NASA’s MESSENGER spacecraft has captured the first portrait of our Solar System from the inside looking out.
Comprised of 34 images, the mosaic provides a complement to the Solar System portrait—that one from the outside looking in—taken by Voyager 1 in 1990 (see below).
“Obtaining this portrait was a terrific feat by the MESSENGER team,” says MESSENGER Principal Investigator Sean Solomon, of the Carnegie Institution of Washington.
“This snapshot of our neighbourhood also reminds us that Earth is a member of a planetary family that was formed by common processes four and a half billion years ago,” he added.
“Our spacecraft is soon to orbit the innermost member of the family, one that holds many new answers to how Earth-like planets are assembled and evolve.”
MESSENGER’s Wide Angle Camera (WAC) captured the images on November 3 and 16, 2010. In the mosaic, all of the planets are visible except for Uranus and Neptune, which—at distances of 3.0 and 4.4 billion kilometres—were too faint to detect.
Earth’s Moon and Jupiter’s Galilean satellites (Callisto, Ganymede, Europa, and Io) can be seen in the NAC image insets. The Solar System’s perch on a spiral arm of the Milky Way galaxy also afforded a beautiful view of a portion of the galaxy in the bottom centre.
Assembling this portrait was no easy feat, says Solomon. “It’s not easy to find a moment when many of the planets are within a single field of view from that perspective, and we have strong Sun-pointing constraints on our ability to image in some directions.”
Outside looking in
On February 14, 1990, NASA’s Voyager 1 spacecraft had sailed beyond the outermost planet in our Solar System and turned its camera inward to snap a series of final images that would be its parting valentine to the string of planets it called home.
Mercury was too close to the Sun to see, Mars showed only a thin crescent of sunlight, and Pluto was too dim, but Voyager was able to capture cameos of Neptune, Uranus, Saturn, Jupiter, Earth and Venus from its unique vantage point. These images, later arranged in a large-scale mosaic, make up the first family portrait of our planets arrayed about the Sun.
Candy Hansen, a planetary scientist based at NASA’s Jet Propulsion Laboratory, who worked with the Voyager imaging team at the time, remembers combing through the images and finally finding the image of Earth. She had seen so many pictures over the years that she could distinguish dust on the lens from the black dots imprinted on the lens for geometric correction.
There was our planet, a bright speck sitting in a kind of spotlight of sunlight scattered by the camera. Hansen still gets chills thinking about it.
“I was struck by how special Earth was, as I saw it shining in a ray of sunlight,” she said. “It also made me think about how vulnerable our tiny planet is.”
This was the image that inspired Carl Sagan, the Voyager imaging team member who had suggested taking this portrait, to call our home planet “a pale blue dot.”
As he wrote in a book by that name, “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. … There is perhaps no better demonstration of the folly of human conceits than this distant image of our tiny world.”
MESSENGER (MErcury Surface, Space ENvironment, GEochemistry, and Ranging) is a NASA-sponsored scientific investigation of the planet Mercury and the first space mission designed to orbit the planet closest to the Sun.
MESSENGER was launched on August 3, 2004, and—having completed flybys of Earth, Venus, and Mercury—will start a yearlong study of its target planet in March 2011.
Adapted from information issued by NASA / JPL-Caltech. Image credits: (MESSENGER) NASA / JHU APL / Carnegie; (Voyager) NASA / JPL.
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