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The Inner System Viewed from Saturn

With the Cassini mission continuing through 2017, we’ll doubtless have many fine views of Saturn to come, but the images below merit special attention, enough so that I decided to close the week with them. We’re looking at an annotated, panoramic mosaic made by processing 141 wide-angle images, sweeping across 651,591 kilometers. That covers the planet, its inner ring system and all its rings out to the E ring. Moreover, the view presented here is in natural color, so we see the color as it would be seen by human eyes rather than as distorted during observations at other wavelengths.


You may remember the ‘Wave at Saturn’ campaign from last summer, when the word went out that Cassini would be snapping a view of the Earth from Saturn space. In the mosaic (click the image to zoom in) we can see the Earth as a blue dot to the lower right of Saturn, but Venus is visible too to the upper left, and Mars shows up as the faint red dot above and to the left of Venus. A close look will reveal seven of Saturn’s moons, including the intriguing Enceladus to the left. Enceladus is worth mentioning because the E ring, about 240,000 kilometers from Saturn, is made up of fine icy particles from the erupting geysers in Enceladus’ south polar terrain.

“This mosaic provides a remarkable amount of high-quality data on Saturn’s diffuse rings, revealing all sorts of intriguing structures we are currently trying to understand,” said Matt Hedman, a Cassini participating scientist at the University of Idaho in Moscow. “The E ring in particular shows patterns that likely reflect disturbances from such diverse sources as sunlight and Enceladus’ gravity.”

The second image (below) has been brightened and color-enhanced to tease out the ring structure. Note the blue color of the E ring, which is caused by the diffraction of sunlight. In both images, the Earth, Venus, Mars, Enceladus, Epimetheus and Pandora were brightened by a factor of eight and a half relative to Saturn to make them easier to see, although you’ll still need to zoom in by clicking to make them out. The outer rings (from the G to the E ring) were likewise brightened relative to the already bright main rings. Full background on these images can be found on this JPL page.


Getting a view like this is tricky because trying to see the Earth from Saturn means looking close enough to the Sun to endanger sensitive spacecraft detectors. Thus the need to find a time when the Sun is entirely behind Saturn as seen from Cassini. The spacecraft’s wide-angle and narrow-angle cameras were used to capture 323 images in a little over four hours, with the red, green and blue spectral filters combined to create the natural-color view. Although this is the second time Cassini has viewed it, the Earth has only been imaged from the outer Solar System three times, the first being the famous ‘pale blue dot’ image from Voyager. This is also the first time Earth’s inhabitants were told in advance about a photo that would include their entire world.


Comments on this entry are closed.

  • ljk November 15, 2013, 12:24

    Explaining the details of this incredible image:


  • David Cummings November 15, 2013, 14:35

    Saturn is 1.2 billion km from Earth (at their closest pass) and a trip of that distance at New Horizons’ listed top speed of 45km/s would take 308 days.

    The same trip, at 1% the speed of light (3000km/sec) would take a little less than 5 days.

    What a difference a decent percentage of light speed makes!

    And how far out of our reach! (so far)

    1% of the speed of light is 67 times the top speed of New Horizons.

    What a way we have to go, not just to propel a craft to 1% of the speed of light, but to protect a craft at 1% of the speed of light.

    What happens to a probe smacking into a small rock at 3000km/sec?

    And even at that incredible speed, a probe to AC will take 420 years. That’s the meaning of distance in our galaxy, in our universe.

    If our sun were the size of a dot at the end of this sentence, the Milky Way Galaxy would be the size of the continental United States.

    Beautiful Saturn is both amazingly close to us… and agonizingly far away.

  • Alex Tolley November 15, 2013, 15:57

    The same trip, at 1% the speed of light (3000km/sec) would take a little less than 5 days. What a difference a decent percentage of light speed makes!

    I’ve… seen things you people wouldn’t believe… Attack ships on fire off the shoulder of Orion. I watched c-beams glitter in the dark near the Tannhäuser Gate. All those… moments… will be lost in time, like [coughs] tears… in… rain. Time… to die…

    If Roy Batty was a robot, not a android, we could beam his mind to a body waiting for him at Saturn. It would have taken a about 1.5 hours for the beam to reach Saturn from Earth, although he would feel as if the trip was instantaneous. A laser might burst for just a few seconds to carry the information in a robot brain as sophisticated as a human brain, at a tiny fraction of the cost of sending a physical spaceship. A robot could face the sun and “feel” its pale warmth on its skin. Will the conscious brains of such intelligences be the ones to stare at such sights in the future, effortlessly transferring themselves around the solar system on beams of light?

  • Andrew Palfreyman November 15, 2013, 22:37

    Let’s build some beamers close to the Sun and get a 100 Kg package from here to Saturn in mere days. We need a web of high power light beams criss-crossing the system for just such missions.

  • Enzo November 16, 2013, 1:56

    NASA, in the meantime, after having squandered all the plutonium left on Mars where solar panels work fine, has also cancelled the Stirling engine generator for good measure :

    With plutonium running out, there will be no missions beyond Jupiter for decades. So, enjoy these images because it’ll all we are going to get for a long while.

