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Pluto and its biggest moon grow larger in NASA probe's windshield

Image: Pluto and Charon
The picture at left shows Pluto and Charon as seen by New Horizons' Long Range Reconnaissance Imager. The brighter spot is Pluto. Circles have been added to the image at right to highlight the spots.

Pluto and its biggest moon, Charon, stand out as separate spots in the sky in the first such pictures taken by the high-resolution camera on NASA's New Horizons probe.

The images were taken on July 1 and 3 by New Horizons' Long Range Reconnaissance Imager, or LORRI, when the spacecraft was 550 million miles (885 million kilometers) away. Six pictures were combined into a composite view that shows the dwarf planet Pluto as a bright spot, and Charon as a dimmer spot at about the 11 o'clock position relative to Pluto.

These pictures serve as a warmup for New Horizons' Pluto flyby on July 14, 2015.

"The image itself might not look very impressive to the untrained eye, but compared to the discovery images of Charon from Earth, these ‘discovery’ images from New Horizons look great!” the project scientist for New Horizons, Hal Weaver of Johns Hopkins University Applied Physics Laboratory, said Wednesday in a news release. “We’re very excited to see Pluto and Charon as separate objects for the first time from New Horizons.”

New Horizons' principal investigator, Alan Stern of the Southwest Research Institute, said the images could yield new information about the surface properties of Pluto and Charon — for example, the existence of an overlying layer of fine particles. Researchers have speculated that nitrogen and methane may freeze out of Pluto's thin atmosphere and fall like "snow" as the world retreats from the closest point in its orbit around the sun.

"We're excited to have our first pixel on Charon," Stern said, "but two years from now, near closest approach, we'll have almost a million pixels on Charon — and I expect we'll be about a million times happer, too!"

Stern told NBC News that the apparent size of the objects will be twice as big next year, and four times as big in 18 months. But LORRI's resolution won't start beating the best that the Hubble Space Telescope can do until early 2015.

The $700 million New Horizons mission was launched in 2006, before the International Astronomical Union reclassified Pluto as a dwarf planet. For much of the time since then, the piano-sized spacecraft has been in hibernation, with periodic wake-up calls for system checks and picture-taking sessions. The science team's members haven't been hibernating, however: Later this month, they're due to gather at the Applied Physics Laboratory in Maryland for a conference looking ahead to 2015's encounter with Pluto.

Stay tuned for lots more about Pluto over the next two years: It may be a dwarf — but as any fan of "Game of Thrones" knows, dwarves can be a big, big deal.

More about Pluto and its moons:

Alan Boyle is NBCNews.com's science editor. Connect with the Cosmic Log community by "liking" the NBC News Science Facebook page, following@b0yle on Twitter and adding +Alan Boyle to your Google+ circles. To keep up with NBCNews.com's stories about science and space, sign up for the Tech & Science newsletter, delivered to your email in-box every weekday. You can also check out "The Case for Pluto," my book about the controversial dwarf planet and the search for new worlds.