Earth and Moon imaged from Cassini on July 19, 2013
Did you smile and wave at Saturn on Friday? If you did (and even if you didn’t) here’s how you — and everyone else on Earth — looked to the Cassini spacecraft, 898.4 million miles away.
Hope you didn’t blink!
The image above is a color-composite made from raw images acquired by Cassini in red, green, and blue visible light wavelengths. Some of the specks around the edges are background stars, and others are the result of high-energy particle noise, of which some have been digitally removed.
The Moon is the bright dot just below and to the left of Earth. (An original raw image can be seen here.)
Cassini acquired the images while capturing views of Saturn in eclipse against the Sun between 22:24:00 UTC on July 19 and 02:43:00 UTC on July 20 (6:24 to 10:43 pm EDT July 19.) On Cassini time, the Earth imaging took place between 22:47:13 UTC (6:47:13 pm EDT) and 23:01:56 UTC (7:01:56 pm EDT) on the 19th.
Full mosaic arrangement acquired by Cassini on July 19-20 UTC. Earth was positioned just below the planet. (NASA/JPL-Caltech/SSI)
The world was invited to “Wave at Saturn” beginning 5:27 pm EDT on Friday — which allowed enough time for the photons from a waving world to actually reach Cassini’s camera just beyond Saturn, 1.44 billion kilometers away. (Did you wave? I did!) It was the first time Earth’s population was made aware beforehand that their picture would be taken from such a cosmic distance.
A crowd gathered on the mall at NASA’s Jet Propulsion Laboratory in Pasadena to wave at Saturn on July 19 (NASA/JPL-Caltech)
The image of our planet and moon, seen as merely a couple of bright points of light against the blackness of space, recalls Sagan’s poignant “pale blue dot” passage from Cosmos…
“From this distant vantage point, the Earth might not seem of any particular interest. But for us, it’s different. Consider again that dot. That’s here, that’s home, that’s us. On it everyone you love, everyone you know, everyone you ever heard of, every human being who ever was, lived out their lives. The aggregate of our joy and suffering, thousands of confident religions, ideologies, and economic doctrines, every hunter and forager, every hero and coward, every creator and destroyer of civilization, every king and peasant, every young couple in love, every mother and father, hopeful child, inventor and explorer, every teacher of morals, every corrupt politician, every “superstar,” every “supreme leader,” every saint and sinner in the history of our species lived there – on a mote of dust suspended in a sunbeam.
The “pale blue dot” of Earth captured by Voyager 1 in Feb. 1990 (NASA/JPL)
The Earth is a very small stage in a vast cosmic arena. Think of the rivers of blood spilled by all those generals and emperors so that, in glory and triumph, they could become the momentary masters of a fraction of a dot. Think of the endless cruelties visited by the inhabitants of one corner of this pixel on the scarcely distinguishable inhabitants of some other corner, how frequent their misunderstandings, how eager they are to kill one another, how fervent their hatreds.
Our posturings, our imagined self-importance, the delusion that we have some privileged position in the universe, are challenged by this point of pale light. Our planet is a lonely speck in the great enveloping cosmic dark. In our obscurity, in all this vastness, there is no hint that help will come from elsewhere to save us from ourselves.
The Earth is the only world known so far to harbor life. There is nowhere else, at least in the near future, to which our species could migrate. Visit, yes. Settle, not yet. Like it or not, for the moment the Earth is where we make our stand.
It has been said that astronomy is a humbling and character-building experience. There is perhaps no better demonstration of the folly of human conceits than this distant image of our tiny world. To me, it underscores our responsibility to deal more kindly with one another, and to preserve and cherish the pale blue dot, the only home we’ve ever known.”
— Carl Sagan (1934–1996)
A full mosaic of Cassini’s imaging of Saturn silhouetted against the Sun is expected in the coming weeks.
UPDATE: Here’s another RGB color composite, made from raw images acquired with Cassini’s wide-angle camera. It shows a view of Saturn and the rings in eclipse as seen from below and behind, backlit by the Sun. Earth is the bright point light near the center. (See original here.)
