NASA is inviting the public to look skyward and wave at Saturn and Mercury in what is billed as an interplanetary photo op.
The Cassini spacecraft in orbit around Saturn and the Messenger craft circling Mercury moved into position Friday to take pictures of Earth, which will appear as a dot.
At the time of Friday's Cassini photo shoot, North America will be in sunlight. Europe, the Middle East and Central Asia will be illuminated in portraits by Messenger on Friday and Saturday.
Scientists say the snapshots of Earth are part of a bigger effort to study Saturn's shimmering rings and search for moons around Mercury.
It'll take days to weeks to process the images.
Color and black-and-white images of Earth taken by two NASA interplanetary spacecraft on July 19 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.
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 interplanetary distances. 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.
Image: This July 19, 2013 image from the Cassini spacecraft provided NASA shows the planet Earth, bright dot at center right, below Saturn's rings. The image is only one footprint in a mosaic of 33 footprints covering the entire Saturn ring system, including Saturn itself. At each footprint, images were taken in different spectral filters for a total of 323 images: some were taken for scientific purposes and some to produce a natural color mosaic. This is the only wide-angle footprint that has the Earth-moon system in it.