Astronomers probe origin of Planet 9

Posted: September 14, 2017 by oldbrew in Astronomy, solar system dynamics
Tags: ,

Where is Planet 9? [credit: NASA]

This may say something about what is not likely to be true about the mysterious, or mythical, Planet 9 but obviously it’s still all in the realms of theory. If it did form around the sun, how did it get to be so much further away from it than the known major planets in the solar system?

Astronomers at the University of Sheffield have shown that ‘Planet 9’ – an unseen planet on the edge of our solar system – probably formed closer to home than previously thought, reports

A team led by Dr Richard Parker from the University of Sheffield’s Department of Physics and Astronomy has found that Planet 9 is ‘unlikely’ to have been captured from another planetary system, as has previously been suggested, and must have formed around the sun.

The outskirts of the solar system have always been something of an enigma, with astronomers in the late 19th and early 20th centuries searching for a giant planet that wasn’t there, and the subsequent discovery of Pluto in 1930.

Pluto was downgraded in status to a ‘dwarf planet’ because astronomers discovered many other small objects – so-called Edgeworth-Kuiper Belt objects – at similar distances from the sun.

In 2016 astronomers working in the USA postulated the presence of ‘Planet 9’ to explain the strange orbital properties of some Edgeworth-Kuiper Belt objects. But while it isn’t possible to directly observe Planet 9, it hasn’t stopped theorists from trying to work out how it got there.

Planet 9 is at least 10 times bigger than Earth, making it unlikely that it formed at such a large distance from the sun. Instead, it has been suggested it either moved there from the inner regions of the solar system, or it could have been captured when the sun was still in its birth star cluster. But a team, led by Dr Parker with colleagues from ETH Zurich, has shown that the capture scenario is extremely unlikely.

Researchers simulated the sun’s stellar nursery where interactions are common and found that even in conditions optimised to capture free-floating planets, only five-to-10 out of 10,000 planets are captured onto an orbit like Planet 9’s.

Dr Parker said: “We know that planetary systems form at the same time as stars, and when stars are very young they are usually found in groups where interactions between stellar siblings are common. Therefore, the environment where stars form directly affects planetary systems like our own, and is usually so densely populated that stars can capture other stars or planets.

“In this work, we have shown that – although capture is common – ensnaring planets onto the postulated orbit of Planet 9 is very improbable. We’re not ruling out the idea of Planet 9, but instead we’re saying that it must have formed around the sun, rather than captured from another planetary system.”

The study was published in Monthly Notices of the Royal Astronomical Society.

Source: Astronomers probe origin of Planet 9

  1. Curious George says:

    “Astronomers working in the USA postulated the presence of ‘Planet 9’ to explain the strange orbital properties of some Edgeworth-Kuiper Belt objects. But while it isn’t possible to directly observe Planet 9, it hasn’t stopped theorists from trying to work out how it got there.”

    The University of Sheffield should consider renaming the Department of Physics and Astronomy to Department of Astronomy and Climatology.

  2. ivan says:

    Curious George, don’t you mean the Department of Alchemy and Wishful Thinking?

  3. oldbrew says:

    Then there’s the Oort Cloud…

    The Oort cloud, (named after the Dutch astronomer Jan Oort), sometimes called the Öpik–Oort cloud, is a theoretical cloud of predominantly icy planetesimals believed to surround the Sun to as far as somewhere between 50,000 and 200,000 AU (0.8 and 3.2 ly).
    . . .
    Astronomers conjecture that the matter composing the Oort cloud formed closer to the Sun and was scattered far into space by the gravitational effects of the giant planets early in the Solar System’s evolution. Although no confirmed direct observations of the Oort cloud have been made
    [bold added]

  4. JB says:

    Astronomers will never unravel these “mysteries” (artifacts of their own presumptions) as long as they base their astronomical ideas on gravitation. They will also persist in entering blind alleys that lead to dead ends as long as they misuse computer models.

    Someday, should we all be so fortunate, the flaws of computer models will be acknowledged and cease being used for predictive purposes. Nearly a century ago Karl Popper outlined the problems with inductive logic, and theorists are still executing them.

    “…the construction of a full-scale working model of a language of science—one in which we could operate a real science such as physics—turns out a little difficult in practice; and for this reason we find them engaged in the construction of intricate working models in miniature—of vast systems of minute gadgets…the intricacy of the outfit bears no relation to its effectiveness, and practically no scientific theory of any interest can be expressed in these vast systems of minutiae. These model languages have no bearing on either science or common sense.”–preface, The Logic of Scientific Discovery

    The greatest unseen problem with computer models isn’t in the model itself, but in the hubris of the constructor.

  5. oldbrew says:

    Venus’ mysterious night side revealed
    September 15, 2017

    “This study challenges our current understanding of climate modelling and, specifically, the super-rotation, which is a key phenomenon seen at Venus,” says Håkan Svedhem, ESA Project Scientist for Venus Express.

    Read more at:

  6. ivan says:

    As an aside to your comment about climate modelling oldbrew, we have snow on the top of my local mountain – a month earlier than last year.

    The models say it’s getting warmer – ha, ha.

  7. John H. Harmon says:

    We know almost nothing about the Oort cloud bodies, the night side of Venus or Earth’s climate system.
    Absent hubris, we will learn and our knowledge will increase our understanding. With hubris, we will build models based on guesses about processes, data and our own brilliance.
    You folks are as the “salt of the Earth” because you realize how little you know.
    Thanks for your efforts as you will advance Human-Kind.

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