Raw image (RGB composite) of Saturn in eclipse with Earth in the distance — just a pale blue dot. (NASA/JPL-Caltech/SSI. Composite by J. Major.)
Images: NASA/JPL-Caltech/Space Science Institute. Composites by Jason Major.
Just one of the many images from Cassini used to make up "Around Saturn"
In honor of this today’s Wave at Saturn and The Day the Earth Smiled events, celebrating images to be taken of Earth from Saturn, here’s a wonderful movie showing highlights from Cassini’s exploration of the giant planet, its magnificent rings, and fascinating family of moons.
Assembled by Fabio Di Donato in memory of astrophysicist, author and activist Margherita Hack, who passed away June 29 at the age of 91, this video is an impressive tour of the Saturnian system — and a truly stunning tribute as well.
“She made me love the stars,” Fabio wrote.
This video shows a selection from more than 200,000 pictures taken by the Cassini spacecraft around Saturn’s rings in a period between 2005 and 2013. RAW images were processed to PNG thanks to the Vicar-to-PNG procedure provided by Jessica McKellar.
The music is Jazz Suite No.2: VI Waltz 2 by Shostakovich, performed by the Armonie Symphony Orchestra.
As always, you can see the latest images and news from the Cassini mission here, and find out how your photo is going to be taken from 900 million miles away (and also 60 million miles away from Mercury!) here.
Video: Fabio Di Donato. Original images: NASA/JPL-Caltech/SSI.
P.S.: Want to get a personalized certificate saying you “Waved at Saturn?” Click here.
A look at what Cassini's point of view will be at the time of the #WaveAtSaturn event. Image courtesy Mike Smithwick and Distant Suns.
You’ve hopefully heard about the chance to have your picture taken this Friday – along with the rest of humanity – by the Cassini spacecraft, currently about 1 billion km away as it orbits Saturn. But now another spacecraft has joined in on the fun.
Inspired in part by the Cassini team, scientists from the MESSENGER mission at Mercury realized their upcoming orbital parameters has Earth coincidentally in the crosshairs of its cameras as it takes images to search for natural satellites around Mercury on July 19 and 20. So we’ve got not one, but TWO spacecraft to smile at, pose for, and generally be on good behavior as they take pictures of planet Earth. Here’s when you should be smiling and waving:
MESSENGER will be taking images at 11:49, 12:38, and 13:41 UTC (4:49 a.m., 5:38 a.m. and 6:41 a.m. PDT or 7:49 a.m., 8:38 a.m. and 9:41 a.m. EDT, or) on both days, July 19 and 20. Parts of Earth not illuminated in the Cassini images, including all of Europe, the Middle East and Central Asia, will appear illuminated in the MESSENGER images. MESSENGER’s images also will take a few days to process prior to release, the team said.
The image taken from the Saturn system by NASA’s Cassini spacecraft will occur between 21:27 and 21:47 UTC (2:27 and 2:42 PDT, 5:27 and 5:42 p.m. EDT) on Friday, July 19. Cassini will be nearly 900 million miles (nearly 1.5 billion kilometers) away from Earth. NASA is encouraging the public to look and wave in the direction of Saturn at the time of the portrait and share their pictures via the Internet.
The ‘Wave at Saturn” event will be the first time Earthlings have had advance notice that their picture will be taken from interplanetary distances. Credit: NASA/JPL-Caltech
Also, at the exact time the Cassini spacecraft is snapping pics of Earth, the Slooh Space Camera will be snapping images of Saturn – live and in true color – with live broadcast team. Their feed starts at 2:30 PM PDT / 5:30 PM EDT / 21:30 UTC with live views of Saturn from the Canary Islands.
Astronomers Without Borders is also sponsoring a special Saturn Observing Program, and they are encouraging people and organizations to either organize a special observing event for July 19 (you can register it as an official event here) or to attend an event near you. You can find TDTES events here. This can be a full-blown observing event with telescopes, or just an excuse to get together with friends to go out and look at Saturn in the night sky.
