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Musings on Planet X

My younger son Alec can be forgiven a certain amount of confusion over the term ‘Planet X.’ Back in the 1980s, I told him all about the marvelous Edgar G. Ulmer film The Man from Planet X, a favorite since my own childhood. Ulmer was a gifted director who is rarely talked about today (see his 1945 film Detour for a glimpse of just how gifted). And 1951’s The Man from Planet X was compelling in a way that few B movies of the era achieved, with an alien whose spooky presence has stuck with me ever since I first saw him on an old black-and-white set.

A scene from The Man from Planet X

But then Alec encountered a different ‘Planet X’ in an astronomy class, learning that some astronomers had searched for a planet beyond Pluto, although at that point with notable lack of success. Planet X was supposed to account for various orbital oddities exhibited by Pluto and become emblematic of a fabulous, unknown place at the very edge of the system that was the ultimate catch for the next Clyde Tombaugh. I didn’t think it existed until Mike Brown came along.

Image: Actress Margaret Field approaches the alien vessel amidst a fine Scottish fog in Edgar G. Ulmer’s The Man from Planet X. Ulmer worked with the smallest of budgets but created suspense as much by what he didn’t show as what he did.

Brown, an astronomer at the California Institute of Technology, identified the world we’ve come to know as Eris, a place larger than Pluto and on an even more eccentric orbit well off the ecliptic. No wonder it took so long to find it. And just when we thought we had a real Planet X, my son was told that it wasn’t a planet at all. Oddly, finding an object larger than Pluto only reinforced the growing belief that Pluto itself was just one of many (perhaps hundreds, perhaps thousands) of large Kuiper Belt objects. The IAU made it official and now we have just eight planets.

The latest news about the demoted Planet X more or less makes the same point. New data from Brown and grad student Emily Schaller show that Eris is 27 percent more massive than Pluto. Says Brown:

“This was Pluto’s last chance to be the biggest thing found so far in the Kuiper belt. There was a possibility that Pluto and Eris were roughly the same size, but these new results show that it’s second place at best for Pluto.”

The data tell us that Eris is made up of ice and rock, thus similar to Pluto in composition. It’s bound to be a dark and lonely place, currently 97 AU from the Sun and sporting temperatures below -240 degrees Celsius. That orbit will eventually swing back around, highly elliptical as it is, to bring Eris within 38 AU, but right now it’s pretty much at aphelion, orbiting along with its moon Dysnomia in the outer dark. A fine, interesting object, but no longer fit to be declared a planet.

Sigh. The Man from Planet X has not, to my knowledge, made it onto DVD, but I managed to acquire, some ten years ago, a good videotape of it, and I was delighted to find that it has worn well over all the years. Sure, it’s schmaltzy and over-acted and it makes its points a little too heavily, but this is a B movie, remember? And the sets, the lighting, the fog over the Scottish moors where the odd glow of the alien craft can be seen at night, these are things that, to this day, put a chill up my spine.

Eris isn’t Planet X, but then we’re discovering plenty of worlds around other stars that should prove even more interesting. And as for the might-have-been Planet X, the new paper is Brown and Schaller, “The Mass of Dwarf Planet Eris,” Science Vol. 316, No. 5831 (June 15, 2007), p. 1585 (abstract available).

Comments on this entry are closed.

  • Tonyonyo June 14, 2007, 17:41

    The craft in the image looks kinda like ARCA’s Stabilo.

  • Administrator June 14, 2007, 18:00

    It does look a bit like the ARCA vehicle, doesn’t it? For those unfamiliar with ARCA, check this link:


  • Todd June 14, 2007, 21:41

    Both movies are available on DVD on Amazon.

  • Administrator June 15, 2007, 7:02

    Todd, thanks — hadn’t checked in a while. Time to replace my old videotape!

