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Are comets born in great swarms? The puzzling abundance of comets in short solar orbits has led a pair of astronomers to suggest that they are fragments of larger bodies that crumbled as they entered the inner solar system. Short-period comets take less than 200 years to circle the sun and are thought to originate in the Kuiper belt of icy objects beyond Neptune. Some Kuiper-belt objects (KBOs) are in vulnerable orbits that allow the gravity of the outer planets to tug them inwards, where the sun's heat turns them into comets. However, there seem to be too few KBOs...

A FOCAL Mission into the Oort Cloud by Paul Gilster on November 15, 2010 After all this time, IÂ’m still trying to wrap my head around the idea of massive objects in space as lenses, their distortion of spacetime offering the ability to see distant objects at huge magnification. On Friday we saw how the lensing effect caused by galactic clusters can be used to study dark energy. And consider the early results from the Herschel-ATLAS project, conducted by ESAÂ’s Herschel Space Observatory. Herschel is scanning large areas of the sky in far-infrared and sub-millimeter light. Many of its...

The transit method — observing a distant planet as it moves in front of its star as seen from Earth — is a prime tool for exoplanet detection. But transits are hardly limited to planets around their primaries. The Taiwanese-American Occultation Survey (TAOS) is demonstration of that, an attempt to find tiny Kuiper Belt objects (KBOs) in the range between 0.5 and 28 kilometers. As you would imagine, at a distance like this such objects cannot be seen directly, but an occultation — the dimming of a star when one of the KBOs passes in front of it —...

the Taiwanese-American Occultation Survey (TAOS), spent two years periodically photographing portions of the sky to look for small chunks of rock and ice orbiting beyond Neptune, in a region of the solar system called the Kuiper Belt. The survey targeted Kuiper Belt objects (KBOs) with sizes between 2 miles (3 km) and 17 miles (28 km). Since such objects are too small to see directly, the survey watched for stars to dim as KBOs passed in front of and occulted them. After accumulating more than 200 hours of data watching for stellar flickers lasting a second or less, TAOS did...

...a tiny, icy toehold just one-third of a mile wide. The discovery, made by a team of astronomers scouring Hubble Space Telescope observations, sets a new record for the smallest Kuiper Belt object found. Previously, the smallest known Pluto sibling was a 30-mile-wide Kuiper Belt object... Based on the number of known objects in the Kuiper Belt, scientists would have expected to find between 30 and 100 tiny bodies in their analysis of 50,000 guide stars observed by Hubble. So far, the team has only looked at 30 percent of the available Hubble data. "We only found one," Schlichting said....

Our understanding of the Kuiper belt has changed dramatically in these past five years. The best example of this change comes, I think, from the discovery of a large Kuiper belt object that was announced just a few days ago... But, by decoding the numbers, I could tell it was something that had just been discovered a few days before. Like anyone else, my first attempt to know more was a quick trip to Google. Ah ha! A new large Kuiper belt object found from a telescope Chile, by David Rabinowitz! Yes, the same David Rabinowitz from the Haumea discovery....

If David J. Tholen (University of Hawaii) is right, Pluto was probably hit by a small Kuiper Belt object in the not-too-distant past. One consequence of that collision, he argues, is seen in the planet's motion -- Pluto and its satellite Charon now waltz around each other in slightly out-of-round orbits. And since tidal forces in the tight planet-moon system should damp out any deviations from purly circular orbits within 10 million years or so, the impact must have occurred relatively recently. "It could have happened a century ago," Tholen says... Tholen and Marc W. Buie (Lowell Observatory)... found an...

We have completed a low-inclination ecliptic survey for distant and slow-moving bright objects in the outer solar system. This survey used data taken over 34 months by the University of Arizona's Spacewatch Project based at Steward Observatory, Kitt Peak. Spacewatch revisits the same sky area every three to seven nights in order to track cohorts of main-belt asteroids. This survey used a multiple-night detection scheme to extend our rate sensitivity to as low as 0.012 arcsec hr-1. When combined with our plate scale and flux sensitivity (V21), this survey was sensitive to Mars-sized objects out to 300 AU and Jupiter-sized...