This graphic shows the view of Earth and the portion of its surface that will be illuminated during the Earth imaging event by the Cassini spacecraft on July 19, 2013. Credit: NASA/JPL-Caltech.
July 19, 2013 will be a day that we should really all try to get along. Isn’t that a noble goal? And you can be a part of it in several different ways. In a special project, the Cassini spacecraft will be taking an image of Earth, from the spacecraft’s orbit around Saturn. Specifically, Cassini will be on the far side of Saturn when it snaps a picture of “us” between 21:27 to 21:42 UTC (5:27-5:42 pm EDT.) Cassini will be in just the right spot that it can “see” Earth, but Saturn will be blocking the glare from the Sun. There will likely be a dramatic view of Saturn and its rings in the foreground, with Earth off in the distance. Our home planet won’t be much more than a few pixels in the image, but it will be “us, …everyone you love, everyone you know, everyone you ever heard of, every human being who ever was,” as Carl Sagan said about the Pale Blue Dot image taken by the Voyager spacecraft.
“It will be a day to revel in the extraordinary achievements in the exploration of our solar system that have made such an interplanetary photo session possible,” said Cassini imaging team leader Carolyn Porco of the Space Science Institute, who had the idea for this special image. “And it will be a day for all of us to smile and celebrate life on the Pale Blue Dot.”
First, while Earth has been imaged before from other distant spacecraft (the famous Pale Blue Dot image and Cassini has taken pictures of Earth before) this is the first time that many of the inhabitants of Earth will know the image is being taken – hence the invitation to smile and wave.
Second, Saturn is now visible in the night sky — bright and shining — allowing us a direct line of sight to smile and wave back. No, we can’t see Cassini, but we know it’s there!
Plus, there’s other special chances to submit your own images – of Saturn, and of Earth, or of yourself in the moments Cassini is taking the image.
Astronomers Without Borders is also sponsoring a special Saturn Observing Program, and they are encouraging people and organizations to either organize a special observing event for July 19 (you can register it as an official event here) or to attend an event near you. You can find TDTES events here. This can be a full-blown observing event with telescopes, or just an excuse to get together with friends to go out and look at Saturn in the night sky.
Mosaic of Saturn seen in eclipse in September 2006. Earth is the bright dot just inside the F ring at upper left. (CICLOPS/NASA/JPL-Caltech/SSI)
Citizens of Earth, get ready for your Cassini close-up: once again the spacecraft is preparing to capture images of Saturn positioned between it and the Sun, allowing for incredible views of the ring system and its atmosphere — and also a tiny “pale blue dot” in the distance we call home.
Earth seen from Cassini (NASA/JPL/SSI)
The mosaic above was composed of images captured during such an eclipse event in September 2006, and quickly became an astronomical sensation. It’s not often we get an idea of what we look like from so far away, and seeing our entire world represented as a small speck of light nestled between Saturn’s rings is, to me anyway, both impressive and humbling.
Humbling because of how small we look, but impressive because as a species we have found a way to do it.
And next month, on Friday, July 19 between 21:27 and 21:42 UTC (5:27 – 5:42 p.m. EDT) Cassini will do it again.
“Ever since we caught sight of the Earth among the rings of Saturn in September 2006 in a mosaic that has become one of Cassini’s most beloved images, I have wanted to do it all over again, only better,” said Cassini imaging team leader, Carolyn Porco. “And this time, I wanted to turn the entire event into an opportunity for everyone around the globe, at the same time, to savor the uniqueness of our beautiful blue-ocean planet and the preciousness of the life on it.”
Porco was involved in co-initiating and executing the famous “Pale Blue Dot” image of Earth taken by NASA’s Voyager 1 from beyond the orbit of Neptune in 1990.
“It will be a day for all the world to celebrate,” she said.