  • ljk December 3, 2007, 14:46

    Polarimetry of the dwarf planet (136199) Eris

    Authors: I. Belskaya, S. Bagnulo, K. Muinonen, M.A. Barucci, G.P. Tozzi, S. Fornasier, L. Kolokolova

    (Submitted on 30 Nov 2007)

    Abstract: We investigate the surface characteristics of the large dwarf planet (136199) Eris. With the FORS1 instrument of the ESO VLT, we have obtained Bessell broadband R linear polarimetry and broadband V and I photometry. We have modelled the observations in terms of the coherent-backscattering mechanism to constrain the surface properties of the object. Polarimetric observations of Eris show a small negative linear polarization without opposition surge in the phase angle range of 0.15-0.5 degrees. The photometric data allow us to suppose a brightness opposition peak at phase angles below 0.2-0.3 degrees. The data obtained suggest possible similarity to the polarimetric and photometric phase curves of Pluto. The measured absolute magnitude and broadband colors of Eris are H_V=-1.15, V-R=0.41, and V-I=0.75.

    Comments: Accepted by A&A

    Subjects: Astrophysics (astro-ph)

    Cite as: arXiv:0711.4974v1 [astro-ph]

    Submission history

    From: Stefano Bagnulo [view email]

    [v1] Fri, 30 Nov 2007 16:50:04 GMT (22kb,D)


  • ljk January 8, 2008, 9:25


    Professor of Planetary Astronomy Michael Brown is the subject of a
    recently published children’s book called “The Planet Hunter: The
    Story Behind What Happened to Pluto”. Written by Elizabeth Rusch and
    illustrated by Guy Francis, the book tells of Brown’s life from
    child- to adulthood and explains how his discoveries led to Pluto’s
    “demotion” from the status of planet to dwarf planet.

  • ljk January 13, 2008, 11:10

    The mystery of Planet X

    11 January 2008
    Govert Schilling
    Magazine issue 2638

    TWO years ago the solar system lost a planet. Pluto was deemed too insignificant to rank alongside Mars, Jupiter and the rest, and was demoted to dwarf planet status. Pluto’s fall from favour left us with only eight bona fide planets. But what the solar system has lost, Patryk Lykawka now hopes to replace.

    Lykawka, an astronomer at Kobe University in Japan, suspects a ninth planet as large as Earth is hiding beyond Pluto. So far, this frigid “super-Pluto” has escaped detection. But not for much longer, Lykawka hopes. “Within five years or so, we will know for sure if it exists.”

    Lykawka has become convinced of the existence of this planet thanks to a number of puzzling features in the Kuiper belt, a ring of icy debris in the outer solar system, of which Pluto is one of the largest members.


  • ljk February 29, 2008, 9:32

    Japanese scientists eye mysterious ‘Planet X’

    Kyoko Hasegawa , AFP
    Published: Thursday, February 28, 2008

    Scientists at a Japanese university said Thursday they believed another planet up to two-thirds the size of the Earth was orbiting in the far reaches of the solar system.

    The researchers at Kobe University in western Japan said calculations using computer simulations led them to conclude it was only a matter of time before the mysterious “Planet X” was found.

    “Because of the very cold temperature, its surface would be covered with ice, icy ammonia and methane,” Kobe University professor Tadashi Mukai, the lead researcher, told AFP.

    The study by Mukai and researcher Patryk Lykawka will be published in the April issue of the US-based Astronomical Journal.

    “The possibility is high that a yet unknown, planet-class celestial body, measuring 30 percent to 70 percent of the Earth’s mass, exists in the outer edges of the solar system,” said a summary of the research released by Kobe University.

    “If research is conducted on a wide scale, the planet is likely to be discovered in less than 10 years,” it said.

    Planet X — so called by scientists as it is yet unfound — would have an oblong elliptical solar orbit and circle the sun every thousand years, the team said, estimating its radius was 15 to 26 billion kilometres.

    The study comes two years after school textbooks had to be rewritten when Pluto was booted out of the list of planets.

    Pluto was discovered by the American astronomer Clyde Tombaugh in 1930 in the so-called Kuiper belt, a chain of icy debris in the outer reaches of the solar system.

