Latest news with #dwarfplanet
Yahoo
05-07-2025
- Science
- Yahoo
What are dwarf planets — and how many are there?
When you buy through links on our articles, Future and its syndication partners may earn a commission. In 2006, Pluto was famously demoted from a planet to a dwarf planet. It remains the most famous dwarf planet today, but there are others in our solar system, including potentially hundreds that haven't been discovered yet. But what, exactly, is a dwarf planet? And how many dwarf planets are there? A dwarf planet is a celestial body that is smaller than a planet but bigger than an asteroid or other small rock in the solar system. They're not planets because they only meet two of the three criteria for something in space to be considered a true planet. A planet is defined by three qualities: It orbits the sun, it's mostly round, and it's massive enough for its gravity to have mostly kicked large objects from its orbit. Pluto and some other known dwarf planets meet the first two criteria but not the third because they orbit in the Kuiper Belt, a region beyond Neptune filled with small icy debris. When Pluto was first discovered in 1930, it (and other similar objects in the Kuiper Belt) were so far away and faint that they were really hard to spot, even with the most powerful telescopes at the time. Indeed, the very qualities that make something a dwarf planet make those objects particularly hard to detect. Related: James Webb telescope discovers 'a new kind of climate' on Pluto, unlike anything else in our solar system "There are a few things that work against us spotting them," Mathew Yu, an astronomer at UCLA, told Live Science in an email. "They are far away from the sun. The reflected light from them is faint as a result. Some have low reflectivity, making light reflecting off them fainter." Plus, "they move slowly across the sky due to their large distance from the sun," he added. "They go around the sun once every hundreds of Earth years. So their relative motions to the background stars are small. For astronomers with a limited observing time, these objects become hard to detect." Astronomers got a lot better at finding objects in the Kuiper Belt in the 1990s and 2000s as telescope technology improved. And once they could see a bit better, they noticed there were a lot more rocks out there with orbits similar to Pluto's. Between 2002 and 2005, astronomers found seven more particularly large rocks: Haumea, Makemake, Quaoar, Sedna, Orcus, Eris and Salacia. The International Astronomical Union (IAU) — the group of astronomers that decides on official names and terms for things in space — decided in 2006 that a new category was needed to describe these objects that were pretty big but not big enough to clear their orbits as a true planet does. Thus, the name "dwarf planet" was born. With eight named large rocks in the Kuiper Belt, you might think that means there are eight dwarf planets. However, not all astronomers agree on the number. "Accepted numbers range between around 10 to a few hundred in the Kuiper Belt alone," Yu said. "Some estimate that there may be up to tens of thousands of them beyond the Kuiper Belt." The IAU has officially recognized only five dwarf planets: Pluto, Haumea, Makemake and Eris in the Kuiper Belt, plus Ceres in the asteroid belt. We've sent space probes to only two of these: Pluto (visited by NASA's New Horizons) and Ceres (visited by NASA's Dawn), both of which flew by those bodies in 2015. Astronomers who observe dwarf planets, however, tend to recognize nine: the previous five, plus Quaoar, Sedna, Orcus and Gonggong. Gonggong was discovered in 2007 after the dwarf planet name change, but it wasn't confirmed until some new observations from NASA telescopes in 2016. The IAU is still considering proposals on these dwarfish bodies. RELATED STORIES —Watch newly discovered 'interstellar visitor' 3I/ATLAS shoot toward us in first livestream today (July 3) —'A completely new phenomenon': Astronomers spot a planet causing its star to constantly explode —James Webb telescope discovers tentacled 'jellyfish' galaxy swimming through deep space There are at least a handful more objects that have been proposed but need more observations to confirm their size and, therefore, dwarf planet status. And in June 2025, scientists proposed a new possible dwarf planet: 2017 OF201. Astronomers found this particularly faint object by searching through an old pile of data with new advanced algorithms. If you count all of the currently proposed dwarf planets plus the newcomer, that makes eighteen or more dwarf planets in the solar system — and that's just the ones we've seen. There are likely more out there, perhaps even hundreds or thousands, someday to be revealed as our telescopes keep getting better.
