“There’s no place like home…”

I didn’t ‘Wave at Saturn’ on 19 July when the Cassini probe, orbiting the gas giant, was taking a high-definition image of the view back home.  I don’t think it encouraged a proper sense of perspective…  But the resultant image is stunning. [Image Credit: NASA/JPL-Caltech/Space Science Institute]

Cassini image of Earth in Saturn's rings

It’s not the first time Cassini has looked home.  Nor is it the only stunning image the probe has provided.  But, as those involved pointed out

“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,” said Linda Spilker, Cassini project scientist, at NASA’s Jet Propulsion Laboratory in Pasadena, Calif. “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.”

Pictures of Earth from the outer solar system are rare because from that distance, Earth appears very close to our sun. A camera’s sensitive detectors can be damaged by looking directly at the sun, just as a human being can damage his or her retina by doing the same. Cassini was able to take this image because the sun had temporarily moved behind Saturn from the spacecraft’s point of view and most of the light was blocked.

A wide-angle image of Earth will become part of a multi-image picture, or mosaic, of Saturn’s rings, which scientists are assembling. This image is not expected to be available for several weeks because of the time-consuming challenges involved in blending images taken in changing geometry and at vastly different light levels, with faint and extraordinarily bright targets side by side.

Here’s the image again, with the Earth helpfully identified.

Annotated Cassini image of Earth in Saturn's rings

And the same image magnified five times to show the Earth and Moon.

Magnified Cassini image of Earth and Moon

Not to be outdone Messenger, still in orbit around Mercury, also took a look home. [Image credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington]

Montage Earth Moon by Messenger

Of course, the original ‘Pale Blue Dot’, as imaged by the Voyager 1  probe in 1990, remains iconic.

And, because I can, here’s Messenger’s last wondrous look home. [NASA’s Messenger probe to Mercury flies past Earth, August 2, 2005. (Image credits: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington)]