    In 2006, nearly a decade after Tombaugh’s death, the International Astronomical Union ruled the celestial body was merely a dwarf planet in the cluttered Kuiper belt.

    The astronomers said Pluto’s oblong orbit overlapped with that of Neptune, excluding it from being a planet. It defined the solar system as consisting solely of the classical set of Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune.

    The team noted that more than 1,100 celestial bodies have been found in the outer reaches of the solar system since the mid-1990s.

    “But it would be the first time to discover a celestial body of this size, which is much larger than Pluto,” Mukai said.

    The researchers set up a theoretical model looking at how the remote area of the solar system would have evolved over the past four billion years.

    “In coming up with an explanation for the celestial bodies, we thought it would be most natural to assume the existence of a yet unknown planet,” Mukai said.

    “Based on our hypothesis, we calculated how debris moved over the past four billion years. The result matched the actual movement of the celestial bodies we can observe now,” he said.

    He was hopeful about research by Kobe University, the University of Hawaii and Taiwan’s National Central University.

    “We are expecting that the ongoing joint celestial observation project will eventually discover Planet X,” Mukai said.

  • ljk April 3, 2008, 11:16

    Eris – a dwarf planet

    March 29, 2008

    There are eight big things in the Solar System. These are the
    planets. There are lots of little things, including dwarf planets.

    Eris is a dwarf planet and lies three times further away than
    Pluto. It has a single moon, Dysnomia, who in Greek mythology
    is Eris’s daughter and the demon spirit of lawlessness.

    Full transcript here:


  • andy April 3, 2008, 13:12

    Eight big things? So which doesn’t count, the Sun or Mercury?

  • ljk May 27, 2008, 9:57

    No Planet X – and therefore no Doomsday – 2012:


  • ljk June 19, 2008, 17:09

    Large ‘Planet X’ May Lurk Beyond Pluto

    By Ker Than

    Special to SPACE.com

    Posted: 18 June 2008, 10:21 am ET


    An icy, unknown world might lurk in the distant reaches of our solar system beyond the orbit of Pluto, according to a new computer model.

    The hidden world — thought to be much bigger than Pluto based on the model — could explain unusual features of the Kuiper Belt, a region of space beyond Neptune littered with icy and rocky bodies. Its existence would satisfy the long-held hopes and hypotheses for a “Planet X” envisioned by scientists and sci-fi buffs alike.

    “Although the search for a distant planet in the solar system is old, it is far from over,” said study team member Patryk Lykawka of Kobe University in Japan.

    The model, created by Lykawka and Kobe University colleague Tadashi Mukai, is detailed in a recent issue of Astrophysical Journal.

    If the new world is confirmed, it would not be technically a planet. Under a controversial new definition adopted by the International Astronomical Union (IAU) last week, it would instead be the largest known “plutoid.”

    The Kuiper Belt contains many peculiar features that can’t be explained by standard solar system models. One is the highly irregular orbits of some of the belt’s members.

    The most famous is Sedna, a rocky object located three times farther from the sun than Pluto. Sedna takes 12,000 years to travel once around the Sun, and its orbit ranges from 80 to 100 astronomical units (AU). One AU is equal to the distance between the Earth and the Sun.

    According to the model, Sedna and other Kuiper Belt oddities could be explained by a world 30 to 70 percent as massive as Earth orbiting between 100 AU and 200 AU from the sun.

    At that distance, any water on the world’s surface would be completely frozen. However, it might support a subsurface ocean like those suspected to exist on the moons Titan and Enceladus, said Mark Sykes, director of the Planetary Science Institute in Arizona.

    “The interesting thing for me is the suggestion of the kinds of very interesting objects that may yet await discovery in the outer solar system,” said Sykes, who was not involved in the study. “We are still scratching the edges of that region of the solar system, and I expect many surprises await us with the future deeper surveys.”

