Planet Nine: How we’ll find the Solar System’s missing planet

Posted: September 23, 2019 by oldbrew in Astronomy, Celestial Mechanics, predictions, solar system dynamics
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The predicted ninth planet has so far proved elusive, with searches of 50 per cent of the sky in the range where it ‘should’ be having turned up nothing. But planetary theorists Mike Brown and Konstantin Batygin insist the evidence shows they are on the right track. Others talk of broken glass and fingerprints – shades of Sherlock Holmes.

Beyond Neptune, a handful of small worlds are moving in harmony.

Astronomers think they might be dancing to the tune of a third world lurking in the darkness, one that’s four times bigger than Earth and significant enough to be named our Solar System’s ninth planet.

Now they think they know exactly where to look for it, says Science Focus.

Look up at the night sky and find the famous three stars of Orion’s Belt. Then extend the line between them up and to the right towards the constellation of Taurus, The Bull. Halfway between them sits a small patch of otherwise unremarkable sky that could well be home to one of the most famous finds in astronomical history – a ninth planet orbiting the Sun.

It isn’t every day a new planet is discovered in the Solar System. In fact, by one measure, it has only happened twice before in all of human history with Uranus (1781) and Neptune (1846). All the other planets have been known since antiquity and were never really ‘discovered’.

Objects such as Ceres (the largest asteroid) and Pluto were once deemed part of the planet club, but have since had their membership revoked. William Herschel, Urbain Le Verrier, Johann Gottfried Galle and John Couch Adams are the only astronomers to ever find a new planet that is still considered as such.

That elite list may soon be about to grow. CalTech astronomers Mike Brown and Konstantin Batygin are among the frontrunners to join it.

Back in 2016 they went public with the radical notion that the roll call of planets orbiting the Sun isn’t finished. They had noticed a handful of small worlds beyond Neptune behaving mysteriously, and considered that perhaps a ninth planet could account for their strange motion.

“We were confident that another planet could explain the features of the outer Solar System,” says Batygin. They’ve been scouring the sky for this object, but so far it has escaped them. For now, this potential world goes by the moniker of Planet Nine. If and when it is discovered, it will be named after a Roman or Greek deity, just like the other planets.

Long-distance relationship

Planet Nine’s suggested existence is based on observations over the last decade with telescopes big enough to peer into the murky environs beyond the eight known planets. Studying this under-explored wilderness is a real challenge. We only see thanks to reflected sunlight, and for these trans-Neptunian objects (TNOs) that light has to undergo quite a journey.

The odyssey starts at the Sun, then travels out to a distance of more than 4,500,000,000km, before bouncing off an object and making the return trip to the Earth almost all the way back to the start. That light is also fading all the while, making it very faint and requiring a big telescope to collect it.

2012 VP113 orbit with solar system orbits [credit: Tomruen @ Wikipedia]

Take the 600-kilometre-wide object known as 2012 VP113. It sits 80 times further from the Sun than the Earth, meaning the light we see reflected from it is around 40 million times dimmer than normal sunlight. Despite travelling at 300,000 kilometres per second, light takes nearly a day to cover the full distance from the Sun to VP113 and back to the Earth.

It was the discovery of VP113 by astronomers Scott Sheppard and Chad Trujillo in 2014 that first flagged up the possibility of an undiscovered planet. They are another team currently hunting down Planet Nine.

Closer scrutiny of VP113’s path around the Sun showed that it shared orbital characteristics with another TNO called Sedna. The angle at which they approach the Sun is eerily similar. Our best theories of Solar System formation say that for each object this tilt should be random. So the fact that these two objects match arouses suspicion.

“They’re like the fingerprints and broken glass of a crime scene,” says Megan Schwamb from the Gemini Observatory in Hawaii and co-discoverer of several TNOs. “Who did it?”.

Continued here.

  1. JB says:

    “observations over the last decade with telescopes big enough to peer into the murky environs beyond the eight known planets” This ALL telescopes do, no matter their size. The problem has always been the light sensitivity of the detector.

    May I forever have egg on my face by declaring these folks will find everything they’re not interested in but the fabled 9th planet. The impediment to date is not technology, nor persistence in looking, but the mental model that leads them to conclude it is there at all.

  2. richard verney says:

    If it exists, it is unlikely to be a planet, since the probable reason why we are having difficulty locating it, is that it has failed to clear its orbit.