The intent for the upcoming mosaic is to capture the whole scene, Earth and Saturn’s rings from one end to the other, in Cassini’s red, green and blue filters that can be composited to form a natural color view of what our eyes might see at Saturn. Earth and the Moon will also be imaged with a high resolution camera — something not yet done by Cassini.
We can all consider ourselves pretty lucky, too… this is the first time in history that we humans will know in advance that our picture is going to be taken from nearly a billion miles away.
“While Earth will be only about a pixel in size from Cassini’s vantage point 898 million miles [1.44 billion kilometers] away, the Cassini team is looking forward to giving the world a chance to see what their home looks like from Saturn,” said Linda Spilker, Cassini project scientist at NASA’s Jet Propulsion Laboratory. “With this advance notice, we hope you’ll join us in waving at Saturn from Earth, so we can commemorate this special opportunity.”
So on July 19, remember to look up and wave… Cassini will be watching!
Read more on the CICLOPS news release here and on the NASA/JPL Cassini mission site here.
“That’s here. That’s home. That’s us. On it everyone you love, everyone you know, everyone you ever heard of, every human being who ever was, lived out their lives… There is perhaps no better demonstration of the folly of human conceits than this distant image of our tiny world.”
Long-exposure Cassini NAC image of Saturn's D ring system (NASA/JPL-Caltech/SSI)
The closest to the planet itself, the hazy arcs of Saturn’s D ring may lack the reflective brilliance and sharply-defined edges of the other main rings, but they nevertheless possess their own ethereal beauty and mysteries. Here, the Cassini spacecraft has managed to capture the soft bands of the D ring in a long-exposure image acquired on April 2, 2013 — so long an exposure, in fact, that background stars seen through the rings appear as long vertical streaks, a testament to the ring’s dimness as well as the spacecraft’s continuing movement.
Beginning 8,768 km (5,448 miles) above the tops of Saturn’s clouds, the D ring is the innermost and thinnest segment of Saturn’s main ring system. Nearly transparent, the D ring extends about 7,500 km (4,660 miles) before transitioning to the considerably brighter C ring, which is over twice as wide.
The innermost portion of the C ring can be seen above along the left side. Saturn’s shadow blankets the lower right corner.
The cause of the alternating light-and-dark bands observed within the D ring isn’t yet known, but they may be the result of an impact by a comet or large meteor that set up recurring waves of material.
The view was acquired at a distance of approximately 510,000 kilometers (317,000 miles) from Saturn and at a phase angle of 147 degrees. Image scale is 2 miles (3 kilometers) per pixel.
From a distance, most of the Saturnian moon Dione resembles a bland cueball. Thanks to close-up images of a 500-mile-long (800-kilometer-long) mountain on the moon from NASA’s Cassini spacecraft, scientists have found more evidence for the idea that Dione was likely active in the past. It could still be active now.
“A picture is emerging that suggests Dione could be a fossil of the wondrous activity Cassini discovered spraying from Saturn’s geyser moon Enceladus or perhaps a weaker copycat Enceladus,” said Bonnie Buratti of NASA’s Jet Propulsion Laboratory in Pasadena, Calif., who leads the Cassini science team that studies icy satellites. “There may turn out to be many more active worlds with water out there than we previously thought.”
Janiculum Dorsa, a mountain that appears as the long, raised scar in the middle of this Cassini image, is providing new evidence that the Saturnian moon Dione was recently active. Credit: NASA/JPL-Caltech/Space Science Institute.
Other bodies in the solar system thought to have a subsurface ocean – including Saturn’s moons Enceladus and Titan and Jupiter’s moon Europa – are among the most geologically active worlds in our solar system. They have been intriguing targets for geologists and scientists looking for the building blocks of life elsewhere in the solar system. The presence of a subsurface ocean at Dione would boost the astrobiological potential of this once-boring iceball.
