicinity of Earth's orbit. The point at which the solar wind meets the interstellar medium, which is the "solar" wind from other stars, is called the heliopause. It is a boundary theorized to be roughly circular or teardrop-shaped, marking the edge of the Sun's influence perhaps 100 AU from the Sun. The space within the boundary of the heliopause, containing the Sun and solar system, is referred to as the heliosphere. The solar magnetic field extends outward into interplanetary space; it can be measured on Earth and by spacecraft.

The solar magnetic field is the dominating magnetic field throughout the interplanetary regions of the solar system, except in the immediate environment of planets which have their own magnetic fields. The Terrestrial Planets The terrestrial planets are the four innermost planets in the solar system, Mercury , Venus , Earth and Mars . They are called terrestrial because they have a compact, rocky surface like the Earth's. The planets, Venus, Earth, and Mars have significant atmospheres while Mercury has almost none. The following diagram shows the approximate distance of the terrestrial planets to the Sun. The Jovian Planets Jupiter , Saturn , Uranus , and Neptune are known as the Jovian (Jupiter-like) planets, because they are all gigantic compared with Earth, and they have a gaseous nature like Jupiter's. The Jovian planets are also referred to as the gas giants, although some or all of them might have small solid cores. The following diagram shows the approximate distance of the Jovian planets to the Sun. Our Milkyway Galaxy This image of our galaxy, the Milky Way, was taken with NASA's Cosmic Background Explorer's (COBE) Diffuse Infrared Background Experiment (DIRBE).

This never-before-seen view shows the Milky Way from an edge-on perspective with the galactic north pole at the top, the south pole at the bottom and the galactic center at the center. The picture combines images obtained at several near-infrared wavelengths. Stars within our galaxy are the dominant source of light at these wavelengths. Even though our solar system is part of the Milky Way, the view looks distant because most of the light comes from the population of stars that are closer to the galactic center than our own Sun. (Courtesy NASA) Our Milky Way Gets a Makeover Like early explorers mapping the continents of our globe, astronomers are busy charting the spiral structure of our galaxy, the Milky Way. Using infrared images from NASA's Spitzer Space Telescope, scientists have discovered that the Milky Way's elegant spiral structure is dominated by just two arms wrapping off the ends of a central bar of stars. Previously, our galaxy was thought to possess four major arms. This artist's concept illustrates the new view of the Milky Way, along with other findings presented at the 212th American Astronomical Society meeting in St. Louis, Mo.

The galaxy's two major arms (Scutum-Centaurus and Perseus) can be seen attached to the ends of a thick central bar, while the two now-demoted minor arms (Norma and Sagittarius) are less distinct and located between the major arms. The major arms consist of the highest densities of both young and old stars; the minor arms are primarily filled with gas and pockets of star-forming activity. The artist's concept also includes a new spiral arm, called the "Far-3 kiloparsec arm," discovered via a radio-telescope survey of gas in the Milky Way. This arm is shorter than the two major arms and lies along the bar of the galaxy. Our sun lies near a small, partial arm called the Orion Arm, or Orion Spur, located between the Sagittarius and Perseus arms. (Courtesy NASA/JPL-Caltech) Spiral Galaxy, NGC 4414 The majestic galaxy, NGC 4414, is located 60 million light-years away. Like the Milky Way, NGC 4414 is a giant spiral-shaped disk of stars, with a bulbous central hub of older yellow and red stars.

The outer spiral arms are considerably bluer due to ongoing formation of young, blue stars, the brightest of which can be seen individually at the high resolution provided by the Hubble camera. The arms are also very rich in clouds of interstellar dust, seen as dark patches and streaks silhouetted against the starlight. (Courtesy NASA/STSCI) Obliquity of the Eight Planets This illustration shows the obliquity of the eight planets. Obliquity is the angle between a planet's equatorial plane and its orbital plane. By International Astronomical Union (IAU) convention, a planet's north pole lies above the ecliptic plane. By this convention, Venus, Uranus, and Pluto have a retrograde rotation, or a rotation that is in the opposite direction from the other planets. (Copyright 2008 by Calvin J. Hamilton) The Solar System During the past three decades a myriad of space explorers have escaped the confines of planet Earth and have set out to discover our planetary neighbors. This picture shows the Sun and all nine planets of the solar system as seen by the space explorers.

Starting at the top-left corner is the Sun followed by the planets Mercury , Venus , Earth , Mars , Jupiter , Saturn , Uranus , Neptune , and Pluto . (Copyright 1998 by Calvin J. Hamilton) The Largest Moons and Smallest Planets This image shows the relative sizes of the largest moons and the smallest planets in the solarsystem. The largest satellites pictured in this image are: Ganymede (5262 km), Titan (5150 km), Callisto (4806 km), Io (3642 km), the Moon (3476 km), Europa (3138 km), Triton (2706 km), and Titania (1580 km). Both Ganymede and Titan are larger than planet Mercury followed by Io, the Moon, Europa, and Triton which are larger than the planet Pluto . (Copyright Calvin J. Hamilton) Diagram of Portrait Frames On February 14, 1990, the cameras of Voyager 1 pointed back toward the Sun and took a series of pictures of the Sun and the planets, making the first ever "portrait" of our solar system as seen from the outside.

This image is a diagram of how the frames for the solar system portrait were taken. (Courtesy NASA/JPL) All Frames from the Family Portrait This image shows the series of pictures of the Sun and the planets taken on February 14, 1990, for the solar system family portrait as seen from the outside. In the course of taking this mosaic consisting of a total of 60 frames, Voyager 1 made several images of the inner solar system from a distance of approximately 6.4 billion kilometers (4 billion miles) and about 32° above the ecliptic plane. Thirty-nine wide angle frames link together six of the planets of our solar system in this mosaic. Outermost Neptune is 30 times further from the Sun than Earth . Our Sun is seen as the bright object in the center of the circle of frames. The insets show the planets magnified many times. (Courtesy NASA/JPL) Portrait of the Solar System These six narrow-angle color images were made from the first ever "portrait" of the solar system taken by Voyager 1 , which was more than 6.4 billion kilometers (4 billion miles) from Earth and about 32° above the ecliptic .

Mercury is too close to the Sun to be seen. Mars was not detectable by the Voyager cameras due to scattered sunlight in the optics, and Pluto was not included in the mosaic because of its small size and distance from the Sun. These blown-up images, left to right and top to bottom are Venus , Earth , Jupiter , Saturn , Uranus , and Neptune . (Courtesy NASA/JPL) The following table lists statistical information for the Sun and planets: Distance

Question: Which planet in our solar system is almost twice as far away from the Sun as Jupiter?
Answer: Saturn