  3. oldbrew says:

    ‘In fact, all known Solar System bodies with semi-major axes over 150 AU and perihelia greater than Neptune’s have arguments of perihelion clustered near 340°±55°.’

    Doesn’t look random 🤔

  4. stpaulchuck says:

    Unicorn hunters are certain they will have photographic proof any day now. [*smirks behind hand*]

    Hey guys, what don’t you move off that and sort out the dark matter/dark energy issues? That should be much easier.

  5. oldbrew says:

    From Geoff Sharp: JPL Horizons Tells Us That Planet 9 Cannot Exist?
    Posted Mon, 08/05/2019

    JPL Horizons shows us that Planet 9 cannot exist.

    Back in 2016 there was a story on Planet 9 at Tallblokes blog where I questioned the viability of such a planet.

  6. oldbrew says:

    Sep 14, 2018
    This Is Why Most Scientists Think Planet Nine Doesn’t Exist
    – Ethan Siegel

    In short, we have to make sure that the evidence we’re seeing is representative of the objects that are out there, and that’s where this idea runs into trouble.
    – – –
    Re dark matter/dark energy – e=mc² (Einstein)

    Matter and energy are detectable, so how come they can’t find 95% of it? Major theory problem.

    And if they did find it, would there be 20 times too much matter/energy in the universe?
    – – –
    Mike McCulloch’s beginner’s guide – with a slide show – to his no-dark-matter theory: QI, or quantised inertia.

  7. rossa59 says:

    Unless it isn’t a planet but a dwarf star. Most stars that have been observed in the Galaxy, like our Sun, are binary star systems. It’s the most common set up. Often one smaller, orbiting the larger one at a great distance. May also explain the ‘wobble’ already observed that affects Pluto and the other outer planetary bodies. A gravitational pull by a dead Sun.

    Planet X, Nibiru etc., may have a seed of truth in them. There have been ancient cave paintings and friezes found in the Pyramids with twin stars in the sky. Either the people at the time were imagining things or at some time in the orbit of the second star it ‘appears’ in the sky. If Pluto orbits the Sun in hundreds of years, why not thousands of years for a twin star?

    Bearing in mind that at some point our yellow star will become a yellow white star. It will become bigger and will push the planets in our solar system further out, away from it. Would that be enough to push away a binary star or pull it in towards the Sun?

  8. tallbloke says:

  9. oldbrew says:

    rossa59 says: If Pluto orbits the Sun in hundreds of years, why not thousands of years for a twin star?

    Dwarf planet (1000 km. wide) Sedna has an orbit period of about 11,400 years.

  10. Geoff Sharp says:

    There is also evidence of a brown dwarf star passing through the outer reaches of the solar system about 90,000 years ago. The passing of this body (or any before) would also have a shepherding effect on any bodies it encountered.
    The major evidence against Planet 9 is the JPL Sun/SSB distances, yes these distances are calculated but they are also backed up by observations. These include occultations of asteroids and outer planets against the background stars.

  11. E.M.Smith says:

    There is also the point that precession may be due to a 2nd sun…

    The argue it is Sirius (and claim it doesn’t precess). Not sure I buy it, but interesting idea.

    Might that also explain the TNO orbits? Or is Sirius too far away or in the wrong direction?

    BTW: I agree with Richard Verney. Either “Planet Nine” isn’t a planet as it is a TNO and thus has not cleared its orbit, or that rule gets canned and then Pluto is back as Nine, and the new one is either Ten or an even bigger number as other known TNOs also become planets (some are bigger than Pluto…).

  12. p.g.sharrow says:

    @oldbrew; on quantising Inertia, I figured that out 25 years ago. It makes the Effects of mass/inertia external to Mater, Then many of the quirks on modern physics are explained, BUT it requires the acceptance Of the concept of Aether. As to “Dark Mater/Energy” they are both just words for the same phenomena, Aether! Quantaized Energy (negative charge). This also explains gravity as an energy field that behaves just like any other…pg

  13. oldbrew says:

    What if Planet 9 is a small black hole made just after the Big Bang?
    Sep 30 2019

    The idea that the feature influencing some of the most distant objects in the solar system could be the size of a bowling ball is being floated by two physicists in a paper published on the arXiv preprint server this week.

    – – –
    Shades of The Twilight Zone?

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