Hints of Dione’s activity have recently come from Cassini, which has been exploring the Saturn system since 2004. The spacecraft’s magnetometer has detected a faint particle stream coming from the moon, and images showed evidence for a possible liquid or slushy layer under its rock-hard ice crust. Other Cassini images have also revealed ancient, inactive fractures at Dione similar to those seen at Enceladus that currently spray water ice and organic particles.
The mountain examined in the latest paper — published in March in the journal Icarus — is called Janiculum Dorsa and ranges in height from about 0.6 to 1.2 miles (1 to 2 kilometers). The moon’s crust appears to pucker under this mountain as much as about 0.3 mile (0.5 kilometer).
The topography of a mountain known as Janiculum Dorsa on the Saturnian moon Dione. Color denotes elevation, with red as the highest area and blue as the lowest. Credit: NASA/JPL-Caltech/Space Science Institute.
“The bending of the crust under Janiculum Dorsa suggests the icy crust was warm, and the best way to get that heat is if Dione had a subsurface ocean when the ridge formed,” said Noah Hammond, the paper’s lead author, who is based at Brown University, Providence, R.I.
Dione gets heated up by being stretched and squeezed as it gets closer to and farther from Saturn in its orbit. With an icy crust that can slide around independently of the moon’s core, the gravitational pulls of Saturn get exaggerated and create 10 times more heat, Hammond explained. Other possible explanations, such as a local hotspot or a wild orbit, seemed unlikely.
Scientists are still trying to figure out why Enceladus became so active while Dione just seems to have sputtered along. Perhaps the tidal forces were stronger on Enceladus, or maybe the larger fraction of rock in the core of Enceladus provided more radioactive heating from heavy elements. In any case, liquid subsurface oceans seem to be common on these once-boring icy satellites, fueling the hope that other icy worlds soon to be explored – like the dwarf planets Ceres and Pluto – could have oceans underneath their crusts. NASA’s Dawn and New Horizons missions reach those dwarf planets in 2015.
A dense network of small rivers or swampy areas appears to connect some of the seas on Saturn's moon Titan, as seen in this comparison of data of the same area from two instruments on NASA's Cassini spacecraft. Images from the radar instrument are on the left and images from the visual and infrared mapping spectrometer (VIMS) are on the right. Credit: NASA/JPL-Caltech/University of Arizona
Are there waves on Titan’s lakes and seas? Cassini scientists say that the best chance of answering this question is with the May 23 flyby of Titan, when the Cassini spacecraft will be just 970 km (603 miles) over Titan’s biggest ‘lake,’ the northern sea named Ligeia Mare.
Lakes, seas, and rivers were discovered on Titan by Cassini in 2005, and since then, scientists and space enthusiasts have been intrigued about the possibility of what could be found in these bodies of hydrocarbon liquid. Future potential missions such as paddleboats have even been proposed.
Lakes, seas and rivers of liquid hydrocarbons cover much of the Titan’s northern hemisphere. Additionally, these hydrocarbons may rain down on the surface. The questions is, are these frigid liquid bodies capable of producing wave action, or would they be a rigid type of frigid? With surface temperature at -178 degrees Celsius (-289 degrees Fahrenheit), Titan’s environment is too cold for life as we may know it, but its environment, rich in the building blocks of life, is of great interest to astrobiologists.
Additionally, new models of Titan’s atmosphere prediction that as the seasons change in Titan’s northern hemisphere, waves could ripple across the moon’s hydrocarbon seas, and possibly even hurricanes could begin to swirl over these areas, too. The model predicting waves tries to explain data from the moon obtained so far by Cassini.
“If you think being a weather forecaster on Earth is difficult, it can be even more challenging at Titan,” said Scott Edgington, Cassini’s deputy project scientist at NASA’s Jet Propulsion Laboratory, Pasadena, Calif. “We know there are weather processes similar to Earth’s at work on this strange world, but differences arise due to the presence of unfamiliar liquids like methane. We can’t wait for Cassini to tell us whether our forecasts are right as it continues its tour through Titan spring into the start of northern summer.”