Gizmodo
01-07-2025
- Science
- Gizmodo
Experimental Propulsion Tech Could Reach Mysterious Planet Beyond Pluto in 10 Years
On November 14, 2003, astronomers spotted what was at the time the most distant known object orbiting the Sun. They called it Sedna after the Inuit goddess of the ocean. It's a cold, reddish dwarf planet that drifts billions of miles away from the Sun during its 10,000-year orbit before coming in for a relatively close approach to our star. Its next perihelion is happening in July 2076, and astronomers want to take advantage of this rare encounter by flying a mission to the mysterious object. A team of researchers from Italy suggests mission concepts that could reach Sedna in seven to 10 years using cutting-edge technology. In a paper available on the pre-print website arXiv, they illustrate two experimental propulsion concepts that involve a nuclear fusion rocket engine and a new take on solar sailing technology. The propulsion technologies could cut down travel time to Sedna by more than 50% compared to traditional methods of space travel, allowing scientists a unique opportunity to gather clues about the early formation of the solar system and probe the theoretical Oort Cloud. When it was discovered, Sedna was around 8 billion miles (13 billion kilometers) from the Sun. (Pluto, the most famous dwarf planet, has an average distance of 3.7 billion miles from the Sun.) Sedna is known as a Trans-Neptunian object, a group of objects that orbit the Sun farther out than Neptune. It has an extremely eccentric orbit: at its farthest distance, Sedna is 84 billion miles away from the Sun, or 900 times the distance between Earth and our star. During its closest approach, Sedna will be around 7 billion miles away from the Sun, nearly three times farther than Neptune. That's still far, but it's close enough for a spacecraft to reach the celestial object before it fades back into ultra-distant darkness. Spacecraft have traveled farther distances before. Voyager 1 and 2 started their interstellar journey in 1977 and have traveled 15 billion miles and 12.7 billion miles thus far. It took Voyager 2 around 12 years to reach Neptune. Based on current technology, scientists estimate it would take around 20-30 years to reach Sedna during its closest approach, while using Venus, Earth, Jupiter, and Neptune as gravity assists. That would mean the launch window to reach Sedna is fast approaching, with no clear plans yet in place. Instead, the researchers behind the new study suggest alternative methods to get us there faster. The first is the Direct Fusion Drive (DFD) rocket engine, which is currently under development at Princeton University's Plasma Physics Laboratory. The fusion-powered rocket engine would produce both thrust and electrical power from a controlled nuclear fusion reaction, providing more power than chemical rockets. 'The DFD presents a promising alternative to conventional propulsion, offering high thrust-to-weight ratio and continuous acceleration,' the researchers write in the paper. 'However, its feasibility remains subject to key engineering challenges, including plasma stability, heat dissipation, and operational longevity under deep-space radiation.' They add that, while advances are being made for fusion-based propulsion, it's still unclear whether it can support long-duration missions and provide power for onboard instruments. The second concept builds on existing solar sail technology, which is still experimental in its own right. Solar sails are powered by photons from the Sun, harnessing energy produced by light and using it to propel spacecraft forward. The researchers suggest coating the solar sails with material that, when heated, releases molecules or atoms and provides propulsion in a process known as thermal desorption. The solar sail, assisted by Jupiter's gravity, could reach Sedna in seven years due to its ability to continuously accelerate without the need to carry heavy fuel, according to the paper. The idea does come with its own set of challenges. 'While solar sailing has been extensively studied for deep-space applications, its feasibility for a Sedna mission requires assessment in terms of long-duration structural integrity, propulsion efficiency, and power availability for science operations,' the paper reads. Despite a slight time advantage, the solar sail mission would only allow for a flyby of Sedna, while the DFD engine could insert a spacecraft into the dwarf planet's orbit for a longer mission. Either mission would provide us with the first direct observations of the previously unexplored region and help scientists better understand the larger boundary that houses the solar system.
Forbes
15-06-2025
- Science
- Forbes
New Pluto-Like Planet Discovered In Solar System — What To Know
Astronomers have found a distant celestial body — potentially a dwarf planet — orbiting the sun from more than twice as far as Pluto. Found by astronomers at the Institute for Advanced Study in Princeton, New Jersey, it's one of the most distant solar system bodies observed with optical telescopes. It takes 25,000 years to orbit the sun — and it could be the first of many new objects to be found in the outer solar system. This is an artist's concept of a craggy piece of solar system debris that belongs to a class of ... More bodies called trans-Neptunian objects (TNOs). 2017 OF201 is estimated to be 435 miles (700 kilometers) in diameter. That's smaller than Pluto's 1,477 miles (2,377 kilometers), but if its size is confirmed using radio telescopes, 2017 OF201 will become the largest object in the outer solar system found in more than a decade. It's classed as an 'extreme' trans-Neptunian object, which is an icy body orbiting beyond Neptune in the solar system. The largest TNOs known are Eris, followed by Pluto, Haumea, Makemake and Gonggong. Researchers identified it in 19 different exposures captured over seven years by the Dark Energy Camera (on the summit of Cerro Tololo, Chile) and the Canada France Hawaii Telescope (near the summit of Mauna Kea on Hawaii's Big Island). Image showing the current location of Pluto, Neptune, and 2017 OF201. 2017 OF201 is a rare object because of its size, but also its extreme orbit. 'The object's aphelion — the farthest point on the orbit from the sun — is more than 1,600 times that of the Earth's orbit,' said Sihao Cheng at the Institute for Advanced Study's School of Natural Sciences. 'Meanwhile, its perihelion — the closest point on its orbit to the sun — is 44.5 times that of the Earth's orbit, similar to Pluto's orbit.' It takes 2017 OF201 about 25,000 years to complete one orbit of the sun, which suggests a chaotic past. 'It must have experienced close encounters with a giant planet, causing it to be ejected to a wide orbit,' said Yang. "It's possible that this object was first ejected to the Oort cloud, the most distant region in our solar system, which is home to many comets, and then sent back." 2017 OF201 exists at the edge of the solar system in what's known as the Kuiper Belt, a vast ring-shaped region beyond the orbit of Neptune. It was thought that the Kuiper Belt was largely empty of large objects — but 2017 OF201 indicates that is not the case. That's underscored by the fact that 2017 OF201 spends only 1% of its orbital time close enough to the inner solar system to be detectable. 'The presence of this single object suggests that there could be another hundred or so other objects with similar orbit and size; they are just too far away to be detectable now,' said Cheng. 'Even though advances in telescopes have enabled us to explore distant parts of the universe, there is still a great deal to discover about our own solar system.' In September 2004, scientists announced that they had uncovered 11 new objects beyond the accepted edge of the Kuiper Belt. They were found in alcluster while using the 8.2-meter Subaru Telescope in Hawaii to find new targets for NASA's New Horizons spacecraft, which left Earth in 2006 and conducted the only ever flyby of Pluto in 2015 before entering the Kuiper Belt.
