Night on Saturn

About a month and a half ago (11 Oct 2006), NASA released this absolutely stunning image of the night side of Saturn, taken from a composite of 165 Cassini photographs:

Night on Saturn
Source: NASA

NASA explains how the image was obtained:

With giant Saturn hanging in the blackness and sheltering Cassini from the sun’s blinding glare, the spacecraft viewed the rings as never before, revealing previously unknown faint rings and even glimpsing its home world.

This marvelous panoramic view was created by combining a total of 165 images taken by the Cassini wide-angle camera over nearly three hours on Sept. 15, 2006. The full mosaic consists of three rows of nine wide-angle camera footprints; only a portion of the full mosaic is shown here. Color in the view was created by digitally compositing ultraviolet, infrared and clear filter images and was then adjusted to resemble natural color.

(continue reading at NASA’s web site)

A very-high resolution image (2766×1364) is available, quite suitable for the background image on computer desktops (it’s what mine is set to). Or, if you prefer, a very-high resolution image with the color contrast enhanced is also available. This is a view not visible from Earth: since Saturn orbits the sun at such a large distance (its orbit is almost sixty times as wide as Earth’s), its day side always faces us. Only a small crescent of its night side can ever be seen from Earth-based cameras.

While the image itself is breathtaking, there is an added gem. As the NASA description continues (emphasis mine)

Interior to the G ring and above the brighter main rings is the pale dot of Earth. Cassini views its point of origin from over a billion kilometers (and close to a billion miles) away in the icy depths of the outer solar system.

The small point that is Earth can only be seen on the very-high resolution image. Again, since Saturn orbits the sun much farther away than the Earth does, from Saturn’s perspective, Earth will always seem to be close to the sun. With Saturn blocking the sun, Cassini was able to capture Earth in the picture as well.

This brings to mind another remarkable photograph. On 6 June 1990, at the suggestion of astronomer (and popular science writer) Carl Sagan, Voyager 1’s cameras were aimed back home. At a distance of over 6 billion kilometers (4 billion miles), past the orbit of Pluto, it sent back this humbling image.

Pale Blue Dot
Source: NASA

The three rays are artifacts, a result of taking a picture so close to the sun. If you look closely, around the center of the ray on the right, you will see a tiny dot. That’s Earth (its position in the ray is coincidental). At this range, Earth is about the size of one-eighth of a pixel. The photograph has been entitled “Pale Blue Dot” and served as an inspiration for a book Mr. Sagan wrote, called Pale Blue Dot: A Vision of the Human Future in Space, a book which unfortunately is still on my list of books to read. He describes the photograph in supremely eloquent fashion:

We succeeded in taking that picture [from deep space], and if you look at it, you see a 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 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.

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5 thoughts on “Night on Saturn

  1. My wife and I enjoyed the recent issue of National Geographic, which has a stunning article about the Cassini fly-by of Saturn. Of course, the photos are amazing.

  2. → Peneroso Really? I’ll have to take a look at it. Sky & Telescope just published their yearly “Beautiful Universe” issue, featuring a large collection of all sorts of remarkable astronomy images from the past year, including the one of Saturn. In fact, that’s one of the factors that prompted this post.

    → Ncurse I’m glad you like them; they are unbelievable. But no, no bravery is needed. The works of NASA, as part of the U.S. federal government, are in general in the public domain (see these guidelines, for example). As for Mr. Sagan’s description, it is rather well-known. Those three paragraphs have been extensively quoted; for instance, see Wikipedia’s page on “Pale Blue Dot” or a Google search.

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