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Ceres is the largest object in the asteroid belt, and NASA's Dawn spacecraft will arrive there on March 6. Pluto is the largest object in the Kuiper belt, and NASA's New Horizons spacecraft will arrive there on July 15... The efforts of a very small clique of Pluto-haters within the International Astronomical Union (IAU) plutoed Pluto in 2006. Of the approximately 10,000 internationally registered members of the IAU in 2006, only 237 voted in favor of the resolution redefining Pluto as a "dwarf planet" while 157 voted against; the other 9,500 members were not present... Unlike the larger planets, however,...

The dwarf planet Pluto and its system of five moons are about as mysterious as the underworld of antiquity that inspired their names. ... “We are still baffled by how the system formed,” says study co-author Mark Showalter, a senior research scientist at the Search for Extraterrestrial Intelligence (SETI) Institute. “I think everyone believes that, at some point in the distant past, a large object bashed into ‘proto-Pluto’ and the moons formed out of the debris cloud. However, after that point in the story, details get very sketchy.” Now, analysis of data collected from the Hubble Space Telescope following the...

Puto Video http://cdn.theguardian.tv/mainwebsite/2015/04/16/150416pluto_desk.mp4 Pluto’s moons have been tracked closely for the first time, showing that they tumble unpredictably rather than keeping one face fixed on their host planet. Astronomers also observed that Pluto, whose status was downgraded to a dwarf planet in 2006, might be better regarded as a binary dwarf as it is locked in orbit with its largest moon, called Charon. The twin system creates an imbalanced and shifting gravitational field, which sends the tiny outer moons spinning chaotically, the measurements from the Hubble space telescope showed. Target Pluto: fastest spaceship set for epic encounter with our remotest...

The most recent observation took place in November of 2010, when Eris was the subject of one of the most distant stellar occultations yet achieved from Earth. The teams findings were announced on October 2011, and contradicted previous findings with an estimated diameter of 2326 ± 12 km (1445 miles). Because of these differences, astronomers have been hard-pressed to maintain that Eris is more massive than Pluto. According to the latest estimates, the Solar System’s “ninth planet” has a diameter of 2368 km (1471 miles), placing it on par with Eris. Part of the difficulty in accurately assessing the planet’s...

What a difference 20 million miles makes! Images of Pluto from NASA’s New Horizons spacecraft are growing in scale as the spacecraft approaches its mysterious target. The new images, taken May 8-12 using a powerful telescopic camera and downlinked last week, reveal more detail about Pluto’s complex and high contrast surface. These images show Pluto in the latest series of New Horizons Long Range Reconnaissance Imager (LORRI) photos, taken May 8-12, 2015, compared to LORRI images taken one month earlier. In the month between these image sets, New Horizons’ distance to Pluto decreased from 68 million miles (110 million kilometers)...

Explanation: Here comes Pluto. NASA's robotic New Horizons spacecraft is now beyond the orbit of Neptune and closing fast on the Solar System's most famous unexplored world. The featured time lapse video shows Pluto and Pluto's largest moon, Charon, orbiting their common center of mass in 13 frames taken from April 12 to April 18. Although blurry, images in the video now rival even the best images of Pluto yet taken from Earth. New Horizons remains on schedule to zoom past the distant dwarf planet on July 14.

you can see the best-ever images of Pluto, our solar system's most distant (dwarf) planet. The animation is made up of images taken by NASA's New Horizons spacecraft between April 12 and 18 from a distance of 69 to 64 million miles from Pluto. They capture one complete rotation of Pluto and its moon Charon... The images have already surpassed the Hubble's resolution, but there are plenty of features too subtle for the spacecraft to pick up. In fact, the images don't even show all of Pluto's known moons yet -- let alone any smaller ones we've yet to discover...

The first spacecraft to visit distant Pluto, a dwarf planet in the solar system’s frozen backyard, is still three months away from a close encounter, but already in viewing range, newly released photos show.

On July 14, NASA’s New Horizons spacecraft will fly past Pluto, offering the first close-up look at that small, distant world and its largest moon, Charon. These denizens of the outer solar system will be transformed from poorly seen hazy bodies to tangible worlds with distinct features. Now, the public can help decide what labels will go on the images and maps coming from the flyby. The SETI Institute has announced the launch of its “Our Pluto” campaign, which is soliciting input on how to name features on the surfaces of Pluto and Charon. ... The science team will not...

It's not exactly a clean shot, but it's certainly a timely one: 85 years to the day after Pluto's discovery, NASA has released fresh images from New Horizons that show two of its smaller moons. The long-exposure images, which were taken between Jan. 27 and Feb. 8 from a distance of 125 to 115 million miles, show Hydra and Nix -- moons too small to show up in previous shots. Hydra is enclosed in a yellow diamond with Nix in orange. The image on the right has been specially processed to reduce the center glare, a result of the over-exposure...

