The imaging teams for NASA's missions to Saturn and Mercury are showing off new views of Earth and the moon, seen as mere points of light against the blackness of space.
The pictures from the Cassini orbiter at Saturn, and the Messsenger orbiter at Mercury, update the humbling message delivered by the late astronomer Carl Sagan about our "pale blue dot": Virtually all of humanity's tragedies and triumphs have played out in just a couple of pixels on the cosmic screen.
Cassini acquired its imagery from a vantage point behind a backlit Saturn on Friday, while Messenger captured its views on Friday and Saturday during a project to look for small satellites of Mercury. The raw imagery from Saturn surfaced over the weekend and inspired a wave of unofficial planetary portraits, but it took until Monday for the science teams for Cassini and Messenger to release the official versions.
Carolyn Porco, an astronomer at the Space Science Institute who heads Cassini's imaging team, organized a consciousness-raising campaign called "The Day the Earth Smiled" in conjunction with Friday's photo op. NASA mounted a social-media effort called "Wave at Saturn." On Monday, both NASA and the Space Science Institute hailed the interplanetary picture-taking session as a huge success.
"We can't see individual continents or people in this portrait of Earth, but this pale blue dot is a succinct summary of who we were on July 19," the Cassini mission's project scientist, Linda Spilker of NASA's Jet Propulsion Laboratory, said in a news release. "Cassini's picture reminds us how tiny our home planet is in the vastness of space, and also testifies to the ingenuity of the citizens of this tiny planet to send a robotic spacecraft so far away from home to study Saturn and take a look-back photo of Earth."
Porco praised the salutes to Saturn from our own planet.
"It thrills me to no end that people all over the world took a break from their normal activities to go outside and celebrate the interplanetary salute between robot and maker that these images represent," she said. "The whole event underscores for me our 'coming of age' as planetary explorers."
Cassini captured 323 images documenting a wide-angle view of Saturn and its moons, with Earth and our own moon off to one side. The bus-sized spacecraft was 753,000 miles (1.2 million kilometers) behind Saturn and 898.4 million miles (1.45 billion kilometers) from Earth at the time. Although the part of the picture showing Earth and the moon was released Monday, it will take weeks more for the full-color mosaic of the entire scene to be assembled.
Messenger's black-and-white pictures were taken from a vantage point 61 million miles (98 million kilometers) away from Earth. Mercury itself doesn't appear in the imagery, because the glare from the planet would have washed out the specks of light representing our cosmic locale. The size of those specks in a typical Messenger image would be less than a pixel wide, but they appear artificially large here because of overexposure.
"That images of our planet have been acquired on a single day from two distant solar system outposts reminds us of this nation's stunning technical accomplishments in planetary exploration," Sean Solomon, an astronomer at Columbia University's Lamont-Doherty Earth Observatory who serves as the Messenger mission's principal investigator, said in Monday's news release. "And because Mercury and Saturn are such different outcomes of planetary formation and evolution, these two images also highlight what is special about Earth. There's no place like home."
Update for 9:15 p.m. ET July 22: This view of Earth and the moon seems to have hit a chord on Twitter. It's Earth's pale blue dot as seen in Cassini's wide-angle view, blown up so much that the individual pixels become pale blue squares. The moon is the dim pixel on the right.
More about planetary views:
- Did you smile for the deep-space camera?
- Venus sparkles in views from Saturn
- NBC News archives on Saturn | Mercury
Alan Boyle is NBCNews.com's science editor. Connect with the Cosmic Log community by "liking" the NBC News Science Facebook page, following @b0yle on Twitter and adding +Alan Boyle to your Google+ presence. To keep up with NBCNews.com's stories about science and space, sign up for the Tech & Science newsletter, delivered to your email in-box every weekday. You can also check out "The Case for Pluto," my book about the controversial dwarf planet and the search for new worlds.