This photo mosaic combines photos from Voyager 1's 1979 Jupiter flyby to provide our best view ever of the Great Red Spot, the gigantic storm that has raged on that planet for centuries and is twice as big as Earth.
This amazing image is the work of Icelandic amateur image processor Björn Jónsson, who combed through all the many photos taken during the Voyager flyby in order to make this mosaic view of the Great Red Spot. These photos have been publicly available for three decades, but only now has someone bothered to find them and put them together like this. Jónsson also took the liberty of greatly increasing the contrast of the image, providing a much clearer view of the spot.
The Great Red Spot is a massive storm system that has been in existence for anywhere from 180 to 345 years, and it's currently about 24,000 to 40,000 kilometers long from east to west, and 12,000 to 14,000 kilometers north to south. The spot slowly rotates counterclockwise at a rate of about once very six Earth days. It's not currently known how long the spot will last, but it is getting smaller. Scientists estimate it's only about half the size now that it was a century ago.
You can click on the image up top for a much closer look at this amazing image. For more on how the mosaic was put together, check out this post at the Planetary Society Blog.