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I have carried out a search for Planet 9 in the IRAS data. At the distance range proposed for Planet 9, the signature would be a 60 micron unidentified IRAS point source with an associated nearby source from the IRAS Reject File of sources which received only a single hours-confirmed (HCON) detection. The confirmed source should be detected on the first two HCON passes, but not on the third, while the single HCON should be detected only on the third HCON. I have examined the unidentified sources in three IRAS 60micron catalogues: some can be identified with 2MASS galaxies, Galactic...

Kathryn Volk and Renu Malhotra at the University of Arizona have noticed some strange movement out in the Kuiper belt…movement that they believe could suggest the existence of a tenth planet. ... Objects in the Kuiper belt are far enough away from the other major bodies in our solar system that the gravitational influence of the large planets doesn’t impact them (at least, not to a measurable degree); however, their movements can still be predicted, thanks to sky surveys and a host of advanced technologies. The search for Planet Nine has lead scientists to believe that it is orbiting around...

More clues about where to search for a possible ninth planet lurking in the fringes of our solar system are emerging from the Kuiper belt, the icy debris field beyond Neptune. And new calculations suggest that the putative planet might be brighter — and a bit easier to find — than once thought. Evidence for the existence of Planet Nine is scant, based on apparent alignments among the orbits of the six most distant denizens of the Kuiper belt (SN: 2/20/16, p. 6). Their oval orbits all point in roughly the same direction and lie in about the same plane,...

“I have announced this star as a comet, but since it is not accompanied by any nebulosity and, further, since its movement is so slow and rather uniform, it has occurred to me several times that it might be something better than a comet. But I have been careful not to advance this supposition to the public.” -Giuseppe Piazzi, discoverer of Ceres, the first Asteroid Out beyond Mars, but not quite out as far as Jupiter, a collection of thousands of rocky objects, ranging in size from pebbles all the way up to the size of Texas, lies the...

University of Arizona scientists have uncovered a curious case of missing asteroids. The main asteroid belt is a zone containing millions of rocky objects between the orbits of Mars and Jupiter. The scientists find that there ought to be more asteroids there than researchers observe. The missing asteroids may be evidence of an event that took place about 4 billion years ago, when the solar system's giant planets migrated to their present locations. UA planetary sciences graduate student David A. Minton and UA planetary sciences professor Renu Malhotra say missing asteroids is an important piece of evidence to support an...

Such interactions also caused the orbits of the major planets to migrate. Because the growing planets Saturn, Uranus and Neptune tossed more small bodies inward toward the orbit of Jupiter than out of the solar system, those planets migrated outward, to conserve the total angular momentum. But the much more massive planet Jupiter ejected most of the small bodies it encountered into the outer solar system and beyond, and it consequently migrated inward. When the solar system was forming, the Kuiper belt contained hundreds of times more mass than it does today. The objects now in the belt represent only...

Our solar system may have an outer "edge" just outside the orbit of Pluto, astronomers announced recently. Their results suggest that early in the history of the solar system, some event stripped away most of the planet-building material beyond 50 times Earth's distrance from the sun. Lynne Allen and Gary Bernstein, of the University of Michigan, and Renu Malhotra of the University of Arizona Lunar and Planetary Laboratory... searched 6 patches of sky, each about the size of the full moon, using a state-of-the-art electronic camera at the Cerro Tololo Inter-American Observatory in the Chilean Andes... These observations, in 1998...

A moderately massive early Sun has been proposed to resolve the so-called faint early Sun paradox. We calculate the time-evolution of the solar mass that would be required by this hypothesis, using a simple parametrized energy-balance model for Earth's climate. Our calculations show that the solar mass loss rate would need to have been 2-3 orders of magnitude higher than present for a time on the order of ~2 Gy. Such a mass loss history is significantly at variance (both in timescale and in the magnitude of the mass loss rates) with that inferred from astronomical observations of mass loss...

Astronomers using NASA's Spitzer Space Telescope have found evidence that dusty disks of planet-forming material tug on and slow down the young, whirling stars they surround. Young stars are full of energy, spinning around like tops in half a day or less. They would spin even faster, but something puts on the brakes. While scientists had theorized that planet-forming disks might be at least part of the answer, demonstrating this had been hard to do until now... Stars begin life as collapsing balls of gas that spin faster and faster as they shrink, like twirling ice skaters pulling in their...

The University of Arizona Lunar and Planetary Laboratory is launching its Fall 2009 Evening Lecture Series with talks on wandering solar system planets and searches for hazardous asteroids from Mount Lemmon... Planetary sciences professor Renu Malhotra will speak on "Migrating Planets" on Tuesday, Sept. 15. [whoops] Did the solar system always look the way it is now? New studies by Malhotra and others find that the outer planets -- Jupiter, Saturn, Uranus and Neptune -- were more tightly clustered in the early solar system, then moved away from each other. Malhotra's models show that as the solar system evolved, Jupiter...