Fans of astronomy are no doubt familiar with the work of Kevin Gill. In the past, he has brought us visualizations of what the Earth would look like if it had a system of rings, what a “Living Mars” would look like – i.e. if it was covered in oceans and lush vegetation – and am artistic rendition of the places we’ve been in our Solar System.
In his latest work, which once again merges the artistic and astronomical, Gill has created a series of images that show Saturn’s moon of Daphnis, and the effect it has on Saturn’s Keeler Gap. Through these images – titled “Daphnis in the Keeler Gap” and “Daphnis and Waves Along the Keeler Gap” – we get to see an artistic rendition of how one of Saturn’s moons interacts with its beautiful ring system.
As one of Saturn’s smallest moons – measuring just 8 km (~5 mi) in diameter – the existence of Daphnis had been previously inferred by astronomers based on the gravitational ripples that were observed on the outer edge of the Keeler Gap. This 42 km (26 mi) wide gap, which lies in Saturn’s A Ring and is approximately 250 km from the its outer edge, is kept clear by Daphnis’ orbit around the planet.
In 2005, the Cassini space probe finally confirmed the existence of this tiny moon. After analyzing images provided by the probe, the Cassini Imaging Science Team concluded that Daphnis’ path and orbit induce a wavy pattern in the edge of the gap. These waves reach a distance of 1.5 km (0.93 mi) above the ring, due to Daphnis being slightly inclined to the ring’s plane.
However, all the images taken by Cassini showed this effect from a great distance. In order to help people appreciate what it must look like close-up, Gill decided to create the visuals you see here. From his images, the passage of Daphnis is shown to give the A Ring a rippled, wavy appearance. In addition, one can see how Daphnis is inclined slightly above the plane of the A Ring, causing the waves to reach upward.
As Kevin Gill told Universe Today via email, these images were the largely inspired by the most recent images of Saturn’s rings that were provided by Cassini space probe, which returned to an equatorial orbit a few months ago after spending two years in high-inclination orbits:
“These are inspired by a general interest in the moon-ring interactions and some recent Cassini views of Daphnis on the 15th (shown below). This is one of the many aspects of the Saturn system that I imagine would be absolutely breathtaking if you could see it in person and ended up being rather simple to model in Maya.”
Jason Major, a graphic designer who owns the well-known astronomy website Lights in the Dark, eloquently explained what the rings look like back in 2011. Roughly a year after NASA released other Cassini images that showed Daphnis and its influence on the Keeler Gap, he wrote:
“As [Daphnis] travels, its gravity “sculpts” the fine, icy particles along the edge of the gap into scallops, not only horizontally but also vertically, sending waves of ring bits as high as a mile or so above and below the ringplane. This phenomenon became clear as Saturn approached its spring equinox last August, when light from the sun hit the planet parallel to the equator and made small details like this visible because of the shadows they cast. Even now, almost a year later, the angle of the sunlight is still low enough to keep the shadows long…”
Such visualizations are a testament to missions like Cassini, and other long-range space probes that are bettering our understanding of the outer Solar System. They also demonstrate the importance of public interest and involvement in our ongoing efforts to explore and study the Universe as we know it.
To have a gander at other examples of Gill’s work, click on the link below.
The post New JPL Visualization Of Waves In Saturn’s Rings Puts You In The Keeler Gap appeared first on Universe Today.
Continuing with our “Definitive Guide to Terraforming“, Universe Today is happy to present our guide to terraforming Saturn’s Moons. Beyond the inner Solar System and the Jovian Moons, Saturn has numerous satellites that could be transformed. But should they be?
Around the distant gas giant Saturn lies a system of rings and moons that is unrivaled in terms of beauty. Within this system, there is also enough resources that if humanity were to harness them – i.e. if the issues of transport and infrastructure could be addressed – we would be living in an age a post-scarcity. But on top of that, many of these moons might even be suited to terraforming, where they would be transformed to accommodate human settlers.
As with the case for terraforming Jupiter’s moons, or the terrestrial planets of Mars and Venus, doing so presents many advantages and challenges. At the same time, it presents many moral and ethical dilemmas. And between all of that, terraforming Saturn’s moons would require a massive commitment in time, energy and resources, not to mention reliance on some advanced technologies (some of which haven’t been invented yet).
