Color and black-and-white images of Earth have been delivered by two NASA interplanetary spacecraft
on July 19. The images show our planet and its moon as bright beacons from millions of miles away in space.
NASA's Cassini spacecraft captured the color images of Earth and the moon from its perch in the Saturn system nearly
900 million miles (1.5 billion kilometers) away.
MESSENGER, the first probe to orbit Mercury, took a black-and-white image from a distance of 61 million miles
(98 million kilometers) as part of a campaign to search for natural satellites of the planet.
Click on image to enlarge
In this rare image taken on July 19, 2013, the wide-angle camera on NASA's Cassini
spacecraft has captured Saturn's rings and our planet Earth and its moon in the same frame. Image Credit:
NASA/JPL-Caltech/Space Science Institute
In the Cassini images Earth and the moon appear as mere dots -- Earth a pale blue and the moon a stark white, visible
between Saturn's rings. It was the first time Cassini's highest-resolution camera captured Earth and its moon as
two distinct objects.
It also marked the first time people on Earth had advance notice their planet's portrait was being taken from
NASA invited the public to celebrate by finding Saturn in their part of the sky, waving
at the ringed planet and sharing pictures over the Internet. More than 20,000 people around the world participated.
"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
"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.
Click on image to enlarge
These images show views of Earth and the moon from NASA's Cassini (left) and MESSENGER spacecraft (right) from July 19, 2013.
Image Credit: NASA/JPL-Caltech/Space Science Institute and NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington
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.
The cameras on NASA's Cassini spacecraft captured this rare look at Earth
and its moon from Saturn orbit on July 19, 2013. Image Credit: NASA/JPL-Caltech/Space Science Institute
"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," said Carolyn Porco,
Cassini imaging team lead at the Space Science Institute in Boulder, Colo.
"The whole event underscores for me our 'coming of age' as planetary explorers."
In the MESSENGER image, Earth and the moon are less than a pixel, but appear very large because they are overexposed.
Long exposures are required to capture as much light as possible from potentially dim objects. Consequently, bright
objects in the field of view become saturated and appear artificially large.
"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," said MESSENGER Principal Investigator
Sean Solomon of Columbia University's Lamont-Doherty Earth Observatory in Palisades, N.Y.
"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."