  • David Cummings November 16, 2013, 10:28

    A poignant moment in what remains one of the best SF movies of all time… and now nearly a third of a century old.

    I have never seen the HD version of that movie. Your reminder of that movie encourages me to do so this weekend. Thanks.

  • Michael November 16, 2013, 15:28

    Saturn is not called ‘Lord of the Rings’ for nothing.

  • ljk January 14, 2014, 9:31


    13 January 2014

    The planet Venus is blanketed by high-level clouds. At visible wavelengths, individual cloud features are difficult to see, but observations made by instruments on ESA’s Venus Express orbiter have revealed many small-scale wave trains.

    Analysis shows that the waves are mostly found at high northern latitudes, particularly above Ishtar Terra, a continent-sized region that includes the highest mountains on the planet.

    Full article here:


  • ljk January 15, 2014, 23:29

    Will we Build Colonies that Float Over Venus like Buckminster Fuller’s “Cloud Nine”?

    By Robert Walker | January 12th 2014 09:02 AM

    This idea dates back to the Russians in the 1970s. The surface of Venus is far too hot, and the atmosphere too dense, for Earth life. However, our air is a lifting gas on Venus with about half the lifting power of helium on Eath. A habitat filled with normal air will float high in the dense Venus atmosphere, The atmospheric pressure there is the same as Earth sea level (1 bar). Temperatures are perfect for Earth life too, just over 0°C.

    Also, just as weather balloons naturally rise to their operating level high in our atmosphere – and don’t need to be engineered to hold in high pressures, so it works in the same way for our habitats on Venus. They float at a level where the pressure is equal inside and out, and can be of light construction. It is arguably the most hospitable region for humanity in our solar system, outside of Earth itself.

    Venus cloud colony habitats can draw on our experience of buildings for the Earth surface, especially Buckminster fuller type lightweight domes. In this way, humans perhaps could colonize floating colonies just at the tops of the clouds of Venus. The surface of Venus is harsh in the extreme, way outside the range of habitability for any known form of Earth life. However, the environment at the cloud tops is surprisingly habitable.

    Full article here:


  • ljk January 18, 2014, 22:43


    Researcher finds convincing evidence for water molecules inside Venus.

    Originally published: Jan 17 2014 – 4:45pm

    By: Jessica Orwig, ISNS Contributor

    (ISNS) — In 2010, the European Space Agency’s Venus Express orbiter observed that twice as many hydrogen atoms as oxygen atoms were escaping from Venus into space. This was the first evidence that Venus might once have harbored puddles, pools and even lakes of liquid water on its surface. Now, a new study suggests that Venus could be storing some amount of intact water molecules within its mantle.

    To determine this, Justin Filiberto, a geologist at Southern Illinois University in Carbondale, compared what geologists know about the composition of rocks on the surface of Venus with rock formation processes here on Earth. His results, which appeared in the December issue of the journal ICARUS, suggest that some types of rocks on Venus could only have formed in the presence of water and carbon dioxide.

    Between 1981 and 1984, the USSR launched six missions to Venus. Three of those missions, Venera 13 and 14 and Vega 2, compiled what today remains the most complete chemical composition analyses of rock and soil on Earth’s sister planet.

    The Venera and Vega probes landed at different points on the surface and each used a robotic drilling arm to collect samples of rock and soil. The samples are representative of the three main types of terrain on Venus. Venera 13 collected samples from the planet’s rolling upland plains, which cover about 70 percent of the surface, and Venera 14 sampled rock from flat lowlands, which comprise 20 percent of the surface. About ten percent of the surface is mountainous terrain. Vega 2 landed at one of those regions, known as Aphrodite Terra.

    Onboard instruments then analyzed the samples’ chemical makeup before the probes melted and crumbled under Venus’ extreme temperatures and pressures–but not before they first relayed the data to Earth describing the percentage, by weight, of chemical compounds like titanium dioxide and silicon dioxide.

    Although geologists determined that all of the rock samples were igneous, meaning they formed from the cooling and solidification of magma or lava, the data lacked some important information. For example, the total weight of the rock samples from the Vega 2 analyses adds up to 89.6 percent, suggesting that the analyses are missing some elements.

    Moreover, the probes were unable to analyze certain elements like sodium, which is a crucial ingredient for classifying types of igneous rocks on Earth. Without this piece of the puzzle, there is no guarantee they can accurately deduce the conditions under which the rocks formed, or develop a better understanding of volcanic activity in the mantle of Venus.

    Geologists do know, however, what kind of role sodium and other elements like magnesium and silicon play in the formation of igneous rocks on Earth. And using a process called crystallization, geologists can determine the kinds of pressure, temperature and water conditions of the magma that produce the many different types of igneous rocks on Earth and the weight percentages of different elements produced as a result. Using this information about Earth rocks as an analog, Filiberto set constraints on the different pressure, temperature and water conditions that Venus rocks might have formed under.

