Composite image of Saturm from HST (Credit NASA/ESA)
I can remember it very well, although not actually sure when it was, back around 1995/1996 I think. I was, like most other keen stargazers very familiar with the sight of Saturn with rings and all. Indeed the view of Saturn with its rings was one of the first things I had ever seen through a telescope and it inspired me into a lifetime passion of exploring the night sky. Every 15 years though, the Earth passes through the plane of the rings and from Earth they seem to vanish. Now, an astronomer has used data taken during such ring plane crossings from the Cassini spacecraft to measure the transparency of the rings.
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.
