The Cassini spacecraft was sent by NASA and ESA to study Saturn and its moons. Two of Saturn’s moons, Enceladus and Tethys, appear in the bottom right of this image. So far, the spacecraft has found new storm systems on Saturn, active geysers on its moon Enceladus, liquid oceans on its moon Titan, and many other unexpected discoveries. Due to its elliptical orbit, Cassini is occasionally able to catch beautyful images of saturn backlit by our sun, as seen above.
Moons and some rings of Saturn, photographed by Cassini, 1 June 2004. Enceladus is the largest moon seen here (the four diffraction spikes from the narrow-angle camera are unusually clear). Prometheus sneaks into a couple of frames at the end, just inside the F Ring. Outside the F Ring are the co-orbital moons Janus and Epimetheus, and I’ve chosen the end-point of the gif so that one loops almost seamlessly into the other.
Earth isn’t the only planet in the solar system with spectacular light shows. Both Jupiter and Saturn have magnetic fields much stronger than Earth’s. Auroras also have been observed on the surfaces of Venus, Mars and even on moons (e.g. Io, Europa, and Ganymede). The auroras on Saturn are created when solar wind particles are channeled into the planet’s magnetic field toward its poles, where they interact with electrically charged gas (plasma) in the upper atmosphere and emit light. Aurora features on Saturn can also be caused by electromagnetic waves generated when its moons move through the plasma that fills the planet’s magnetosphere. The main source is the small moon Enceladus, which ejects water vapor from the geysers on its south pole, a portion of which is ionized. The interaction between Saturn’s magnetosphere and the solar wind generates bright oval aurorae around the planet’s poles observed in visible, infrared and ultraviolet light. The aurorae of Saturn are highly variable. Their location and brightness strongly depends on the Solar wind pressure: the aurorae become brighter and move closer to the poles when the Solar wind pressure increases.
EUROPA Scientists expect that Europa may have more liquid water than in all of Earth’s oceans. It has all the elements thought to be key for the origin of life: water, energy, and organic chemicals, the carbon-containing building blocks of life. Unlike Earth though, Europa’s vast, salty seas lie beneath roughly 10 miles of ice. Not only is it difficult to get a probe beneath this icy armor, but Europa’s oceans are darker than a cave — which means photosynthesis won’t work. However, something down there may subsist on geothermal heat or complex molecules from the surface. http://bit.ly/1trVzvX
NASA says it’s setting aside $25 million for designing scientific instruments to address questions about the habitability of Europa, an ice-covered moon of Jupiter. A Europa probe that could be launched in the 2020s. http://nbcnews.to/1pU2JJe
TITAN Titan is Saturn’s largest moon and the only world in the solar system (besides Earth) known to sport liquid lakes. These are lakes of ethane and methane — liquid natural gas — endlessly topped up by hydrocarbon rain. Despite the odd ingredients and Titan’s extremely cold temperatures (minus 290 Fahrenheit, or minus 179 Celsius), it is a world where chemistry’s a happening enterprise. It’s so cold that water ice is rock-hard—in fact, the rocks littering the moon’s surface are made from water. Water is everywhere on Titan, but it’s locked in a state that’s inaccessible for life-sustaining chemistries. On Titan, scientists would most likely be looking for bizarre life. Life that, instead of being water-based, uses liquid hydrocarbons as a solvent. Yet if life is found, it could demonstrate a different way in which it could begin and populate the cosmos.
CALLISTO Like its more celebrated neighbor Europa, scientists suggest that Callisto’s interior contains a salty ocean separated by ice layers, with a rocky seafloor underlying everything. The likely presence of an ocean within Callisto leaves open the possibility that it could sustain life. Because of its low radiation levels, Callisto has long been considered a suitable place among the Galilean moons for future exploration. http://bit.ly/1pra4Qx
GANYMEDE The largest moon in the solar system, Ganymede, may feature liquid oceans layered between vast sheets of ice. Studies suggest that there may be a layer of salty water directly on top of Ganymede’s rocky core. Chemical interactions between rock and water could lead to the formation of life. http://cnn.it/1q8jCj2
VENUS Venus, with its scorching surface temperatures (850 F, or 454 C). The planet is generally assumed to be unlivable but some scientists believe that high in the Venusian atmosphere where temperatures are more tolerable atmospheric sulfur dioxide and carbon monoxide might serve as food for floating microbes. http://bit.ly/1l3sWVo
MARS Mars remains popular for those hunting for otherworldly life. In 2013, scientists identified sulfur, nitrogen, hydrogen, oxygen, phosphorus and carbon - some of the key chemical ingredients for life - in the powder Curiosity drilled out of a sedimentary rock near an ancient stream bed in Gale Crater. Also, particularly intriguing are the dark stripes that appear in the Martian summertime at Horowitz crater. These are likely to be salty meltwater only inches beneath Mars’ dusty top layer.
ENCELADUS In 2005, NASA’s Cassini spacecraft photographed geysers of frozen water spewing from cracks in Enceladus’ southern hemisphere. Scientists think reservoirs of liquid water lie beneath the frozen surface and are warmed by gravitational interactions between Enceladus and other moons around Saturn. http://bit.ly/1pZu0bf
This is a photo of Saturn’s moon Enceladus - a dynamic ice world. Its surface shifts on geologic timescales, with vast ice sheets spreading and crashing like tectonic plates. Cryovolcanoes (which is a real term that I did not make up) shoot geysers of water out into space.
