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Revised "Pale Blue Dot" Photo

posted May 15, 2011, 8:04 PM by Abel Mendez Torres   [ updated Jul 28, 2012, 1:22 PM ]
On 1990 Voyager 1 took a photo of Earth from a distance of 40.5 astronomical units (AU), at the edge of the Solar System. This famous photo named the "Pale Blue Dot" by Carl Sagan is currently the farthest photo taken of Earth. At that distance, and with the limitations of the Voyager I Narrow Angle Camera, Earth looks like a simple pale blue dot in the blackness of the space (Figure 1). Here we corrected the image by subtracting the solar reflection background of the original image (Figure 2) and enhancing and fixing the colors to the characteristics Earth's blue-white tones. Earth itself should take less than one pixel (0.12 pixels) in the image but optical effects and the exposure time makes it take a few pixels.

The Moon is not visible but is very close to Earth and probably contributed to the pixels information. A reconstruction of the scene using NASA Solar System Simulator shows the relative distance between Earth and the Moon at the moment of the photo (Feb. 14, 1990) and at the same resolution of 0.00053°/pixel (Figure 3). A zoom of the frame shows the Earth crescent shape (Figure 4). However, the "Pale Blue Dot" photo was taken sometime between Feb. 14 and Jun. 6, 1990 and the exact position of the Moon at the moment of the image might not be correct. Also note that Earth and Moon appears larger in these NASA Solar System Simulator renderings.


Figure 1. Revised "Pale Blue Dot" photo with text (Sun was in the upper right out of the frame). Adding the text and recompression modified a little the original pixels, but here is without text.


Figure 2. Original "Pale Blue Dot" photo (Sun was in the upper right out of the frame).


Figure 3. Context image of Earth and the Moon at the time of the "Pale Blue Dot" photo and with the same resolution [614x453] (Sun was in the lower right out of the frame).


Figure 4. Enlarged context image of Earth at the time of the "Pale Blue Dot" photo (Sun was in the lower right out of the frame).