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.





Summer Hits: Martian Water, Asteroid Nukes, Orbital Antimatter!

1 10 2011

Here’s a recap of some of this summer’s greatest hits in space news that you might have missed:

Water on Mars

Dark streaks as summer flow features in Newton Crater, Mars. (Credit: NASA)

In an utterly tantalizing development, scientists analyzing imagery from the Mars Reconnaissance Orbiter (MRO) have announced what appears for all the world to be direct evidence of water on Mars!

Because the MRO has been orbiting the Red Planet since 2006, it has been able to view the same portions of the world at different times of year with an eye toward spotting any potential seasonal changes.  This past August, the MRO team reviewing this growing dataset hit paydirt.

Specifically, the team identified dark streaks on the slopes of steep terrain in the southern hemisphere that are found during Martian spring and summer; these features disappear during Martian winter only to return once again the following spring.

While there are multiple possible explanations, the most likely amongst them appears to be the flow of briny (salty) groundwater that warms in the hotter months, breaches the surface, and evaporates/sublimates as it flows downhill.

Time will tell on this one, but all eyes should be on the possibility of subsurface briny Martian aquifers!

Russian “Armageddon”

Asteroid impact as depicted in the film "Deep Impact." (Credit: Paramount/Dreamworks)

This past August, Russian scientists took a note from Hollywood and seriously proposed the use of nuclear weapons as a means of asteroid mitigation.

Under the scenario, a dual-spacecraft architecture would be employed, with one spacecraft, called “Trap,” ferrying a nuclear warhead to the target while a second spacecraft, “Kaissa,” (apparently and intriguingly named after the mythical goddess of chess,) analyzes the target asteroid’s composition to determine the appropriate warhead use scenario (deflection vs. break-up).

The spacecraft would be lofted by a Soyuz-2 rocket and/or Russia’s upcoming Rus-M rocket.

While much contemporary research casts doubt on the ultimate effectiveness of a nuclear detonation in such a context, the proposers stressed that the technique would only be used on approaching objects up to 600 yards in diameter.

Orbital Antimatter Belt

Antiprotons trapped in the Earth's magnetic field (in pink). (Credit: Aaron Kaase/NASA/Goddard)

Also this past August, researchers published a stunning (but in retrospect, sensible) discovery in Astrophysical Journal Letters: Earth possess a natural orbiting belt of concentrated antiprotons.

Succinctly, the interactions of high-energy cosmic radiation with the Earth’s atmosphere can produce infinitesimal and ordinarily short-lived bursts of antimatter.  These antiparticles normally react with standard matter present around the Earth and annihilate.

However, in the near-vacuum of space beyond the bulk of the Earth’s atmosphere, some of these antimatter particles are spared immediate destruction.  Many of these antiprotons are then herded by the Earth’s magnetic field into bands or belts, which were recently discovered by the antimatter-hunting satellite PAMELA.

Aside from the “gee-whiz” factor, there are certain technical and economic reasons to get excited about the finding.  For starters, the energy density of antiprotons is on the order of a billion times greater than conventional chemical batteries.  However, at a current production cost on Earth of nearly $63 trillion per gram, antiprotons are a bit hard to come by and even less practical to use for anything other than research; Identifying a natural reservoir such as, say, a naturally-produced orbiting belt could open up additional avenues of use for antimatter as well as be immensely lucrative… if only one could solve the lightning-in-a-bottle problem of antimatter storage.

In any case, this is definitely something to keep an eye on.  For the less techno-jargon-inclined, news reports on the find may be found from the BBC as well as Science Magazine.








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