The Cronian Moons:
All told, Saturn system is second only to Jupiter in terms of its number of satellites, with 62 confirmed moons. Of these, the largest moons are divided into two groups: the inner large moons (those that orbit close to Saturn within its tenuous E-Ring) and the outer large moons (those beyond the E-Ring). They are, in order of distance from Saturn, Mimas, Enceladus, Tethys, Dione, Rhea, Titan, and Iapetus.
These moons are all composed primarily of water ice and rock, and are believed to be differentiated between a rocky core and an icy mantle and crust. Among them, Titan is appropriately named, being the largest and most massive of all the inner or outer moons (to the point that it is larger and more massive than all the others combined).
In terms of their suitability for human habitation, each one present its own share of pros and cons. These include their respective sizes and compositions, the presence (or absence) of an atmosphere, gravity, and the availability of water (in ice form and subsurface oceans), And in the end, it is the presence of these moons around Saturn that makes the system an attractive option for exploration and colonization.
As aerospace engineer and author Robert Zubrin stated in his book Entering Space: Creating a Spacefaring Civilization, Saturn, Uranus and Neptune could one day become “the Persian Gulf of the Solar System”, due to their abundance of hydrogen and other resources. Of these systems, Saturn would be the most important, thanks to its relative proximity to Earth, low radiation, and excellent system of moons.
Terraforming one or more of Jupiter’s moons would be a relatively straightforward process. In all cases, this would involve heating the surfaces through various means – like thermonuclear devices, impacting the surface with asteroids or comets, or focusing sunlight with orbital mirrors – to the point that surface ice would sublimate, releasing water vapor and volatiles (such as ammonia and methane) to form an atmosphere.
However, due to the comparatively low amounts of radiation coming from Saturn (compared to Jupiter), these atmospheres would have to be converted to a nitrogen-oxygen rich environment through means other than radiolysis. This could be done by using the same orbital mirrors to focus sunlight onto the surfaces, triggering the creation of oxygen and hydrogen gas from water ice through photolysis. While the oxygen would remain closer to the surface, the hydrogen would escape into space.
The presence of ammonia in many of the moon’s ices would also mean that a ready supply of nitrogen could be created to act as a buffer gas. By introducing specific strains of bacteria into the newly created atmospheres – such as the Nitrosomonas, Pseudomonas and Clostridium species – the sublimated ammonia could be converted into nitrites (NO²-) and then nitrogen gas.
Another option would be to employ a process known as “paraterraforming” – where a world is enclosed (in whole or in part) in an artificial shell in order to transform its environment. In the case of the Cronian moons, this would involve building large “Shell Worlds” to encase them, keeping the newly-created atmospheres inside long enough to effect long-term changes.
Within this shell, a Cronian moon could have its temperatures slowly raised, the water-vapor atmospheres could be exposed to ultra-violet radiation from internal UV lights, bacteria could then be introduced, and other elements added as needed. Such a shell would ensure that the process of creating of an atmosphere could be carefully controlled and none would be lost before the process was complete.
With a diameter of 396 km and a mass of 0.4×1020 kg, Mimas is the smallest and least massive of these moons. It is ovoid in shape and orbits Saturn at a distance of 185,539 km with an orbital period of 0.9 days. The low density of Mimas, which is estimated to be 1.15 g/cm³ (just slightly higher than that of water), indicates that it is composed mostly of water ice with only a small amount of rock.
As a result of this, Mimas is not a good candidate for terraforming. Any atmosphere that could be created by melting its ice would likely be lost to space. In addition, its low density would mean that the vast majority of the planet would be ocean, with only a small core of rock. This, in turn, makes any plans to settle on the surface impractical.
Enceladus, meanwhile, has a diameter of 504 km, a mass of 1.1×1020 km and is spherical in shape. It orbits Saturn at a distance of 237,948 km and takes 1.4 days to complete a single orbit. Though it is one of the smaller spherical moons, it is the only Cronian moon that is geologically active – and one of the smallest known bodies in the Solar System where this is the case. This results in features like the famous “tiger stripes” – a series of continuous, ridged, slightly curved and roughly parallel faults within the moon’s southern polar latitudes.
Large geysers have also been observed in the southern polar region that periodically release plumes of water ice, gas and dust which replenish Saturn’s E-ring. These jets are one of several indications that Enceladus has liquid water beneath it’s icy crust, where geothermal processes release enough heat to maintain a warm water ocean closer to its core.
The presence of a warm-water liquid ocean makes Enceladus an appealing candidate for terraforming. The composition of the plumes also indicate that the subsurface ocean is salty, and contains organic molecules and volatiles. These include ammonia and simple hydrocarbons like methane, propane, acetylene, and formaldehyde.
