Friday, July 12, 2013

NASA SPOTS PLUTO'S LARGEST MOON CHARON.

NEW DELHI: In what is being called the inauguration of an exciting new era of exploration, Nasa's New Horizons spacecraft has taken its first photograph of Pluto's icy moon Charon from 880 million miles away.

Launched on 19 January 2006 and estimated to reach the dwarf planet Pluto in 2015, the robotic spacecraft snapped six photographs of Charon using its highest-resolution telescopic camera. New Horizons will be the first spacecraft to explore Pluto, its five moons, and the weird Kuiper Belt of which they are residents.

The largest of Pluto's five known moons, Charon orbits more than 19,000 kilometers away from Pluto itself. As seen from New Horizons, that's only about 0.01 degree away.

"We're excited to have our first pixel on Charon," says New Horizons Principal Investigator Alan Stern, "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 happier too!"

The spacecraft was still 880 million kilkometers from Pluto-farther than the distance from Earth to Jupiter-when its LOng Range Reconnaissance Imager (LORRI) snapped the images: three on July 1 and three more on July 3. LORRI's excellent sensitivity and spatial resolution revealed Charon at exactly the predicted offset from Pluto, 35 years after the announcement of Charon's discovery in 1978 by James Christy of the Naval Observatory.

"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!" says New Horizons Project Scientist Hal Weaver, of the Johns Hopkins University Applied Physics Laboratory. "We're very excited to see Pluto and Charon as separate objects for the first time from New Horizons."

"In addition to being a nice technical achievement, these new LORRI images of Charon and Pluto should provide some interesting science too," Stern says.

New Horizons is viewing Pluto and Charon at solar phase angles (the angles between the Sun, Pluto and spacecraft) much larger than can be achieved from observatories located on or near the Earth, potentially yielding important information about the surface properties of Charon and Pluto-perhaps the existence of an overlying layer of fine particles, for example.

When New Horizons reaches Pluto on 14 July 2015, it will pass as close to the surface as 12500 kilometers above it. LORRI will be able to snap very clear pictures - the first ever - of the dwarf planet. It will also study the five moons - Charon, Nix, Hydra, Kerberos and Styx. The last two were discovered in 2011 and 2012 respectively and were formally named only last month.

Pluto used to be the ninth planet in the Solar System till 2006, when the International Astronomical Union demoted it to dwarf planet status.

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