Explanation: On another Valentine's Day 25 years ago, cruising four billion miles from the Sun, the Voyager 1 spacecraft looked back one last time to make this first ever Solar System family portrait. The complete portrait is a 60 frame mosaic made from a vantage point 32 degrees above the ecliptic plane. In it, Voyager's wide angle camera frames sweep through the inner Solar System at the left, linking up with gas giant Neptune, the Solar System's outermost planet, at the far right. Positions for Venus, Earth, Jupiter, Saturn, Uranus, and Neptune are indicated by letters, while the Sun is...

Here we go! New Horizons is now on approach and today – on the anniversary of Pluto discoverer Clyde Tombaugh’s birth – the spacecraft has sent back its first new images of the Pluto system. The images aren’t Earth-shattering (Pluto-shattering?) but they do represent the mission is closing in on its target, and will allow the New Horizons engineers to precisely aim the spacecraft as it continues its approach. The photos were taken with the telescopic Long-Range Reconnaissance Imager (LORRI) on January 25 and 27, 2015. “Pluto is finally becoming more than just a pinpoint of light,” said Hal Weaver,...

I count myself among the many astrogeeks who (1) keep track of where all the visible planets are and who (2) hold a considered opinion regarding whether Pluto should have been downgraded from full planet status. (BTW, yes, Pluto deserves the demotion to dwarf planet; not just because it is even smaller than the dwarf planet Eris, but also because Pluto can’t walk upright like Goofy). This month provides particularly interesting evenings for stargazers. Five planets — Mars, Neptune, Venus, Uranus, and Mercury — are all bunched up within a few degrees of each other from the perspective of Earth....

The mission to Pluto is being billed as the last great encounter in planetary exploration. It is one of the first opportunities to study a dwarf planet up close. The pictures are critical to enable the New Horizons probe to position itself for a closer fly-by later this year. As the probe is still 200 million km away, Pluto will be hardly discernable in the images - just a speck of light against the stars. But the mission team says this view is needed to help line up the spacecraft correctly for its fly-by on 14 July. "Optical navigation is...

While asteroids residing in the inner solar system will pass quickly through such small fields, trans-Neptunian objects (TNOs) orbit the Sun much more slowly. For example, Pluto, at an approximate distance of 40 A.U. from the Sun, along with the object Eris, presently the largest of the TNOs, has an apparent motion of about 27 arc seconds per day – although for a half year, the Earth’s orbital motion slows and retrogrades Pluto’s apparent motion. The 27 arc seconds is approximately 1/60th the width of a full Moon. So, from one night to the next, TNOs can travel as much...

And today (Dec. 1) comes a special day for Dawn — when it turns its cameras to Ceres to capture the asteroid, which will appear about nine pixels across. The reason? Besides scientific curiosity, it turns out to be a perfect calibration target, according to NASA. “One final calibration of the science camera is needed before arrival at Ceres,” wrote Marc Rayman, the mission director at the Jet Propulsion Laboratory, in a recent blog post. “To accomplish it, the camera needs to take pictures of a target that appears just a few pixels across. The endless sky that surrounds our...

The spacecraft has been sleeping quietly for weeks in its last great hibernation before the dwarf planet close encounter in July. On Saturday (Dec. 6), the NASA craft will open its eyes and begin preparations for that flyby. How cool will those closeups of Pluto and its moons look? A hint comes from a swing New Horizons took by Jupiter in 2007 en route. It caught a huge volcanic plume erupting off of the moon Io, picked up new details in Jupiter’s atmosphere and gave scientists a close-up of a mysterious “Little Red Spot.”

NASA's New Horizons spacecraft is set to awake on Dec. 6 from the last of its 18 hibernation periods and prepare for its initial approach towards Pluto, which will take place on Jan. 15. The spacecraft is scheduled to come as close as 6,200 miles from the surface of Pluto on July 14, 2015 -- the closest any man-made object has come to the dwarf planet. The mission marks the first visit outside Neptune's orbit to the Kuiper Belt, which consists of Pluto and thousands of objects that have not yet been identified, according to Spaceflight Now, a space news...

NASA's New Horizons spacecraft is set to awake on Dec. 6 from the last of its 18 hibernation periods and prepare for its initial approach towards Pluto, which will take place on Jan. 15. The spacecraft is scheduled to come as close as 6,200 miles from the surface of Pluto on July 14, 2015 -- the closest any man-made object has come to the dwarf planet.

Now here’s something I guarantee you’ve never seen before: a video of the dwarf planet Pluto and its largest moon Charon showing the two distinctly separate worlds actually in motion around each other! Captured by the steadily-approaching New Horizons spacecraft from July 19–24, the 12 images that comprise this animation were acquired with the Long Range Reconnaissance Imager (LORRI) instrument from distances of 267 million to 262 million miles (429 million to 422 million km) and show nearly a full orbital rotation. ... Pluto and Charon are seen circling a central gravitational point known as the barycenter, which accounts for...