No Planet X needed
The uncertainty of science: New computer models now suggest that the orbits of the known Kuiper Belt objects can be explained without the need for the theorized large Planet X.
The weirdly clustered orbits of some far-flung bodies in our solar system can be explained without invoking a big, undiscovered “Planet Nine,” a new study suggests.
The shepherding gravitational pull could come from many fellow trans-Neptunian objects (TNOs) rather than a single massive world, according to the research.
“If you remove Planet Nine from the model, and instead allow for lots of small objects scattered across a wide area, collective attractions between those objects could just as easily account for the eccentric orbits we see in some TNOs,” study lead author Antranik Sefilian, a doctoral student in the Department of Applied Mathematics and Theoretical Physics at Cambridge University in England, said in a statement.
When you think about it, having many many scattered small objects in the Kuiper Belt makes much more sense than a few giant planets. Out there, it would be difficult for large objects to coalesce from the solar system’s initial accretion disk. The density of material would be too low. However, you might get a lot of small objects from that disk, which once formed would be too far apart to accrete into larger planets.
The use of the term “Planet Nine” by these scientists however is somewhat annoying, and that has less to do with Pluto and more to do with the general understanding of what it means to be a planet that has been evolving in the past two decades. There are clearly more than eight planets known in the solar system now. The large moons of the gas giants as well as the larger dwarf planets, such as Ceres, have been shown to have all the complex features of planets. And fundamentally, they are large enough to be spheres, not misshaped asteroids.
On Christmas Eve 1968 three Americans became the first humans to visit another world. What they did to celebrate was unexpected and profound, and will be remembered throughout all human history. Genesis: the Story of Apollo 8, Robert Zimmerman's classic history of humanity's first journey to another world, tells that story, and it is now available as both an ebook and an audiobook, both with a foreword by Valerie Anders and a new introduction by Robert Zimmerman.
The ebook is available everywhere for $5.99 (before discount) at amazon, or direct from my ebook publisher, ebookit. If you buy it from ebookit you don't support the big tech companies and the author gets a bigger cut much sooner.
The audiobook is also available at all these vendors, and is also free with a 30-day trial membership to Audible.
"Not simply about one mission, [Genesis] is also the history of America's quest for the moon... Zimmerman has done a masterful job of tying disparate events together into a solid account of one of America's greatest human triumphs."--San Antonio Express-News
The uncertainty of science: New computer models now suggest that the orbits of the known Kuiper Belt objects can be explained without the need for the theorized large Planet X.
The weirdly clustered orbits of some far-flung bodies in our solar system can be explained without invoking a big, undiscovered “Planet Nine,” a new study suggests.
The shepherding gravitational pull could come from many fellow trans-Neptunian objects (TNOs) rather than a single massive world, according to the research.
“If you remove Planet Nine from the model, and instead allow for lots of small objects scattered across a wide area, collective attractions between those objects could just as easily account for the eccentric orbits we see in some TNOs,” study lead author Antranik Sefilian, a doctoral student in the Department of Applied Mathematics and Theoretical Physics at Cambridge University in England, said in a statement.
When you think about it, having many many scattered small objects in the Kuiper Belt makes much more sense than a few giant planets. Out there, it would be difficult for large objects to coalesce from the solar system’s initial accretion disk. The density of material would be too low. However, you might get a lot of small objects from that disk, which once formed would be too far apart to accrete into larger planets.
The use of the term “Planet Nine” by these scientists however is somewhat annoying, and that has less to do with Pluto and more to do with the general understanding of what it means to be a planet that has been evolving in the past two decades. There are clearly more than eight planets known in the solar system now. The large moons of the gas giants as well as the larger dwarf planets, such as Ceres, have been shown to have all the complex features of planets. And fundamentally, they are large enough to be spheres, not misshaped asteroids.
On Christmas Eve 1968 three Americans became the first humans to visit another world. What they did to celebrate was unexpected and profound, and will be remembered throughout all human history. Genesis: the Story of Apollo 8, Robert Zimmerman's classic history of humanity's first journey to another world, tells that story, and it is now available as both an ebook and an audiobook, both with a foreword by Valerie Anders and a new introduction by Robert Zimmerman.
The ebook is available everywhere for $5.99 (before discount) at amazon, or direct from my ebook publisher, ebookit. If you buy it from ebookit you don't support the big tech companies and the author gets a bigger cut much sooner.
The audiobook is also available at all these vendors, and is also free with a 30-day trial membership to Audible.
"Not simply about one mission, [Genesis] is also the history of America's quest for the moon... Zimmerman has done a masterful job of tying disparate events together into a solid account of one of America's greatest human triumphs."--San Antonio Express-News
tangentially related-
nicely done computer simulation
Simulating Solar System Formation
California Academy of Sciences 2016
[excerpt from their Planetarium show]
https://youtu.be/yXq1i3HlumA
4:21
Looney Tunes Duck Dodgers
“Planet X”
https://youtu.be/rh5G6RUgjiM
2:22
To pick a nit.
Didn’t the term “Planet X” come from when there were nine planets? Not because ‘X’ is cool but, because X is the Roman numeral 10.
The new mystery planet should be, if anything, IX.
Yeah, I’m a Roman numeral nerd…
I thought that “Planet X” referred to the original search for further planets after Neptune was discovered, because the action of Neptune couldn’t explain perturbations in the orbit of Uranus. “X” meaning “unknown”
The Search for Planet X
https://www.amazon.com/Search-Planet-X-Paperback/dp/B000IRWOG8
It would be horrendous if we reach a day when moons are labeled planets. It is bad enough they demoted Pluto.
I still prefer the terms, terrestrial, gas giants and Plutanoids for the rough classification of planets!
Well, moons (at least those which have reached hydrostatic equilibrium) really just a kind of planet.
If Ganymede were out there in lone orbit around the Sun, it would be called a “planet” – even by the IAU – without a second thought.