Friday, September 15, 2006

And then there were eight...

cover story

Poor Pluto had always been the odd one out – it was just too little, too far away, and unfortunate enough to share its name with a Disney cartoon character. Still, we’d embraced it as one of our own, accepting it as a member of the planetary family despite its small size and eccentric orbit. But the evil scientist people had other plans, and after more than seven decades of being listed as a planet, little Pluto was demoted to the position of (gasp!) a dwarf planet. Now, textbooks will need revision. Star charts and universe displays will need adjustment. And pro-Pluto groups might have to resort to therapy. All this because of a few hundred guys and their rather silly decision.


“Personally, I don't think there's intelligent life on other planets. Why should other planets be any different from this one?” - Bob Monkhouse

Astronomy, the study of celestial objects, is one of the oldest sciences, and continues to fascinate humankind for many reasons: it helps us in understanding mysteries like the nature of the universe and its contents; it attempts to find the answers to queries, like the existence of intelligent life elsewhere in the universe; it is one of the few sciences where amateurs can play an active role, especially in areas of discovery and observation; it opens the door to an intriguing world, showing us where we stand in the grand scheme of things; and, most importantly, it gives rich countries an excuse for wasting billions of dollars. The science has come a long way from its naked-eye observation and prediction days, and scientific advances have led to more data about the universe, primarily focusing on our cosmic neighbourhood.


“After one look at this planet any visitor from outer space would say, ‘I want to see the manager’.”- William S. Burroughs

Comprising of planets, moons, dwarf planets, asteroids, meteoroids, comets, interplanetary dust, and the star known as the Sun, the Solar System can be defined as the portion of the universe under the gravitational influence of the Sun, which might be just an ordinary star with respect to the rest of the universe, but to our Earth, this fiery ball of hot gas helps to support almost all life on the planet, while serving as a brand name for everything from newspapers and tabloids to TV channels and cable services, and providing a source of income to the nice folks who make sunscreen.

For centuries, planets (planet: Greek word for ‘wanderer’) were simply objects that moved in the sky with respect to the background of fixed stars, and for decades, just as sure as we were of the facts that there are twenty-four hours in a day, twelve signs of the zodiac, and seven dwarfs who gave refuge to Snow White, we’d known that our Solar System was home to nine planets.

- Nine

“Not only do we not understand the universe, if someone explained it to us, we wouldn't know what he was talking about.” - Isaac Asimov

Since the discovery of Pluto in 1930 by Clyde Tombaugh, the Solar System was considered to have nine planets, typically subdivided into the inner terrestrial planets (Mercury, Venus, Earth, and Mars), and the outer gas giants (Jupiter, Saturn, Uranus, Neptune, and Pluto). While some planets were discovered by sightings and telescopes, others were discovered as a result of calculations rather than observations, and since the start of the space age, a great deal of exploration has been performed by unmanned space missions and landings. It was the calculations, however, that would give science fiction writers something to harp on about.

- Ten

“Imagination will often carry us to worlds that never were. But without it we go nowhere.” - Carl Sagan

For all anyone knew, the tenth planet, a.k.a. Planet X, a.k.a. Persephone, a.k.a. Proserpina, a.k.a. (insert whatever name you want here), might have been nothing more than a figment of our collective imagination, but it sure added some zing to those otherwise zing-less astronomy lessons. From measurements to myths, astronomers and the general public alike had speculated the existence of a tenth planet for many decades. Believed to be a fifth gas giant beyond the orbit of Neptune according to a hypothesis first put forth in the late 19th century, Planet X was intended to explain perceived anomalies in the orbits of the outer planets, especially those of Uranus and Neptune. But the discrepancies were largely resolved by more accurate calculations and caused the anomalies to vanish without the need for an extra planet, hence ending any chances for the success of the ‘Planet X for planetary presidency’ campaign. (The said campaign, however, was bound to fail anyway, as it never really existed in the first place.)

The discovery of the Kuiper belt, which is a vast population of icy objects that orbit the Sun beyond Neptune, led the nerdy types that make up the astronomical community to speculate that some other Pluto-like object might be awarded the tenth planet title. But the astronomers needed to do something else first: agree on a scientific definition of the word ‘planet’, and that’s what started the chain of not-so-eventful events that let to little Pluto getting kicked off the planet list.