Yahoo
04-06-2025
- General
- Yahoo
Planet Nine? Not quite, but some astronomers think they've spotted a new dwarf planet
A possible new dwarf planet has been discovered at the edge of our solar system, so far-flung that it takes around 25,000 years to complete one orbit around the sun. The object, known as 2017 OF201, was found by researchers at the Institute for Advanced Study and Princeton University who were searching for 'Planet Nine,' a hypothetical planet larger than Earth that is thought to orbit beyond Neptune. Some astronomers theorize that a mysterious ninth planet, which so far remains undetected, could explain an unusual clustering of objects and other anomalies observed in the outer solar system. In searching for the elusive Planet Nine, researchers instead turned up a different resident in our cosmic backyard. 'It's not very different from how Pluto was discovered,' said Sihao Cheng, a member at the Institute for Advanced Study who led the research team. 'This project was really an adventure.' If confirmed, the newfound dwarf planet would be what Cheng calls an 'extreme cousin' of Pluto. The findings were published on the preprint website arXiv and have not yet been peer-reviewed. Cheng and his colleagues estimate that 2017 OF201 measures about 435 miles across — significantly smaller than Pluto, which measures nearly 1,500 miles across. A dwarf planet is classified as a celestial body that orbits the sun that has enough mass and gravity to be mostly round, but unlike other planets, has not cleared its orbital path of asteroids and other objects. Eritas Yang, one of the study's co-authors and a graduate student at Princeton University, said that one of 2017 OF201's most interesting features is its extremely elongated orbit. At its farthest point from the sun, the object is more than 1,600 times more distant than the Earth is to the sun. The researchers found the dwarf planet candidate by meticulously sifting through a huge data set from a telescope in Chile that was scanning the universe for evidence of dark energy. By cobbling together observations over time, the researchers identified a moving object with migrations that followed a clear pattern. 2017 OF201 is likely one of the most distant visible objects in the solar system, but its discovery suggests there could be other dwarf planets populating that region of space. 'We were using public data that has been there for a long time,' said Jiaxuan Li, a study co-author and a graduate student at Princeton University. 'It was just hidden there.' Li said the object is close to the sun at the moment, which means the researchers need to wait about a month before they can conduct follow-up observations using ground-based telescopes. The scientists are also hopeful that they can eventually secure some time to study the object with the Hubble Space Telescope or the James Webb Space Telescope. In the meantime, Cheng said he hasn't given up searching for Planet Nine. The new discovery, however, may throw a wrench into some long-standing theories of the planet's existence. The hypothesis behind Planet Nine is that a planet several times the size of Earth in the outer solar system could explain why a group of icy objects seem to have unusually clustered orbits. 'Under the influence of Planet Nine, all objects that do not have this specific orbital geometry will eventually become unstable and get kicked out of the solar system,' Yang said. 2017 OF201's elongated orbit makes it an outlier from the clustered objects, but Yang's calculations suggest that the orbit of 2017 OF201 should remain stable over roughly the next billion years. In other words, 2017 OF201 likely would not be able to remain if Planet Nine does exist. But Yang said more research is needed, and the discovery of the new dwarf planet candidate is not necessarily a death knell for Planet Nine. For one, the simulations only used one specific location for Planet Nine, but scientists don't all agree on where the hypothetical planet lurks — if it's there at all. Konstantin Batygin, a professor of planetary science at the California Institute of Technology, proposed the existence of Planet Nine in a study published with his Caltech colleague Mike Brown in 2016. He said the discovery of 2017 OF201 doesn't prove or disprove the theory. The objects in the outer solar system that are likely to show a footprint of Planet Nine's gravity, Batygin said, are the ones where the closest points on their orbits around the sun are still distant enough that they don't strongly interact with Neptune. 'This one, unfortunately, does not fall into that category,' Batygin told NBC News. 'This object is on a chaotic orbit, and so when it comes to the question of 'What does it really mean for Planet Nine?' The answer is not very much, because it's chaotic.' Batygin said he was excited to see the new study because it adds more context to how objects came to be in the outer solar system, and he called the researchers' efforts mining public data sets 'heroic.' Cheng, for his part, said he hasn't abandoned hope of finding Planet Nine. 'This whole project started as a search for Planet Nine, and I'm still in that mode,' he said. 'But this is an interesting story for scientific discovery. Who knows if Planet Nine exists, but it can be interesting if you're willing to take some risks.' This article was originally published on
