Pluto’s Pain: The Unsung Story of Ceres

20 07 2012

Pluto is once again in the press, astronomers having recently discovered a fifth moon about the tiny, icy world.  -And, again, Pluto’s official designation as a “dwarf planet” is coming under fire.

However, Pluto’s pain really hearkens back to a much older story – one of an unsung planet that stood proudly in the rightful lineup alongside Earth, Venus, Mars, and the rest of the household-name kin of the Solar System for nearly a half-century, yet today nearly no one knows its name:

This is the oft-overlooked story of the scrappy planet Ceres [planet symbol:], which ultimately becomes the story of Pluto.

A Persistent Pattern

The story begins in the late 1700s, when the maturing discipline of astronomy discovered what was believed to be a pattern in the orbital semi-major axes (read: distances between) the planets.  The Cliff’s Notes version of the orbital mechanics here is that there appeared to be a gap between Mars and Jupiter where another planet should have been.

Thus at the turn of the 19th Century began a concerted effort to find this missing world, bringing to bear a contingent of respected astronomers and an arsenal of the most advanced telescopes the science of the time had to offer.

It wasn’t long before they hit paydirt.

(In an ironic turn, I should note that the subsequent discovery was made despite the fact that the ultimate logic of this proposition – the Titius-Bode Law – turned out to be wrong!)

 A Group Effort

In an unbelievable stroke of serendipity, one of the astronomers selected for the search won the race before he’d even entered.  Before Giuseppe Piazzi at the Academy of Palermo, Sicily had even been approached to join the strike team of planet-hunters, he pegged what would turn out to be Ceres while making separate astronomical observations on New Year’s Day, 1801.

A flurry of activity followed during the next year, with the observations changing hands multiple times before a young mathematician named Carl Friedrich Gauss (of differential geometry and magnetism fame), only 24 at the time, predicted the small world’s position to within a half-degree.

Gauss’s calculations led astronomers to the definitive discovery on December 31, 1801, nearly a year to the day of Piazzi’s initial discovery.

The Rise and Fall of Ceres

The discovery of a new world made waves through the astronomical community, with Piazzi naming the planet after the Roman goddess of agriculture, Ceres.  (The names Hera and Demeter have also been bounced about in different cultures, but the current generally-accepted name is Ceres.)

With a diameter of just over 600 miles, (almost exactly the same size of the peninsula of Korea), the world is something of a planetary runt.  However, this did not stop the planet from being included in astronomy textbooks as a brother amongst the rest of the known planets for more than a half-century.  Unlike the asteroids with which it was eventually found to share its orbit, Ceres is a true differentiated astronomical body that has reached so-called hydrostatic equilibrium, becoming a spherical world.

It was only as telescope technology improved and astronomy advanced that the understanding of what Ceres was began to change.  A sudden flood of asteroid discoveries at roughly the same orbital distance began to cast doubt upon Ceres’s uniqueness in the solar system.  Eventually, it was realized that all of these many new, small bodies would either have to also be called planets in order to remain consistent, or the definition of Ceres would have to be changed.

And so, unceremoniously, Ceres was demoted to the ringleader of the asteroids in the latter half of the 19th Century.  This means that by the time our grandparents came on-scene, one would have been hard-pressed to find a modern book that included more than a passing reference to this once-celebrated world.  It had become merely an asteroid.

The 2006 Upheaval

More than a century passed after the discovery of Ceres, and in the 20th Century a familiar story then began to unfold:  Pluto, which was determined to be a tiny world beyond the orbit of Uranus, was discovered in 1930.  It was added to textbooks as the ninth planet, as many of us grew up with.  However, during the 20th and early 21st Centuries, a flood of discoveries of other small, icy bodies in the outer solar system began to cast doubt upon Pluto’s uniqueness.  All of these objects together made up what became known as the Kuiper Belt, a zone of remnant material left over from our star system’s formation and the reservoir from which comets are occasionally pulled.

So, everyone knows that the reclassification of what makes a “planet” resulted in Pluto’s demotion to a new class of worlds called “dwarf planets.”  What few realized, however, was that Pluto’s loss was another’s vindication!

Ceres – waiting patiently in the wings for nearly 150 years – was promoted as a result of the change.  Instead of being “just” an asteroid, it too became a dwarf planet alongside Pluto.  Each as a result of the change evolved into small but noteworthy masters of their respective belts of material – Ceres the dwarf planet of the asteroid belt, Pluto the dwarf planet of the Kuiper belt.

In a way, the controversy resulted in long-awaited justice for little Ceres.

Take-Away

Perhaps, when engaged in your own debate about whether or not Pluto should be called a planet, you might decide to frame the conversation in a larger context.

It really isn’t just about Pluto.  Remember Ceres.

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Solar System has more than one “Planet X”?

12 06 2010

Recent observations of the nearby (44 light-years away) multi-planet star system Upsilon Andromedae have kindled in my mind an intriguing question:  Namely, can our own solar system have one or perhaps many “Planet Xs” hiding in oblique orbits?  Allow me to explain.

New findings show Upsilon Andromedae's planets have oblique orbits. Credit: NASA, ESA, A. Field

It has been known for quite some time that the Upsilon Andromedae star system is composed of at least three Jupiter-sized planets (we can’t yet see Earth-sized planets or smaller, yet).  However, research recently presented at the American Astronomical Society suggests that unlike our solar system where the major planets orbit in the same plane, two of Upsilon Andromedae’s three known planets orbit askew with respect to each other to the tune of nearly 30 degrees tilt.  This defies what we have come to know as a “normal” star system configuration of planets.