News leaks about the planet definition began to spout late this week, as the authors prepared to present a draft resolution to the IAU's executive committee Sunday in Prague. The IAU is the official arbiter of all issues related to astronomical nomenclature. In a story that aired Thursday, unnamed sources told National Public Radio the proposed definition would include Pluto in a new class of small planets. A source also told the Rocky Mountain News on Thursday that a member of the seven-person definition panel said Pluto will remain a planet. IAU Vice President Bob Williams described the reports as...

Something spectacular may happen in 2012. New Horizons, a NASA space craft with a probe will travel at 26,700mph over four billion miles to Pluto. It will be in close proximity of Pluto by 2012. New Horizons probe will travel faster than any previous spacecraft on its journey to the planet farthest from the Sun, its moon Charon and the mysterious, icy Kuiper Belt. Relatively little is known about the ninth planet Pluto. It is an unknown zone of the solar system. Many scientists have started believing that Pluto will surprise all in the earth by 2012. There are fair...

One leading proposal would define a planet as any object whose diameter exceeds 2,000 kilometers and that is round as a result of gravity, criteria that would encompass anything Pluto-size or larger, including Xena. But that doesn't sit well with some astronomers, who are irked that the scrawny iceball with the cockeyed orbit earned membership into the club in the first place. "Pluto is an impostor," says Harvard astronomer Brian Marsden, a member of the IAU committee. "The simplest thing is to get rid of it and say we've got eight."

BALTIMORE - Pluto has three moons, not one, new images from the Hubble Space Telescope suggest. Pluto, discovered as the ninth planet in 1930, was thought to be alone until its moon Charon was spotted in 1978. The new moons, more than twice as far away as Charon and many times fainter, were spotted by Hubble in May. While the observations have to be confirmed, members of the team that discovered the satellites said Monday they felt confident about their data. "Pluto and Charon are not alone, they have two neighbors," said Hal Weaver of the Johns Hopkins University Applied...

PASADENA, Calif. - Between feedings and diaper changes of his newborn daughter, Michael E. Brown may yet find an 11th planet. Once conducted almost exclusively on cold, lonely nights, observational astronomy these days is often done under bright California sunshine. When he has a few spare minutes, Dr. Brown, a professor of planetary astronomy at the California Institute of Technology, downloads images taken during a previous night by a robotically driven telescope at Palomar Observatory 100 miles away. Each night, the telescope scans a different swath of sky, photographing each patch three times, spaced an hour and a half apart....

At its conference this August, the International Astronomical Union (IAU) will make a decision that could see Pluto lose its status as a planet. For the first time, the organisation will be officially defining the word "planet", and it is causing much debate in the world of astronomy. There is only one thing that everyone seems to agree on: there are no longer nine planets in the Solar System. The debate has been brought to a head by the discovery of a potential 10th planet, temporarily named 2003 UB313 in January 2005. This new candidate planet is bigger than Pluto....

The two moons discovered around Pluto last year were likely formed from the same giant impact that created the planet’s much larger satellite, Charon, scientists say. The idea suggests that other Kuiper Belt Objects might also harbor multiple satellites and raises the possibility that Pluto is encircled by rings fashioned from debris ejected from the surface of the tiny moons. The two moons, called P1 and P2 for now, were discovered in May 2005 using the Hubble Space Telescope. Scientists now think the two moons are roughly 37 and 31 miles (60 and 50 km) in diameter. Charon has an...

For education and discussion only. Not for commercial use. WASHINGTON (Reuters) - It's the biggest thing found orbiting the sun since astronomers discovered Pluto in 1930, but please do not call it a planet. Call it Quaoar. At half the size of Pluto, Quaoar -- pronounced KWAH-o-ar -- is a large celestial object, but not large enough to be a planet, one of its discoverers said in a telephone interview. Quaoar's discovery also calls Pluto's planet status into question, said Mike Brown of the California Institute of Technology, who first detected the object on June 4. His findings were presented...

LOS ANGELES - The astronomers who claim to have discovered the 10th planet in the solar system have made another intriguing announcement: it has a moon. While observing the new, so-called planet from Hawaii last month, a team of astronomers led by Michael Brown of the California Institute of Technology spotted a faint object trailing next to it. Because it was moving, astronomers ruled it was a moon and not a background star, which is stationary. The moon discovery is important because it can help scientists determine the new planet's mass. In July, Brown announced the discovery of an icy,...