Malay Mail
31-05-2025
- General
- Malay Mail
Potential dwarf planet 2017 OF201 discovered in solar system's distant reaches
WASHINGTON, June 1 — Scientists have identified an object about 435 miles (700 km) wide inhabiting the frigid outer reaches of our solar system that might qualify as a dwarf planet, spotting it as it travels on a highly elongated orbital path around the sun. The researchers called it one of the most distant visible objects in our solar system, and said its existence indicates that a vast expanse of space beyond the outermost planet Neptune and a region called the Kuiper Belt may not be deserted, as long thought. The Kuiper Belt is populated by numerous icy bodies. Given the name 2017 OF201, the object falls into a category called trans-Neptunian objects that orbit the sun at a distance beyond that of Neptune. The object takes about 25,000 years to complete a single orbit of the sun, compared to 365 days for Earth to do so. The researchers said 2017 OF201 was identified in observations by telescopes in Chile and Hawaii spanning seven years. 'It is potentially large enough to qualify as a dwarf planet. Its orbit is very wide and eccentric, which means it experienced an interesting orbital migration path in the past,' said astrophysicist Sihao Cheng of the Institute for Advanced Study in Princeton, New Jersey, who led the study with collaborators Jiaxuan Li and Eritas Yang, graduate students at Princeton University. Its size is estimated to be a bit smaller than Ceres, which is the smallest of the solar system's five recognized dwarf planets and has a diameter of about 590 miles (950 km). Pluto, the largest of those dwarf planets, has a diameter of about 1,477 miles (2,377 km). The mass of 2017 OF201 is estimated to be about 20,000 times smaller than Earth's and 50 times smaller than Pluto's. 'We don't know the shape yet. Unfortunately it is too far away and it is a bit difficult to resolve it with telescopes,' Cheng said. 'Its composition is totally unknown yet, but likely similar to other icy bodies.' The discovery was announced by the Minor Planet Center of the International Astronomical Union, an international organization of astronomers, and detailed in a study posted on the open-access research site arXiv. The study has not yet been peer reviewed. Earth's orbital distance from the sun is called an astronomical unit. 2017 OF201 is currently located at a distance of 90.5 astronomical units from the sun, meaning 90.5 times as far as Earth. But at its furthest point during its orbit, 2017 OF201 is more than 1,600 astronomical units from the sun, while the closest point on its orbit is about 45 astronomical units. That means it sometimes is closer to the sun than Pluto, whose orbital distance ranges from 30 to 49 astronomical units as it travels an elliptical path around the sun. The researchers suspect that the extreme orbit of 2017 OF201 may have been caused by a long-ago close encounter with the gravitational influence of a giant planet. 'We still don't know much about the solar system far away because currently it is difficult to directly see things beyond about 150 astronomical units,' Cheng said. 'The presence of this single object suggests that there could be another hundred or so other objects with similar orbit and size. They are just too far away to be detectable right now.' The five dwarf planets recognized by the International Astronomical Union are, in order of distance from the sun: Ceres, which is the largest object in the asteroid belt between Mars and Jupiter, then Pluto, Haumea, Makemake and Eris, which all orbit beyond Neptune. The organization defines a planet and a dwarf planet differently. A planet must orbit its host star - in our case the sun - and must be mostly round and sufficiently large that its gravitational strength clears away any other objects of similar size near its orbit. A dwarf planet must orbit the sun and be mostly round but it has not cleared its orbit of other objects. Cheng said the discovery of 2017 OF201 has implications for hypotheses involving the potential existence of a ninth planet in our solar system, dubbed Planet X or Planet Nine. This is because 2017 OF201's orbit does not follow the pattern exhibited by other known trans-Neptunian objects, which tend to cluster together. Some scientists had hypothesized that such clustering was caused by the gravity of a yet-to-be discovered planet. 'The existence of 2017 OF201 as an outlier to such clustering could potentially challenge this hypothesis,' Cheng said. — Reuters
