Say “cheese” and give Saturn a wave on Friday July 19

Cassini photo mosaic of Saturn, backlit by the sun, back in September 2006. Earth is between tick marks at left. Click to supersize. Credit: NASA/ JPL-Caltech

I’m a sucker for corny cosmic ideas. On Friday afternoon July 19, cameras on the Cassini spacecraft will take a series of photos of our home planet from nearly one billion miles away. NASA suggest we all wave. Count me in.

The probe, which has been circling Saturn since 2004, will take a series of photos of our home planet from nearly one billion miles away over a 15-minute span beginning at 4:27 p.m. (Central Daylight Time) and ending at 4:42 p.m. The “flashbulb” for the event will be none other than the sun. Say “cheese”!

This simulated view from NASA’s Cassini spacecraft shows the expected positions of Saturn and Earth on July 19, 2013, around the time Cassini will take Earth’s picture. Cassini will be about 898 million miles (1.44 billion km) away from Earth at the time.  Credit: NASA/JPL-Caltech

Seen from so far away Earth will be no more than 1.5 pixels wide, but squished into that dot will be all of us and every other living thing. Of course half of humanity will be facing away from the camera, but if you live in North America, the western parts of Europe and Africa or happen to be crossing the Atlantic in a plane at the time, you can smile right at the photographer. The eastern hemisphere will have its back to the camera.

Since the U.S. and Canada will be in sunlight when the photo’s taken, you’ll have to picture Saturn in your mind’s eye. This map shows the Chicago skyline at 4:27 p.m. when the portrait session begins. Saturn will be a little more than two outstretched fist high (25 degrees) in the southeastern sky. Credit: NASA/ JPL

Waving’s an even better idea because it feels more like participation. Go for it, I say. When taking a portrait, it’s always a good idea to face the photographer, so to help you know where to look, the folks at NASA have prepared a series of maps for locating Saturn.

From Los Angeles, Calif. Saturn will be nearly due east at 2:27 p.m. and slightly less than one fist (8 degrees) above the horizon. Credit: NASA/JPL

Earth will appear as a pale blue dot in Cassini’s cameras to the lower right of the Saturn’s ring plane. While the historic portrait is being taken, mission planners will also have science on their minds. They hope that the probe’s unique vantage point directly behind the planet in its shadow will provide an ideal opportunity to to study fine particles and structures within the rings.

Saturn will be easily visible low in the southwestern sky at 11:27 p.m. London (Greenwich) time on July 19. Click to see maps for other locales. Credit: NASA/ JPL

“Looking back towards the sun through the rings highlights the tiniest of ring particles, whose width is comparable to the thickness of hair and which are difficult to see from ground-based telescopes,” said Matt Hedman, a Cassini science team member based at Cornell University in Ithaca, N.Y. Hedman and others also have their eye on Saturn’s E-ring, a diffuse ring fashioned from salty bits of ice blasted by geysers on the moon Enceladus.

Detail of the September 2006 picture of Saturn and Earth (tiny dot at upper right). A further enlargement at left shows the moon as a smaller, fuzzy spot next to Earth. The July 19 photo will also show both moon and Earth. Credit: NASA/ JPL-Caltech

Cassini’s taken Earth’s picture before – in 2006 and 2012 – but this time will use its highest resolution camera and shoot the scene in natural color just the way we’d see it if we could cruise alongside the spacecraft.

Our species is equally adept at doing good and bad. The Cassini portrait is one of those good things we can be proud of. Working together we built a machine that not only explores new worlds but casts a brand new light on the old one.

Simulation of the Earth and moon seen from Saturn on July 19. Because the two planets are so far from one another, the moon will appear much closer to Earth than shown here. Credit: Tom Ruen

“I wanted to turn the entire event into an opportunity for everyone around the globe to savor the uniqueness of our planet and the preciousness of the life on it,” says Carolyn Porco, Cassini imaging team leader.

Now isn’t that worth smiling about?

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