Ergo, once the icy surface was sublimated, these compounds would be released, triggering a natural greenhouse effect. Combined with photolysis, radiolysis, and bacteria, the water vapor and ammonia could also be converted to a nitrogen-oxygen atmosphere. The higher density of Enceladus (~1.61 g/cm3) indicates that it has a larger than average silicate and iron core (for a Cronian moon). This could provide materials for any operations on the surface, and also means that if the surface ice were to be sublimated, Enceladus would not consist mainly of incredibly deep oceans.
However, the presence of this liquid salt-water ocean, organic molecules and volatiles also indicates that the interior of Enceladus experiences hydrothermal activity. This energy source, combined with organic molecules, nutrients, and the prebiotic conditions for life, means that is possible that Enceladus is home to extraterrestrial life.
Much like Europa and Ganymede, these would probably take the form of extremophiles living in environments similar to Earth’s deep-ocean hydrothermal vents. As a result, terraforming Enceladus could result in the destruction of the natural life cycle on the moon, or release life forms that could prove harmful to any future colonists.
At 1066 km in diameter, Tethys is the second-largest of Saturn’s inner moons and the 16th-largest moon in the Solar System. The majority of its surface is made up of heavily cratered and hilly terrain and a smaller and smoother plains region. Its most prominent features are the large impact crater of Odysseus, which measures 400 km in diameter, and a vast canyon system named Ithaca Chasma – which is concentric with Odysseus and measures 100 km wide, 3 to 5 km deep and 2,000 km long.
With a mean density of 0.984 ± 0.003 grams per cubic centimeter, Tethys is believed to be comprised almost entirely of water ice. It is not currently known whether Tethys is differentiated into a rocky core and ice mantle. However, given the fact that rock accounts for less 6% of its mass, a differentiated Tethys would have a core that did not exceed 145 km in radius. On the other hand, Tethys’ shape – which resembles that of a triaxial ellipsoid – is consistent with it having a homogeneous interior (i.e. a mix of ice and rock).
Because of this, Tethys is also off the terraforming list. If in fact it has a tiny rocky interior, treating the surface to heating would mean that the vast majority of the moon would melt and be lost to space. Alternately, if the interior is a homogeneous mix of rock and ice, then all that would remain after melting occurred would be a cloud of debris.
With a diameter and mass of 1,123 km and 11×1020 kg, Dione is the fourth largest moon of Saturn. The majority of Dione’s surface is heavily cratered old terrain, with craters that measure up to 250 km in diameter. With an orbital distance of 377,396 km from Saturn, the moon takes 2.7 days to complete a single rotation.
Dione’s mean density of about 1.478 g/cm³ indicates that it is composed mainly of water ice, with a small remainder likely consisting of a silicate rock core. Dione also has a very thin atmosphere of oxygen ions (O+²), which was first detected by the Cassini space probe in 2010. While the source of this atmosphere is currently unknown, it is believed that it is the product of radiolysis, where charged particles from Saturn’s radiation belt interact with water ice on the surface to create hydrogen and oxygen (similar to what happens on Europa).
Because of this tenuous atmosphere, it is already known that sublimating Dione’s ice could produce an oxygen atmosphere. However, it is not currently known if Dione possesses the right combination of volatilizes to ensure that nitrogen gas can be created, or that a greenhouse effect will be triggered. Combined with Dione’s low density, this makes it an unattractive target for terraforming.
Measuring 1,527 km in diameter and 23×1020 kg in mass, Rhea is the second largest of Saturn’s moons and the ninth largest moon of the Solar System. With an orbital radius of 527,108 km, it is the fifth-most distant of the larger moons, and takes 4.5 days to complete an orbit. Like other Cronian satellites, Rhea has a rather heavily cratered surface, and a few large fractures on its trailing hemisphere.
With a mean density of about 1.236 g/cm³, Rhea is estimated to be composed of 75% water ice (with a density of roughly 0.93 g/cm³) and 25% of silicate rock (with a density of around 3.25 g/cm³). This low density means that although Rhea is the ninth-largest moon in the Solar System, it is also the tenth-most massive.
In terms of its interior, Rhea was originally suspected of being differentiated between a rocky core and an icy mantle. However, more recent measurements would seem to indicate that Rhea is either only partly differentiated, or has a homogeneous interior – likely consisting of both silicate rock and ice together (similar to Jupiter’s moon Callisto).