- Twelve

“There is a theory which states that if ever anyone discovers exactly what the Universe is for and why it is here, it will instantly disappear and be replaced by something even more bizarre and inexplicable. There is another theory which states that this has already happened.” - Douglas Adams

In recent years, the discovery of new bodies, which are comparable to Pluto in terms of size and orbit, led to a situation where “either the minor bodies would be added to the list of officially recognized planets, or older ones would need to be removed in order to ensure consistency”. The need to categorize and name the recently-discovered bodies, and probably because the members of the International Astronomical Union (IAU) had run out of things to argue over, ultimately resulted in proposals to redefine the term ‘planet’.

The IAU met in August 2006 in Prague, and initially proposed a definition according to which any body that had “sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium shape, and is in orbit around a star, and is neither a star nor a satellite of a planet” was to be considered as a planet. This definition would have led to the number of planets going up to twelve with the inclusion of three celestial bodies: Ceres, Charon, and 2003 UB313. The more the merrier, you’d think, but the proposed redefinition was criticized as ambiguous and did not make the final cut, and a further revision of the definition resulted in the number of planets being cut down to eight.

- Eight

“I would rather be a superb meteor, every atom of me in magnificent glow, than a sleepy and permanent planet.” - Jack London

The final definition, as passed by the IAU on the 24th of August read:
“The IAU...resolves that planets and other bodies in our Solar System be defined into three distinct categories in the following way:
(1) A "planet" is a celestial body that:
(a) is in orbit around the Sun,
(b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, and
(c) has cleared the neighbourhood around its orbit.
(2) A "dwarf planet" is a celestial body that:
(a) is in orbit around the Sun,
(b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape,
(c) has not cleared the neighbourhood around its orbit, and
(d) is not a satellite.
(3) All other objects except satellites orbiting the Sun shall be referred to collectively as "Small Solar System Bodies".”

Pluto fails to meet the third condition (1c) – its highly elliptical orbit overlaps with that of Neptune – thus concluding it’s reign as a planet and ending up in the dwarf planet category. The pro-Pluto folks, however, say that no planet ever fully clears its orbit. What did poor Pluto ever do to those IAU people? And is it not our responsibility to stand up for those who are smaller and weaker than us, etc. etc.? Although, to be fair to the IAU committee, debates on the whole “clearing its orbit” issue have since clarified that the term refers to the “process that happened during the formation of the planets, and does not talk about the presence of bodies that later strayed into the orbit after the accretions took place.” Oh well.


“We do not have to visit a madhouse to find disordered minds; our planet is the mental institution of the universe.” - Johann Wolfgang Von Goethe

So Pluto was voted off. The IAU had spoken. But the announcement resulted in a considerable amount of bickering and astronomer backlash. Many astronomers had been unable to make the trip to Prague and, thus, cast a vote, and the orchestration of the final vote came under criticism within hours of the announcement because of the lack of participation from conference participants. Apparently, the final vote was taken on the last day of the 10-day conference, after many participants had left or were preparing to leave; of over 2,700 astronomers who attended the conference, only 424 remained on the last day. Why everyone had been in such a hurry to leave, I’ll never understand.

Only a week after the conference, astronomers who were dissatisfied with the new definition and the resulting Pluto demotion, launched a campaign to have the decision reversed. Currently, many petitions exist online asking the IAU for reinstatement, and it remains to be seen whether anything will come about as a result of the protests by Pluto well-wishers.


“The dinosaurs became extinct because they didn't have a space program. And if we become extinct because we don't have a space program, it'll serve us right!” - Larry Niven, quoted by Arthur Clarke

How fair is it to tell a planet 76 years after it's been discovered that ‘hey, we’ve changed our minds, we aren’t called a planet anymore’? The decision to strip Pluto of it’s planet title has raised quite a few issues about humankind’s prejudices and discriminations, and has led to efforts to protect the little ones from insults hurled against them by the inhabitants of a somewhat larger lump of rock.

And the rights of small cold gaseous planets aren’t the only cause for concern here. Up until a few weeks ago, Clyde Tombaugh’s ashes (which are being carried on the New Horizons spacecraft) were traveling towards a planet. The ashes are now heading towards a dwarf planet. I guess it would be safe to assume that he won’t be too pleased about this.

Other than that, you will have, by now, realized that distant planet-like-bodies don’t make for particularly interesting dinning-table conversation. And whether we like the decisions or not, it looks like we will all have to put up with “if it looks like a planet and orbits like a planet and has moons like a planet, then it must be a duck” jokes for quite some time to come.

- By Sameen Amer

Us Magazine, The News - 15th September, 2006