  • ljk November 7, 2008, 0:05

    Digging Into the Surface of the Icy Dwarf Planet Eris

    Authors: M.R. Abernathy, S.C. Tegler, W.M. Grundy, J. Licandro, W. Romanishin, D. Cornelison, F. Vilas

    (Submitted on 5 Nov 2008)

    Abstract: We describe optical spectroscopic observations of the icy dwarf planet Eris with the 6.5 meter MMT telescope and the Red Channel Spectrograph. We report a correlation, that is at the edge of statistical significance, between blue shift and albedo at maximum absorption for five methane ice bands. We interpret the correlation as an increasing dilution of methane ice with another ice component, probably nitrogen, with increasing depth into the surface.

    We suggest a mechanism to explain the apparent increase in nitrogen with depth. Specifically, if we are seeing Eris 50 degrees from pole-on (Brown and Schaller, 2008), the pole we are seeing now at aphelion was in winter darkness at perihelion. Near perihelion, sublimation could have built up atmospheric pressure on the sunlit (summer) hemisphere sufficient to drive winds toward the dark (winter) hemisphere, where the winds would condense.

    Because nitrogen is more volatile and scarcer than methane, it sublimated from the sunlit hemisphere relatively early in the season, so the early summer atmosphere was nitrogen rich, and so was the ice deposited on the winter pole. Later in the season, much of the nitrogen was exhausted from the summer pole, but there was plenty of methane, which continued to sublimate. At this point, the atmosphere was more depleted in nitrogen, as was the ice freezing out on top of the earlier deposited nitrogen rich ice.

    Comments: This paper will appear in Icarus. It consists of 26 pages, 3 tables, and 5 figures

    Subjects: Astrophysics (astro-ph)

    Cite as: arXiv:0811.0825v1 [astro-ph]

    Submission history

    From: Stephen Tegler [view email]

    [v1] Wed, 5 Nov 2008 21:39:51 GMT (34kb)


  • ljk November 12, 2008, 8:02

    November 10, 2008

    Plutoid Eris is Changing… But We Don’t Know Why

    Written by Ian O’Neill

    Eris, the largest dwarf planet beyond Neptune, is currently at its furthest point in its orbit from the Sun (an aphelion of nearly 100 AU). At this distance Eris doesn’t receive very much sunlight and any heating of the Plutoid will be at a minimum.

    However, two recent observations of Eris have shown a rapid change in the surface composition of the body. Spectroscopic analysis suggests the concentration of frozen nitrogen has dramatically altered during the two years Eris had been at this furthest point from the Sun. This is very unexpected, there should be very little change in nitrogen concentration at this point in its 557 year orbit.

    So what is going on with this strange Plutoid? Is there a mystery mechanism affecting the surface conditions of this frozen moon? Could there be some cryovolcanic process erupting? Or is the explanation a little more mundane?

    “We’re really scratching our heads,” says Stephen Tegler of Northern Arizona University in Flagstaff, author of the new Eris research (to be published in the journal Icarus). Tegler and his team analysed spectroscopic data from the 6.5 metre MMT observatory in Arizona and compared their 2007 results with a similar observation campaign by the 4.2 metre William Herschel Telescope in Spain two years earlier in 2005.

    Full article here:


  • ljk November 5, 2009, 23:50

    Where Are You Hiding Planet X, Dr. Brown?

    by Ian O’Neill

    The scoop: Mike Brown is a professor of planetary astronomy at the California Institute of Technology (Caltech) and an expert dwarf planet hunter, accredited with discovering over 100 minor bodies in the Kuiper belt. Dr. Brown is also very well known for his part in the re-classification of Pluto.

    In this very special IM Interview, Dr. Brown takes some time out with space producer Ian O’Neill to discuss killing Pluto, hate mail and whether there’s a massive Planet X hiding near the Kuiper belt ready to strike Earth in 2012 (spoiler: Mike isn’t part of a global conspiracy to hide Nibiru). To keep up with his Kuiper belt adventures, follow Mike on Twitter: @plutokiller.

    Full interview here:


  • ljk December 28, 2011, 1:41

    Turner Classic Movies take on The Man from Planet X:


  • ljk November 5, 2012, 1:06

    Tom Swift, Jr., also had an encounter with a visitor from Planet X: