OK, everybody, say hi to saturn

NASA's Cassini spacecraft has taken pictures of Saturn and Earth before. In this 2006 image, Earth is a tiny dot on the left, just to the inside of the second outer ring.

As far as we know, there are no Saturnians on Saturn. There are no sirens on Titan nor large, monolithic stargates floating just outside Iapetus.

And even if there were, they couldn't see us. Not in much detail, anyway. We're more than a billion kilometers away.

But we're going to wave and smile at them anyway. At least, that's the plan hatched by NASA and "The Day the Earth Smiled," organized by Cassini Imaging Team Leader Carolyn Porco.

On Friday, the Cassini-Huygens spacecraft -- serving humanity since 1997 and in orbit around the ringed giant since 2004 -- will take pictures of Saturn and its rings during a solar eclipse. Included in the images, though just the barest dot, will be our Big Blue Marble.

Porco has high hopes for the extraterrestrial picture-taking, which will occur from 21:27 to 21:42 UTC. (That's 5:27 p.m. to 5:42 p.m. Eastern Daylight Time in the United States, subtracting an hour for each time zone to the west.)

"I hope, at the appropriate time, that you stop what you're doing, go outside, gather together with friends and family ... and marvel at your own existence and that of all life on planet Earth," she writes on her website. "Then, by all means, rejoice!"

NASA has a catchier name for the image shoot. The agency is calling it "The First Interplanetary Photobomb." The Jet Propulsion Laboratory is asking viewers to "wave at Saturn."

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Is there an astronomical point to such celebrating?

Well, NASA points out, it's not like Earth is often photographed from the far reaches of outer space. "Opportunities to image Earth from the outer solar system are rare," the agency says in its "Photobomb" press release. "Since the Space Age began, there have been only two images of Earth from the outer solar system."

The space agency is going to snap images from the other side of the solar system as well. NASA's MESSENGER spacecraft is in orbit around Mercury, and staffers "realized Earth is coincidentally expected to appear in some images taken in a search for natural satellites around Mercury on July 19 and 20," NASA and JPL said in a press release.

So MESSENGER will take photos at 7:49 a.m., 8:38 a.m. and 9:41 a.m. EDT (11:49, 12:38 and 13:41 UTC) on both days, NASA and JPL said. (Yeah, the Friday opportunity is gone, but you still have Saturday for the salute to Mercury.)

The release said that NASA was inspired, in part, by the Cassini team.

And maybe the ultimate point of all this should be more existential, anyway. On Saturday, we'll celebrate the 44th anniversary of the Apollo 11 moon landing. Neil Armstrong and Buzz Aldrin's stroll on the moon's surface is still considered one of the most amazing achievements in human history. As The Onion famously once said in a headline, "Holy S***, Man Walks on F****** Moon."

We haven't been back to the moon since 1972, but the steady stream of space images from NASA and others still has the ability to make us contemplate the sheer wonder of it all.

So, what can it hurt? Take a few minutes and smile and wave for Earth. You never know who might be watching.