While there have been many “Planet X” hypotheses in our own star system over the years, including recent research suggesting the possibility of a large, distant icy planet in our own solar system, (see Tyche post here,) astronomers have not yet been able to locate any of these proposed culprits of periodic extinctions or comet peculiarities.

However, planets are notoriously difficult to find, especially the farther away from the Sun they are.  Planets do not intrinsically emit their own light (except infrared), and their reflections get exponentially dimmer with distance.  So, with the recent Upsilon Andromedae findings in mind, perhaps the reason we’ve yet to find any Planet Xs isn’t because there’s no merit to the ideas, but rather that astronomers have been looking in the wrong orbital planes.

Let’s investigate a step further. With “ordinary” planet formation in a young star system, the conservation of angular momentum causes material around a new sun to flatten into a disk, (called a “proplyd” or protoplanetary disk,) and planets form from the material in this disk.  Hence, planets will be found in an orbital plane around a star, just like ours are.  However, when we look closely, we find that there are even notable oddities in our solar system.  Namely, Uranus is tilted almost completely 90-degrees onto its side, and Pluto is not only tilted sideways, but it also orbits obliquely, much like its Jupiter-sized kin in Upsilon Andromedae.  What does this mean?  At the very least, it means that the evolution of any star system is a dynamic process.  At most, this is an indicator that we’ve yet to fully describe our own system.

On this note, Upsilon Andromedae is actually a “quiet” binary star system.  The main star, Upsilon Andromedae A, is a yellow-white star not unfamiliar to human eyes.  However, it does have a dim, red dwarf brother (unsurprisingly called Upsilon Andromedae B) in a wide orbit, far enough away to leave the planets orbiting Upsilon Andromedae A alone, so far as we are able to tell.  However – it does beg the question: Might subtler interactions of Andromedae’s red dwarf or perhaps outer, dimmer planets we have yet to find be responsible for the oblique orbits we see?  And if so, have we found a distant mirror suggesting there might be more places to look for Planet X in the far reaches of our own system?

Food for thought.





Give it a rest, people: Voyager 2 spacecraft not hijacked by aliens

13 05 2010

NASA is having a hard time talking to the Voyager 2 probe.  It started in late April and has only gotten worse, with the latest transmission being quite garbled.  Now, I can understand a bit of fun, tounge-in-cheek speculation, but this “Aliens have hijacked Voyager 2!” thing has gotten way out of hand.  It’s as though someone has been subliminally beaming the plot of Star Trek: The Motion Picture into everyone’s minds…

Voyager 6 spacecraft after being hijacked by aliens as seen in Star Trek: The Motion Picture. Credit: Paramount

…and for the unwashed, the movie centers around a mysterious cloud of energy headed for Earth destroying everything in its path.  It is revealed in the final act of the film that the cloud is actually the probe Voyager 6, which according to future history was lost, and Kirk and crew learn that it was hijacked, reprogrammed, and empowered by aliens before being sent back.  Sound familiar?

No one (or should I say, nothing?) has “done” anything to the blasted spacecraft, people.  It’s getting old.  How many other 30-year-old computers do you know of that are still running perfectly? 

Yes, Hartwig Hausdorf (who first made the alien hijacking crack) is allowed his opinion.  Is it realistic?  Nope.  Let’s just hope this probe can be recovered… It’d be a pity to lose one of only two “eyes” we have moving out of the solar system for the first time.

Sheesh, I just wish real science got this much press.





Solar System’s “Planet X” Returns!

30 04 2010

Researchers propose new planet "Tyche" on distant fringe of solar system. Inner planets on this diagram are too close to the Sun to see. (Credit: Ben McGee)

Our solar system may have just gotten a lot more interesting. Researchers studying the orbits of comets at the University of Louisiana have found a problem.  -They’ve discovered an inconsistency with how comets are spread out compared to what you would expect under ordinary galactic conditions.  In an article recently submitted to the journal Icarus, they propose the existence of another behemoth planet orbiting far beyond Pluto along the outskirts of the Oort Cloud (a huge sphere of proto-comets  that surrounds the solar system) and that this proposed planet, Tyche, is responsible for what they see.

This calls to mind another similar hypothesis based on the apparently cyclical nature of mass extinctions throughout Earth’s history and on geologic evidence from the Moon.  Called the Nemesis theory, it proposes that our solar system is actually a binary star system, and that the Sun’s twin is a small, dim, red dwarf star named Nemesis orbiting far beyond the Oort cloud.  As the theory goes, Nemesis passes close enough to the Oort cloud to send a deadly rain of comets into the inner solar system every few-score-million years or so.  The name here is completely appropriate, as those familiar with Greek Mythology will recall that Nemesis is the goddess of Retribution.

While the Tyche and Nemesis models are clearly different proposals, the researchers offering the new proposal are aware of the similarities.  According to Greek Mythology, Tyche is Nemesis’s good sister, the goddess of Fortune and Luck.  Say what you will about the penchant of astronomers to lean on mythology – I think it’s clever.

With all of these findings hinting at something going on in the outer solar system, it seems as though there’s something there to find.  A cold gas giant would be fascinating, as would the revelation that our Sun has had a twin all along.

Maybe even both.








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