    Depending on its location in Earth’s mantle, magma contains different constituents such as dissolved carbon dioxide or hydrous minerals, minerals with water molecules incorporated into their molecular structures. Filiberto found that the Venera 14 and Vega 2 samples contained crystal structures much like basalts on Earth that formed from hydrous sources near the upper mantle, where pressure is lower.

    Venera 13 samples, on the other hand, likely formed at higher pressures, deep within the planet’s mantle, from magma rich in carbon dioxide. This is the first study to show that rocks on Venus formed under different pressures at different depths of the planet, Filiberto said.

    “This is a new conclusion about the constraints on the water and carbon dioxide contents of the magmas,” Filiberto said. “And it shows that the interior of Venus is not just Earth-like in bulk chemistry but in water and carbon dioxide as well.”

    While the study shines more light on the geological story of Venus, the results are limited by the thirty-year-old, incomplete data, said Greg Shellnutt, who is a geochemist at the National Taiwan Normal University and also studies the geological origins of Venusian rocks.

    “This could be very exciting results but there are still so many unknowns. We’ve reached the limit of our data,” Shellnutt said, “but we’re doing the best with the data we have to work with.”

    Both Shellnutt and Lori Glaze, Deputy Director of NASA’s Solar System Exploration Division, agree that confirming results like Filiberto’s will require dispatching the first Venus lander of the 21st century. Glaze said that for her work on conceptualizing future Venus missions, the most important points in Filiberto’s paper are his models. The models detail what type of information is still needed in the different regions on Venus. These include, for example, the rocks’ sodium, magnesium and silicon contents, at any point on the surface of Venus, to understand the rocks’ origins.

    “This type of work in Justin Filiberto’s paper helps to better define what kind of instruments and what types of sensitivity we need to make when we go back to the surface,” Glaze said. “One of the key ways to get at the surface history of Venus is to land there and do a better job of the chemistry analyses.”

    Such a mission would paint geologists a more complete picture of a long-lost Venus when large amounts of liquid water may have adorned its surface. Moreover, determining if water or carbon dioxide is a dominant presence in magma is important for understanding Venus’ climate evolution and atmospheric chemistry, Filiberto said.

    Jessica Orwig is a contributing writer to Inside Science News Service.

  • ljk February 6, 2014, 12:15

    Forty years ago, February 5, 1974, the space probe Mariner 10 flew by the planet Venus and returned the first images from the vicinity of that world while also performing the first gravity assist to another world, in this case Mercury:


  • ljk March 18, 2014, 12:14


    Active Volcanoes Revealed on Venus

    MAR 17, 2014 09:10 AM ET // BY IRENE KLOTZ

    Scientists have long suspected that volcanoes played a huge role in the evolution of cloud-shrouded Venus, the second planet from the sun.

    Now, images from Europe’s Venus Express orbiter are showing that volcanic eruptions may not just be a thing from the past.

    Scientists discovered four transient bright spots in a relatively young rift zone known as Ganiki Chasma, which was observed 36 times by the spacecraft’s Venus Monitoring Camera.

    “Venus might have ongoing volcanism,” planetary scientist Alexander Bazilevskiy, with the Max-Planck Institute for Solar System Research in Germany, said at the Lunar and Planetary Science Conference in Houston on Monday.

    Bazilevskiy and colleagues constructed mosaics from images taken during the orbital passes and computed the relative surface brightness.

    They found four transient flashes, estimated to be between 980 degrees and 1,520 degrees Fahrenheit – well above the planet’s normal 800 degree Fahrenheit surface temperature.

    The Metallic Snows of Venus

    “We were looking for these spots for several years (and) didn’t find,” anything, Bazilevskiy said.

    He and colleagues figured the chance of seeing anything was extremely slim, just about 8 percent.

    “Then we found something,” Bazilevskiy said.

    Four places, actually, all near Maat Mons, a giant shield volcano on Venus that scientists believe last erupted 10 million to 20 million years ago.

    “Geologically, it’s like yesterday,” Bazilevskiy said.

    Follow-up analysis suggests the bright flashes could be lava flows stretching 16 miles or so, a chain of cinder cones, or a volcanic hotspot similar to what has been found on Jupiter’s volcanically active moon Io.

    Scientists plan to comb through archived radar images of Venus made with NASA’s Magellan spacecraft between 1990 and 1994 to see if they can find any other evidence of potential volcanic activity.

    The team also is continuing to use the eight-year-old Venus Express spacecraft to look for flashes in other rift zones.

    In a synopsis of the research, lead author Eugene Shalygin, also with the Max-Planck Institute, wrote that the discovery of present-day volcanic activity on Venus would have “major implications” for understanding processes in the planet’s interior, surface and atmosphere.

  • ljk March 24, 2014, 12:59

    If at first you don’t succeed… (part 1)

    The early history of Soviet missions to Venus and Mars was filled with failures. Andrew LePage looks back at how Soviet engineers responded to the initial set of failed missions with a spacecraft concept designed for missions to both planets.

    Monday, March 24, 2014