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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,...

A planet is a planet wherever it resides, right? Dave Eicher examines the case of the icy world.In 1930 a young astronomer from Kansas, employed as an observer at Lowell Observatory in Arizona, discovered Pluto. It was the first planet in the solar system to have been discovered since 1846, when astronomers in Germany detected Neptune. Clyde Tombaugh, just 24 at the time, was hailed as a hero, Disney named a cartoon dog after the new planet, and for 76 years the solar system was a happy place. And then, in 2006, the International Astronomical Union (IAU) reconsidered Pluto’s status....

There’s something odd floating around in the outer solar system. Actually, there’s lots of odd things floating around in the outer solar system, but 2002 UX25 is one of the most baffling. The mid-sized Kuiper belt object (KBO) measures 650 kilometers (400 miles) across, and yet it has a density less than water (less than 1 gram per cubic centimeter). Yes, if you put it in a huge bathtub, 2002 UX25 would float. ...planetary scientist Mike Brown, of the California Institute of Technology (Caltech) in Pasadena, has taken a measure of 2002 UX25′s density and discovered that it is “the...

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....

Data from a spacecraft orbiting Earth has revealed ripple structures in the termination shock and heliopause: shifting regions of space that mark one of the boundaries between the space inside the Solar System, and...interstellar space. ...Sun affects the space around it...solar wind, a constant supersonic flow of ionized plasma. It blows out past the planets and the Kuiper Belt, eventually petering out in the great emptiness between the stars. The point at which this flow falls below the speed at which sound waves can travel through the diffuse interstallar medium is called the termination shock, and the point at which...

In their studies, the team analyzed the effects of what is called the ‘Kozai mechanism,’ which is related to the gravitational perturbation that a large body exerts on the orbit of another much smaller and further away object. They looked at how the highly eccentric comet 96P/Machholz1 is influenced by Jupiter (it will come near the orbit of Mercury in 2017, but it travels as much as 6 AU at aphelion) and it may “provide the key to explain the puzzling clustering of orbits around argument of perihelion close to 0° recently found for the population of ETNOs,” the team...

Scholz's star -- named after the German astronomer who discovered it -- approached less than a light-year from the Sun. Nowadays it is almost 20 light-years away, but 70,000 years ago it entered the Oort cloud, a reservoir of trans-Neptunian objects located at the confines of the solar system. ... Now two astronomers from the Complutense University of Madrid, the brothers Carlos and Raúl de la Fuente Marcos, together with the researcher Sverre J. Aarseth of the University of Cambridge (United Kingdom), have analyzed for the first time the nearly 340 objects of the solar system with hyperbolic orbits (very...

Unravel the cosmic enigma with our latest video on the elusive "Planet Nine"! Join the quest as astronomers explore gravitational hints, peculiar orbits, and groundbreaking techniques in the relentless search.Are We about to Discover a New Planet in Our Solar System? | 21:46Astrographics | 44.6K subscribers | 329,973 views | February 7, 2024

One of Jupiter's tenuous rings can be seen in this infrared image. (NASA/ESA/CSA/STScI/Judy Schmidt) Given its similarities to its neighbor, Saturn, it seems natural to ask why Jupiter doesn't also have a magnificent, extensive system of visible rings. Alas, it's not the reality. While Jupiter does have rings, they're thin, tenuous, flimsy things of dust, visible only when back-lit by the Sun. According to new research, these discount rings lack bling because Jupiter's posse of chonky Galilean moons keep discs of rock and dust from accumulating the way they do around Saturn. "It's long bothered me why Jupiter doesn't have...

Rather, the comet's behavior is probably typical for comets making their first trip toward the sun — we just haven't been able to observe it before. "What makes this comet special is that it was discovered early," Jewitt said. "We've been able to follow the way the comet changes with distance from the sun over a much larger range than has ever been done before." Comet K2 comes from even farther away than the Kuiper Belt, Jewitt said. The comet's original home was most likely the Oort Cloud, the repository of comets and planetary fragments that extends from 2,000 to...

“If Planet Nine is real, it would be on such an odd orbit and so far out in the outer Solar System, that it would really challenge our ideas of planet formation and dynamics,” Ann-Marie Madigan, assistant professor of astrophysics... Madigan isn’t searching for just one planet — she’s looking for an entire belt of celestial objects. Like Planet Nine, this proposed Zderic-Madigan, or ZM, belt would be really out there, far beyond the Kuiper belt, with some of its closest bodies being more than twice as far from the Sun as Pluto at perihelion. Unlike the Kuiper belt, this...

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...

Centaurs are minor planets thought to have originated in the outer region of our Solar System known as the Kuiper Belt. Active centaurs enigmatically display prominent comet-like features such as comae or tails even though they orbit in the gas giant region where it is too cold for water to readily sublimate. Only 18 active centaurs have been identified since 1927 and, consequently, the underlying activity mechanisms are still poorly understood. 2014 OG392 orbits between 10 and 15 AU (astronomical units) where its equilibrium temperature would be around minus 213 degrees Celsius (minus 351 degrees Fahrenheit). Chandler and colleagues initially...

A new paper describes how the researchers connected the moving dots to find the new TNOs, and also says this new approach could help look for the hypothetical Planet Nine and other undiscovered worlds. The Dark Energy Survey (DES) is designed to probe the origin of the accelerating universe and help uncover the nature of dark energy by measuring the 14-billion-year history of cosmic expansion with high precision. It studies galaxies and supernovas and precisely tracks their movements. This survey has been active since 2013, using the 4-meter Blanco Telescope located at Cerro Tololo Inter-American Observatory (CTIO) in Chile. The...

Ultima Thule, the farthest cosmic body ever visited by a spacecraft, has been officially renamed Arrokoth, or "sky" in the Native American Powhatan and Algonquian languages, following a significant backlash over the old name's Nazi connotations. The icy rock, which orbits in the dark and frigid Kuiper Belt about a billion miles beyond Pluto, was visited by the NASA spaceship New Horizons in January this year, with the first detailed images showing it consisted of two spheres stuck together in the shape of a snowman. Its technical designation is 2014 MU69 but the New Horizon team initially nicknamed it Ultima...

A dwarf planet discovered over a decade ago is the largest body we know of in our solar system without a proper name – but that’s about to change. Meg Schwamb, an astronomer at Gemini Observatory in Hawaii, and her colleagues have opened a public vote to name the distant world, which is currently known only as 2007 OR10. They have selected three potential names that fit the International Astronomical Union’s (IAU) rules on official names for minor planets, and will recommend the winner to the IAU, which will then select the formal name. So why now, instead of when...

It's a large moon, the seventh largest in our solar system, and scientists think it was born in the Kuiper Belt before falling into its current location in orbit around the most distant planet. ...Procktor and her colleagues believe they can photograph the moon's entire surface in a single pass. ...On its way past Triton, the spacecraft's flight would be timed in order to see in sunlight the 60 percent or so of its surface that Voyager 2 couldn't see. After the initial approach, the spacecraft would turn its camera back to recapture the 40 percent of the surface Voyager...

The records include dates and times, Cesario said, which makes them useful to modern-day astronomers. Planet Nine, if it exists, would have about 10 times the mass of Earth and orbit 20 times farther from the sun than Neptune does... Scientists suspect the existence of Planet Nine because it would explain some of the gravitational forces at play in the Kuiper Belt, a stretch of icy bodies beyond Neptune. But no one has been able to detect the planet yet, though astronomers are scanning the skies for it with tools such as the Subaru Telescope on Hawaii's Mauna Kea volcano....

At the furthest reaches of the solar system, 2019 will start off with exploration. NASA has given the final green light to its New Horizons spacecraft for a January 1st flyby of Ultima Thule, an object in the Kuiper Belt around a billion miles beyond Pluto. It will be the most distant planetary flyby in human history. Before giving the okay, NASA wanted to make sure that it wasn't passing up any other opportunities for either study or disaster in the area—rings, small moons, and anything else that a probe like New Horizons might want to observe. Pushing through the...

Act Two of the 12-year-old New Horizons mission to Pluto and the solar system’s icy Kuiper Belt is heating up, with less than a month to go before NASA’s piano-sized spacecraft makes history’s farthest-out close encounter with a celestial object. The New Year’s flyby of a mysterious Kuiper Belt object (or objects) known as Ultima Thule (UL-ti-ma THOO-lee) follows up on the mission’s first act, which hit a climax three years ago with a history-making flyby of Pluto. Launched in 2006, New Horizons was never meant to be a one-shot deal. Even before the Pluto flyby, mission managers used the...