Models of Rhea’s interior also suggest that it may have an internal liquid-water ocean, similar to Enceladus and Titan. This liquid-water ocean, should it exist, would likely be located at the core-mantle boundary, and would be sustained by the heating caused from the decay of radioactive elements in its core. Interior ocean or not, the fact that the vast majority of the moon is composed of ice water makes it an unattractive option for terraforming.
As already noted, Titan is the largest of the Cronian moons. In fact, at 5,150 km in diameter, and 1,350×1020 kg in mass, Titan is Saturn’s largest moon and comprises more than 96% of the mass in orbit around the planet. Based on its bulk density of 1.88 g/cm3, Titan’s composition is half water ice and half rocky material – most likely differentiated into several layers with a 3,400 km rocky center surrounded by several layers of icy material.
It is also the only large moon to have its own atmosphere, which is cold, dense, and is the only nitrogen-rich dense atmosphere in the Solar System aside from Earth’s (with small amounts of methane). Scientists have also noted the presence of polycyclic aromatic hydrocarbons in the upper atmosphere, as well as methane ice crystals. Another thing Titan has in common with Earth, unlike every other moon and planet in the Solar System, is atmospheric pressure. On the surface of Titan, the air pressure is estimated to be around 1.469 bars (1.45 times that of Earth).
The surface of Titan, which is difficult to observe due to persistent atmospheric haze, shows only a few impact craters, evidence of cryovolcanoes, and longitudinal dune fields that were apparently shaped by tidal winds. Titan is also the only body in the Solar System beside Earth with bodies of liquid on its surface, in the form of methane–ethane lakes in Titan’s north and south polar regions.
With an orbital distance of 1,221,870 km, it is the second-farthest large moon from Saturn, and completes a single orbit every 16 days. Like Europa and Ganymede, it is believed that Titan has a subsurface ocean made of water mixed with ammonia, which can erupt to the surface of the moon and lead to cryovolcanism. The presence of this ocean, plus the prebiotic environment on Titan, has led some to suggest that life may exist there as well.
Such life could take the form of microbes and extremophiles in the interior ocean (similar to what is thought to exist on Enceladus and Europa), or could take the even more extreme form of methanogenic life forms. As has been suggested, life could exist in Titan’s lakes of liquid methane just as organisms on Earth live in water. Such organisms would inhale dihydrogen (H²) in place of oxygen gas (O²), metabolize it with acetylene instead of glucose, and then exhale methane instead of carbon dioxide.
However, NASA has gone on record as stating that these theories remain entirely hypothetical. So while the prebiotic conditions that are associated with organic chemistry exist on Titan, life itself may not. However, the existence of these conditions remains a subject of fascination among scientists. And since its atmosphere is thought to be analogous to Earth’s in the distant past, proponents of terraforming emphasize that Titan’s atmosphere could be converted in much the same way.
Beyond that, there are several reasons why Titan is a good candidate. For starters, it possess an abundance of all the elements necessary to support life (atmospheric nitrogen and methane), liquid methane, and liquid water and ammonia. Additionally, Titan has an atmospheric pressure one and a half times that of Earth, which means that the interior air pressure of landing craft and habitats could be set equal or close to the exterior pressure.
This would significantly reduce the difficulty and complexity of structural engineering for landing craft and habitats compared with low or zero pressure environments such as on the Moon, Mars, or the Asteroid Belt. The thick atmosphere also makes radiation a non-issue, unlike with other planets or Jupiter’s moons.
And while Titan’s atmosphere does contain flammable compounds, these only present a danger if they are mixed with sufficient enough oxygen – otherwise, combustion cannot be achieved or sustained. Finally, the very high ratio of atmospheric density to surface gravity also greatly reduces the wingspan needed for aircraft to maintain lift.
With all these things going for it, turning Titan into a livable world would be feasible given the right conditions. For starters, orbital mirrors could be used to direct more sunlight onto the surface. Combined with the moon’s already dense and greenhouse gas-rich atmosphere, this would lead to a considerable greenhouse effect that would melt the ice and release water vapor into the air.
Once again, this could be converted into a nitrogen/oxygen-rich mix, and more easily than with other Cronian moons since the atmosphere is already very rich in nitrogen. The presence of nitrogen, methane and ammonia could also be used to produce chemical fertilizers to grow food. However, the orbital mirrors would need to remain in place in order to ensure the environment did not become extremely cold again and revert to an icy state.
At 1,470 km in diameter and 18×1020 kg in mass, Iapetus is the third-largest of Saturn’s large moons. And at a distance of 3,560,820 km from Saturn, it is the most distant of the large moons, and takes 79 days to complete a single orbit. Due to its unusual color and composition – its leading hemisphere is dark and black whereas its trailing hemisphere is much brighter – it is often called the “yin and yang” of Saturn’s moons.
With an average distance (semi major axis) of 3,560,820 km, Iapetus takes 79.32 days to complete an single orbit of Saturn. Despite being Saturn’s third-largest moon, Iapetus orbits much farther from Saturn than its next closest major satellite (Titan). Like many of Saturn’s moons – particularly Tethys, Mimas and Rhea – Iapetus has a low density (1.088 ± 0.013 g/cm³) which indicates that it is composed primary of water ice and only about 20% rock.
But unlike most of Saturn’s larger moons, its overall shape is neither spherical or ellipsoid, instead consisting of flattened poles and a bulging waistline. Its large and unusually high equatorial ridge also contributes to its disproportionate shape. Because of this, Iapetus is the largest known moon to not have achieved hydrostatic equilibrium. Though rounded in appearance, its bulging appearance disqualifies it from being classified as spherical.
Because of this, Iapetus is not a likely contender for terraforming. If in fact its surface were melted, it too would be an ocean world with unrealistically deep seas, and this water would likely be lost to space.
To break it down, only Enceladus and Titan appear to be viable candidates for terraforming. However, in both cases, the process of turning them into habitable worlds where human beings could exist without the need for pressurized structures or protective suits would be a long and costly one. And much like terraforming the Jovian moons, the challenges can be broken down categorically:
- Resources and Infrastructure
- Ethical Considerations
In short, while Saturn may be abundant in resources and closer to Earth than either Uranus or Neptune, its really very far. On average, Saturn is approximately 1,429,240,400,000 kms away from Earth (or ~8.5 AU the equivalent of eight and a half times the average distance between the Earth and the Sun). To put that in perspective, it took the Voyager 1 probe roughly thirty-eight months to reach the Saturn system from Earth. For crewed spacecraft, carrying colonists and all the equipment needed to terraform the surface, it would take considerably longer to get there.
These ships, in order to avoid being overly large and expensive, would need to rely on cryogenics or hibernation-related technology in order to be smaller, faster and more cost-effective. While this sort of technology is being investigated for crewed missions to Mars, it is still very much in the research and development phase. What’s more, a large fleet of robotic spaceships and support craft would also be needed to build the orbital mirrors, capture asteroids or debris to use as impactors, and provide logistical support to crewed spaceships.
Unlike the crewed vessels, which could keep crews in stasis until their arrival, these ships would need to have advanced propulsion systems to ensure that they were able to make the trips to and from the Cronian moons in a realistic amount of time. All of this, in turn, raises the crucial issue of infrastructure. Basically, any fleet operating between Earth and Saturn would require a network of bases between here and there to keep them supplied and fueled.
So really, any plans to terraform Saturn’s moons would have to wait upon the creation of permanent bases on the Moon, Mars, the Asteroid Belt, and the Jovian moons. In addition, building orbital mirrors would require considerable amounts of minerals and other resources, many of which could be harvested from the Asteroid Belt or from Jupiter’s Trojans.
This process would be punitively expensive by current standards and (again) would require a fleet of ships with advanced drive systems. And paraterraforming using Shell Worlds would be no different, requiring multiple trips to and from the Asteroid Belt, hundreds (if not thousands) of construction and support craft, and all the necessary bases in between.
And while radiation is not a major threat in the Cronian system (unlike around Jupiter), the moons have been subject to a great deal of impacts over the course of their history. As a result, any settlements built on the surface would likely need additional protection in orbit, like a string of defensive satellites that could redirect comets and asteroids before they reached orbit.
Fourth, terraforming Saturn’s moons presents the same challenges as Jupiter’s. Namely, every moon that was terraformed would be an ocean planet And whereas most of Saturn’s moons are untenable due to their high concentrations of water ice, Titan and Enceladus are not that much better off. In fact, if all of Titan’s ice were melted, including the layer that is believed to sit beneath its interior ocean, its sea level would be up to 1700 km in depth!
Not only that, but this sea would surround a hydrous core, which would likely make the planet unstable. Enceladus would not fair any better, as gravity measurements by Cassini have shown that the density of the core is low, indicating that the core contains water in addition to silicates. So in addition to a deep ocean on its surface, its core might also be unstable.
And last, there are the ethical considerations. If both Enceladus and Titan are home to extra-terrestrial life, than any efforts to alter their environments could result in their destruction. Barring that, melting the surface ice could cause any indigenous life forms to proliferate and mutate, and exposure to them could prove to be a health hazard for human settlers.
Once again, when faced with all of these considerations, one is forced to ask, “why bother?” Why bother altering the natural environment of the Cronian moons when we could settle on them as is, and use their natural resources to usher in an age of post-scarcity? Quite literally, there is enough water ice, volatiles, hydrocarbons, organic molecules, and minerals in the Saturn system to keep humanity supplied indefinitely.
What’s more, without the effects of terraforming, settlements on Titan and Enceladus would probably be a lot more tenable. We could also fathom building settlements on the moons of Tethys, Dione, Rhea, and Iapetus as well, which would prove much more beneficial in terms of being able to harness the system’s resources.
And, as with Jupiter’s moons of Europa, Ganymede, and Callisto, foregoing the act of terraforming would mean there would be an abundant supply of resources that could be used to terraform other places – namely, Venus and Mars. As has been argued many times over, the abundance of methane, ammonia, and water ices in the Cronian system would be very useful in helping to turn “Earths twins” into “Earth-like” planets.
Once again, it would seem that the answer to the question “can/should we?” is a disappointing no.
We have written many interesting articles about terraforming here at Universe Today. Here’s The Definitive Guide To Terraforming, How Do We Terraform Mars?, How Do We Terraform Venus?, How Do We Terraform the Moon?, and How Do We Terraforming Jupiter’s Moons?
Astronomy Cast also has good episodes on the subject, like Episode 61: Saturn’s Moons.
And if you like the video, come check out our Patreon page and find out how you can get these videos early while helping us bring you more great content!
Titan is a moon shrouded in mystery. Despite multiple flybys and surface exploration conducted in the past few decades, this Cronian moon still manages to surprise us from time to time. In addition to having a dense atmosphere rich in hydrocarbons, which scientists believe may be similar to what Earth’s own atmosphere was like billions of years ago, it appears that methane is to Titan what water is to planet Earth.
In addition, methane fog was also observed by the Cassini space probe back in 2009 as it conducted a flyby of Titan. But recent findings by a team of researchers from York University indicates that the Huygens lander also detected fog during its short time on the surface. This evidence, combined with the data obtained by Cassini, have helped to shed light on the weather patterns of this mysterious moon.
In a paper that appeared in arXiv on March 14th, Dr. Christina Smith – a postdoctoral student from York University’s Center for Research in Earth and Space Sciences (CRESS) – described how the Huygens probe’s Side Looking Imager (SLI) obtained information that has since been analyzed to identify potential atmospheric features. These features show that Titan experiences meteorological phenomena which were not previously known.
In total, the team looked over 82 SLI images, which were all taken after the lander reached the surface. These were then calibrated, processed and examined for signs of atmospheric features. Of these, six showed evidence of an extended horizontal feature that differed in radiance from what was predicted at higher and lower regions. No other discernible features were detected.
The team concluded that this feature most likely originated from the presence of a fog bank close to the horizon that rose and fell during the period of observation. This indicated that it had recently rained in the area, which was a rather surprising find. Much like the observations made in 2009, the presence of methane fog shows that Titan has an active methane hydrological cycle.
In essence, this means that methane on Titan is subject to the same transfer process as water is here on Earth. Basically, liquid methane on the surface evaporates and is exchanged with the atmosphere, where it condenses to form fog banks and rain clouds. As Christina Smith told Universe Today via email:
“We initially set out to see if we could see features such as clouds from the Huygens SLI data, but the features we found don’t seem to be consistent with clouds and more likely are caused by a fog bank rising and falling over the time of observation. Fog had been seen before from orbit but never from the surface of Titan – this is what makes this work so exciting. This work is also a great example of how new insights and new findings can be made from “older” data sets.”
Looking over this old data for the sake of making new discoveries was made possible, in part, because of the ongoing investigations conducted by Martian rovers and their respective science teams. Brittany Cooper – an undergraduate research assistant at York University’s Center for Research in Mass Spectrometry, and the second author of the paper – explained via email:
“We applied a technique of image analysis developed by Mark Lemmon for use with the Mars Exploration Rovers that was adapted by John Moores for use on the Mars Phoenix lander mission. This analysis method allowed the faint, barely observable atmospheric features captured by the Huygens’ probe Side Looking Imager (SLI) on Titan to be amplified and more easily discerned.”
For years, scientists have understood that on Titan, methane is analogous to water. It exists in solid form, in liquid form (especially around the north pole where several large methane lakes exist), and in gaseous form in the atmosphere. However, what they did not know was whether or not there was an active cycle, where liquid methane on the surface was replenished through evaporation, condensation, and rain.
But this evidence, combined with the Cassini probe data, confirms that on Titan, there is active transfer process between the liquid methane and the atmospheric methane. And where atmospheric humidity reaches 100%, methane fogs will form. Just the latest in a long line of fascinating discoveries to emerge from this mysterious moon!
The post Huygens Data Confirms Presence Of Methane Fog At Titan’s South Pole appeared first on Universe Today.
Jupiter was appropriately named after the king of the gods. It’s massive, has a powerful magnetic field, and more moons that any planet in the Solar System. Though it has been known to astronomers since ancient times, the invention of the telescope and the advent of modern astronomy has taught us so much about this gas giant.
In short, there are countless interesting facts about this gas giant that many people just don’t know about. And we here at Universe Today have taken the liberty of compiling a list of ten particularly interesting ones that we think will fascinate and surprise you. Think you know everything about Jupiter? Think again!
1. Jupiter Is Massive:
It’s no secret that Jupiter is the largest planet in the Solar System. But this description really doesn’t do it justice. For one, the mass of Jupiter is 318 times as massive as the Earth. In fact, Jupiter is 2.5 times more massive than all of the other planets in the Solar System combined. But here’s the really interesting thing…
If Jupiter got any more massive, it would actually get smaller. Additional mass would actually make the planet more dense, which would cause it to start pulling it in on itself. Astronomers estimate that Jupiter could end up with 4 times its current mass, and still remain about the same size.
2. Jupiter Cannot Become A Star:
Astronomers call Jupiter a failed star, but that’s not really an appropriate description. While it is true that, like a star, Jupiter is rich in hydrogen and helium, Jupiter does not have nearly enough mass to trigger a fusion reaction in its core. This is how stars generate energy, by fusing hydrogen atoms together under extreme heat and pressure to create helium, releasing light and heat in the process.
This is made possible by their enormous gravity. For Jupiter to ignite a nuclear fusion process and become a star, it would need more than 70 times its current mass. If you could crash dozens of Jupiters together, you might have a chance to make a new star. But in the meantime, Jupiter shall remain a large gas giant with no hopes of becoming a star. Sorry, Jupiter!
3. Jupiter Is The Fastest Spinning Planet In The Solar System:
For all its size and mass, Jupiter sure moves quickly. In fact, with an rotational velocity of 12.6 km/s (~7.45 m/s) or 45,300 km/h (28,148 mph), the planet only takes about 10 hours to complete a full rotation on its axis. And because it’s spinning so rapidly, the planet has flattened out at the poles a little and is bulging at its equator.
In fact, points on Jupiter’s equator are more than 4,600 km further from the center than the poles. Or to put it another way, the planet’s polar radius measures to 66,854 ± 10 km (or 10.517 that of Earth’s), while its diameter at the equator is 71,492 ± 4 km (or 11.209 that of Earth’s). This rapid rotation also helps generate Jupiter’s powerful magnetic fields, and contribute to the dangerous radiation surrounding it.
4. The Clouds On Jupiter Are Only 50 km Thick:
That’s right, all those beautiful whirling clouds and storms you see on Jupiter are only about 50 km thick. They’re made of ammonia crystals broken up into two different cloud decks. The darker material is thought to be compounds brought up from deeper inside Jupiter, and then change color when they reacted with sunlight. But below those clouds, it’s just hydrogen and helium, all the way down.
5. The Great Red Spot has been around for a long time
The Great Red Spot on Jupiter is one of its most familiar features. This persistent anticyclonic storm, which is located south of its equator, measures between 24,000 km in diameter and 12–14,000 km in height. As such, it is large enough to contain two or three planets the size of Earth’s diameter. And the spot has been around for at least 350 years, since it was spotted as far back as the 17th century.
The Great Red Spot was first identified in 1665 by Italian astronomer Giovanni Cassini. By the 20th century, astronomers began to theorize that it was a storm, one which was created by Jupiter’s turbulent and fast-moving atmosphere. These theories were confirmed by the Voyager 1 mission, which observed the Giant Red Spot up close in March of 1979 during its flyby of the planet.
However, it appears to have been shrinking since that time. Based on Cassini’s observations, the size was estimated to be 40,000 km in the 17th century, which was almost twice as large as it is now. Astronomers do not know if or when it will ever disappear entirely, but they are relatively sure that another one will emerge somewhere else on the planet.
6. Jupiter Has Rings:
When people think of ring systems, Saturn naturally comes to mind. But in truth, both Uranus and Jupiter have ring systems of their own. Jupiter’s were the third set to be discovered (after the other two), due to the fact that they are particularly faint. Jupiter’s rings consist of three main segments – an inner torus of particles known as the halo, a relatively bright main ring, and an outer gossamer ring.
These rings are widely believed to have come from material ejected by its moons when they’re struck by meteorite impacts. In particular, the main ring is thought to be composed of material from the moons of Adrastea and Metis, while the moons of Thebe and Amalthea are believed to produce the two distinct components of the dusty gossamer ring.
This material fell into orbit around Jupiter (instead of falling back to their respective moons) because if Jupiter’s strong gravitational influence. The ring is also depleted and replenished regularly as some material veers towards Jupiter while new material is added by additional impacts.
7. Jupiter’s Magnetic Field Is 14 Times Stronger Than Earth’s:
Compasses would really work on Jupiter. That’s because it has the strongest magnetic field in the Solar System. Astronomers think the magnetic field is generated by the eddy currents – i.e. swirling movements of conducting materials – within the liquid metallic hydrogen core. This magnetic field traps particles of sulfur dioxide from Io’s volcanic eruptions, which producing sulfur and oxygen ions. Together with hydrogen ions originating from the atmosphere of Jupiter, these form a plasma sheet in Jupiter’s equatorial plane.
Farther out, the interaction of the magnetosphere with the solar wind generates a bow shock, a dangerous belt of radiation that can cause damage tos spacecraft. Jupiter’s four largest moons all orbit within the magnetosphere, which protects them from the solar wind, but also make the likelihood of establishing outposts on their surface problematic. The magnetosphere of Jupiter is also responsible for intense episodes of radio emission from the planet’s polar regions.
8. Jupiter Has 63 Moons:
As of the penning of this article, Jupiter has a 67 confirmed and named satellites. However, it is estimated that the planet has over 200 natural satellites orbiting it. Almost all of them are less than 10 kilometers in diameter, and were only discovered after 1975, when the first spacecraft (Pioneer 10) arrived at Jupiter.
However, it also has four major moons, which are collectively known as the Galilean Moons (after their discovered Galileo Galilei). These are, in order of distance from Jupiter, Io, Europa, Ganymede, and Callisto. These moons are some of the largest in the Solar System, with Ganymede being the largest, measuring 5262 km in diameter.
9. Jupiter Has Been Visited 7 Times By Spacecraft:
Jupiter was first visited by NASA’s Pioneer 10 spacecraft in December 1973, and then Pioneer 11 in December 1974. Then came the Voyager 1 and 2 flybys, both of which happened in 1979. This was followed by a long break until Ulysses arrived in February 1992. Then Cassini made a flyby in 2000, on its way to Saturn. And finally, NASA’s New Horizons spacecraft made its flyby in 2007. This was the last mission to fly past Jupiter, but it surely won’t be the last.
10. You Can See Jupiter With Your Own Eyes:
Jupiter is the third brightest object in the Solar System, after Venus and the Moon. Chances are, you saw Jupiter in the sky, and had no idea that’s what you were seeing. And here at Universe Today, we are in the habit of letting readers know when the best opportunities for spotting Jupiter in the night sky are.
Chances are, if you see a really bright star high in the sky, then you’re looking at Jupiter. Get your hands on a pair of binoculars, and if you know someone with a telescope, that’s even better. Using even modest magnification, you might even spot small specks of light orbiting it, which are its Galilean Moons. Just think, you’ll be seeing precisely what Galileo did when he gazed at the planet in 1610.
We have written many interesting articles about Jupiter here at Universe Today. Here’s The Gas Giant Jupiter, How Strong Is Jupiter’s Gravity?, Does Jupiter Have A Solid Core?, and Jupiter Compared To Earth.
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