NASA’s Cassini spacecraft—in orbit around Saturn—took a picture of Earth last Friday, July 19, from nearly 900 million miles away. The entire image, which will take several weeks to develop, will depict more than just our planet (a “ pale blue dot ,” a fraction of a pixel, compared to everything else). For now, we have a portion of it. It took approximately 1 hour, 20 minutes and 24 seconds for the photons that went into this image to reach Cassini’ s wide-angle lens.
Here’s Lee Billings, writing for Scientific American before the photo shoot:
Built, launched and operated at a total cost of more than $3 billion, Cassini will spend 15 minutes capturing a natural-color photographic mosaic of Saturn’s “E” ring, an annulus of dust and water ice fed by plumes of vapor venting from somewhere warm, wet, and potentially habitable deep within the icy moonEnceladus . Another attraction will lurk in the far distance, barely visible just outside the E ring by virtue of Saturn’s deep shadow: The blue crescent of the sunlit Earth, bearing an untold number of upturned gazes from potential fans in the continental United States, the Caribbean, Central America, or the eastern half of the South Pacific. With a bit of luck, Cassini might also glimpse Earth’s adjacent Moon.
Carolyn Porco, leader of Cassini ’s imaging team, says this is likely the last time the satellite will observe the Earth. In 2017, the craft will reach the end of its life and will descend into Saturn’s atmosphere; until then, researchers are hoping to make the most of its flight.
“It’s not clear when we’ll ever do this again,” Porco says. “Missions this big and ambitious aren’t really in vogue anymore, so maybe we’ll only have a spacecraft this sophisticated out there once every hundred years. I do see this as probably our last great, gorgeous look back at Saturn and at the Earth before Cassini goes dark.”
Space enthusiasts across the globe waved at Saturn on Friday. Take a look at NASA’s collection of photos from people who joined in.