For the flyby on May 23, the altimetry data that will be collected by the radar instrument could show whether the surface of that sea is thick like molasses or as thin as liquid water on Earth.
In addition, radar will look for changes in small northern lakes last observed in previous flybys, the T-16 and T-19 flybys.
This flyby is a carefully planned sibling of the following flyby; the combination of the data from T-91 and T-92 will provide stereo views of the same geography, which will tell us about the depth of the lake walls.
Saturn seen by the Cassini spacecraft in late 2012. If you look carefully, you can spot the shadow of Mimas in the image. Credit: NASA/JPL-Caltech/Space Science Institute
The mystery of Saturn’s bright, youthful appearance is a step closer to resolution. And it actually has to do with gas.
Layers of gas within the ringed giant trap heat emanating from the center, preventing the planet from cooling off as it was expected to do as it aged, according to a model developed by a European science team.
“Scientists have been wondering for years if Saturn was using an additional source of energy to look so bright, but instead our calculations show that Saturn appears young because it can’t cool down,” stated Gilles Chabrier, a physics and astronomy professor at the University of Exeter and part of the research team.
“Instead of heat being transported throughout the planet by large scale (convective) motions, as previously thought, it must be partly transferred by diffusion across different layers of gas inside Saturn. These separate layers effectively insulate the planet and prevent heat from radiating out efficiently. This keeps Saturn warm and bright.”
A raw image of Saturn taken May 4, 2013, as seen through the eyes of the Cassini probe. Credit: NASA/JPL/Space Science Institute
You can also see layered convection on Earth, pointed out scientists. In this instances, salty water stays underneath colder and less salty liquid. The salt trap stops water from moving between the layers, also stopping heat from transferring.
The findings were published in Nature Geoscience and included participation from the University of Exeter in England and the Ecole Normale Supérieure de Lyon in France.
Image of Saturn’s aurora seen at ultraviolet wavelengths. The spiral shape seen here is similar to the distorted radio aurora visualised by the team and also indicates enhanced auroral activity. Credit: ESA/NASA/Hubble
He’s not even finished his first university degree yet, but Tim Kennelly is already part of a team that is altering our perception of time on Saturn.
The University of Iowa undergrad — in junior year, yet — led a paper describing activity in Saturn’s magnetosphere, where charged particles collect and sometimes form auroras. The process changes with the Saturnian seasons and could, the university stated, help scientists better understand how long a Saturn day lasts.
The researchers used information from NASA’s Cassini spacecraft, which has been orbiting the planet and its moons since 2004. The research challenge: Saturn is a gas giant full of layers that each have their own rotational speed. That makes it hard to figure out how long Saturn’s day is. (It’s about 10 hours, but varies by latitude.)
Kennelly made direct observations of seasonal changes in a phenomenon known as Saturn kilometric radiation (SKR). This robust radio signal was first discovered several decades ago and is being examined more closely by Cassini.
“UI space physicist Donald Gurnett and other scientists showed that the north and south poles have their own SKR ‘days’ that vary over periods of weeks and years,” the university stated. “How these different periods arise and are driven through the magnetosphere has become a central question of the Cassini mission, according to NASA officials.”
Kennelly observed, from looking at data collected between 2004 and 2011, that SKAs are linked with “flux tubes” that are made up of plasma, or superhot gas. These tubes happen around the same time of instances of SKAs in the northern and southern hemisphere, which changes seasonally.
It’s possible that this understanding could be carried over to other planets, the university stated, including our own.
“This finding may alter how scientists look at the Earth’s magnetosphere and the Van Allen radiation belts that affect a variety of activities at Earth ranging from space flight safety to satellite and cell phone communications,” it added.
This won’t be Kennelly’s only degree. He is about to apply to graduate schools, and he has aims to earn a doctorate in plasma physics.
“I’m pleased to have contributed to our understanding of Saturn’s magnetosphere so early in my career,” stated Kennelly. “I hope this trend continues.”
The research is described in the American Geophysical Union’s Journal of Geophysical Research.