Recent readings taken by the Cassini spacecraft suggest that Enceladus has a rocky core and liquid oceans beneath the icy surface.
This picture was taken as Cassini was speeding away from Enceladus in 2008, after skimming just 15 miles above its surface.
Saturn’s bright satellite Enceladus is covered with water ice that reflects almost all the Sun’s light back into space.
The geologically active moon, discovered in 1789 by William Herschel, has craters, ridges and smooth plains. Most spectacularly, Enceladus has geysers that spew frozen water thousands of kilometres into space.
In the Greek Mythology Mount Etna’s eruptions were said to be the breath of Enceladus, a giant buried under the volcano, and its tremors to be caused by him rolling over from side to side beneath the mountain. A Saturn’s moon was named after it. I experienced this shooting it exactly between the myth and the outer space trip.
Saturn’s moon Rhea is in the centre of the frame, as two moons move past it. Mimas is the (apparently) slower-moving moon; Enceladus moves more rapidly through the field of view. Photographed by Cassini, 27 January 2006.
It has been suspected for a long time that under Enceladus’ icy crust laid a vast ocean. Finally, the news we were waiting for: the Cassini orbiter has detected signals of a hidden ocean beneath the 19 to 25 miles (30 – 40 km) of ice. The sea itself is at least 6 miles (10 km) deep and can be thought of as a larger Lake Superior.
Enceladus has also been known to have geysers, similar to those recently discovered on Europa, which contain salts as well as organic molecules such as methane and ethane. What’s interesting is that Enceladus experiences tidal flexing as it orbits Saturn. This flexing is thought to generate heat at the poles. Furthermore, scientists believe that there’s enough heat at the South Pole to melt the ice and push the seawater up to the various cracks in the surface. This is very exciting for astrobiologists because it means that the sea could be in contact with organic-rich silicate material from the moon’s internal rocky core, which is just at the right temperature for sustaining life. This discovery is truly setting the stage for the future and it makes a compelling case to study Enceladus in more detail.
Show your support for NASA, so that we can send more orbiters and uncover the amazing mysteries waiting for us. Tell Congress it’s time we give a Penny4NASA. Take action today by heading over to http://www.penny4nasa.org/take-action/
The photos Cassini has been sending back go beyond science. They are art.
In this image, Titan can be seen behind Saturn’s rings with Enceladus peaking onto the crescent. The bright surrounding ring is atmospheric haze above Titan, gas that is scattering sunlight to a camera operating onboard the robotic Cassini spacecraft. Since the image was taken pointing nearly at the Sun, the surfaces of Titan and Enceladus appear in silhouette, and the rings of Saturn appear similar to a photographic negative.
(Image Credit: Cassini Imaging Team, SSI, JPL, ESA, NASA)
Why is Saturn partly blue? The above picture of Saturn approximates what a human would see if hovering close to the giant ringed world. The above picture was taken in mid-March by the robot Cassini spacecraft now orbiting Saturn. Here Saturn’s majestic rings appear directly only as a thin vertical line. The rings show their complex structure in the dark shadows they create on the image left. Saturn’s fountain moon Enceladus, only about 500 kilometers across, is seen as the bump in the plane of the rings. The northern hemisphere of Saturn can appear partly blue for the same reason that Earth’s skies can appear blue – molecules in the cloudless portions of both planet’s atmospheres are better at scattering blue light than red. When looking deep into Saturn’s clouds, however, the natural gold hue of Saturn’s clouds becomes dominant. It is not known why southern Saturn does not show the same blue hue – one hypothesis holds that clouds are higher there. It is also not known why Saturn’s clouds are colored gold.
Enceladus is a moon of Saturn that is believed to have an ocean under its surface. As pictured above, Enceladus has giant plumes. These plumes contain water vapor, carbon dioxide, and various trace compounds like ammonia. The geysers can erupt up to 3x the radius of Enceladus itself, suggesting the interior is rather warm.
This is a fantastic place to search for life! There could be life forms under the ice. Similarly to Earth, there could be life thriving on the extreme conditions at the bottom of the ocean.
Hidden Ocean Found on Saturn’s Icy Moon Enceladus, Could Potentially Support Life
The Saturn moon Enceladus harbors a big ocean of liquid water beneath its icy crust that may be capable of supporting life as we know it, a new study reports.
The water ocean on Enceladus is about 6 miles (10 kilometers) deep and lies beneath a shell of ice 19 to 25 miles (30 to 40 km) thick, researchers said. Further, it’s in direct contact with a rocky seafloor, theoretically making possible all kinds of complex chemical reactions — such as, perhaps, the kind that led to the rise of life on Earth.
Saturn, photographed by Cassini, 20-21 July 2009. The two large moons in the top-left are Enceladus and Tethys; Mimas makes a fleeting appearance in the lower-right; and if you watch carefully, you can see Epimetheus and Janus just outside the F Ring.