Today's Image of the Day on presents us a nice big version of the first spaceborn portrait of Saturn. The image above was taken by the Pioneer 11 spacecraft launched from Cape Canaveral forty years ago, on April 5, 1973.

Pioneer 11's path through Saturn's outer rings took it within 21,000 km of the planet, where it discovered two new moons (almost smacking into one of them in September 1979) and a new "F" ring. The spacecraft also discovered and charted the magnetosphere, magnetic field and mapped the general structure of Saturn's interior. The spacecraft's instruments measured the heat radiation from Saturn's interior and found that its planet-sized moon, Titan, was too cold to support life. This image from Pioneer 11 shows Saturn and its moon Titan. The irregularities in ring silhouette and shadow are due to technical anomalies in the preliminary data later corrected. At the time this image was taken, Pioneer was 2,846,000 km (1,768,422 miles) from Saturn.

As Hamish Lindsay remembers:

Although very poor quality by Voyager and Cassini standards, when this picture came out in 1979 we were all very excited as it was the first time we had an image of Saturn that exceeded the best Earth-based telescope pictures.

Well, NASA, thank you for the huge version: