Mike Brown doesn't look like the type of man who would purposely destroy a planet; and in his defence, his act of celestial annihilation was an accident. However, people tend to be sentimental when it comes to worlds and, although astronomy professor Mike wiped Pluto out of the solar system four years ago, he still gets hate mail from ‘Pluto-huggers' today.
Ironically Brown was once described by Time Magazine as potentially "the most successful planet hunter in the history of the solar system". Today he is perhaps best known as the man responsible for demoting Pluto from its exalted planetary status to that of a lowly ‘dwarf planet'; which is a shame, as his work peering into the dark recesses of space continues to do much to further our understanding of our celestial neighbours. Just this last October, he reported to the international astronomy community the discovery that one of the bodies his team at the California Institute of Technology (Caltech) has been observing at the far reaches of our star system appears to have the remnants of an atmosphere.
Fiery controversy Pluto's undoing began when Brown embarked on a survey of the outer reaches of the solar system, in and beyond an area called the Kuiper Belt, which stretches past the orbit of Neptune and consists of ice and rock bodies preserved from the time of the Sun's creation.
His obsessive quest uncovered several large objects of which one, Eris, appeared bigger than Pluto. This presented the international astronomical community with a dilemma; was it a planet? If not, it would have to follow that neither was Pluto. The resulting debate about what constitutes a planet and the final decision to downgrade Pluto caused a firestorm of controversy, most of which was directed at Brown, who argued strongly against the case for Pluto and consequently undermined his own status as a space-age Christopher Columbus.
"I knew classing Eris as a planet was a very bad idea," explains Brown. "The word ‘planet' is not trivial; it should be reserved for the most important objects in our solar system. It would have been wrong to class Eris as a planet.
"There was a cartoon view of the solar system, like the one on my daughter's lunchbox, where Pluto is only a little bit smaller than the Earth and Jupiter is only a little bit larger than the Earth. In the view that a lot of people grew up with, Pluto is a prominent part of the solar system, but that is not the actual solar system.
"In the mid-1990s, researchers were discovering new objects in the outer solar system; objects that were small like Pluto, icy like Pluto, with elongated orbits like Pluto. It started me thinking that maybe Pluto wasn't the ninth planet. Maybe it was the first object of a new class of objects that populates this outer zone in the solar system."
There's a lot out there
When Brown, who has recently completed a lecture-tour of India, started his search for new objects in the depths of space in 1998, he hoped he might find the tenth planet (he defines planet-size as an object with the dimensions of Mars). However there was a deeper scientific reason for his survey.
"We were looking at the very outer edge of the solar system and that region has the best preserved parts of the solar system left. The objects out there haven't been squashed together, they haven't become hot, they can tell us so much about the earliest conditions in the solar system," he says.
Using cutting-edge technology such as robotic telescopes and automatic data reduction, Brown and his team at the Caltech began examining the entire sky for tiny specks of light millions of miles away, a task he likens to "meticulous book-keeping".
His efforts quickly paid off and, during stretches of clear visibility, the team discovered around one object each week. In June 2002 they made the first of several landmark discoveries. Quaroar, as it would later be named, was half the size of Pluto, had its own moon and was the first nail in Pluto's coffin. The second groundbreaking discovery was made in November 2004 and became known as Sedna, it remains one of the most important astronomical discoveries of recent times, being the first object discovered beyond the Kuiper Belt. It is currently located 90 times further from the sun than the Earth and is three times more remote than Pluto. It takes 12,000 years to orbit the sun and in 200 years will be too far away to observe. Explains Brown: "If we can find enough objects like Sedna we can reconstruct the earliest history of the birth of the sun; how and when it was formed, if there were other stars nearby and what their effect on the Sun was. Sedna is basically a fossil record of the birth of the Sun."
A difficult decision
Between December 2004 and March 2005 Brown found the other three largest objects in the Kuiper belt, and one of them, Eris (originally nicknamed Xena after the television female warrior), appeared bigger than Pluto. It gave the International Astronomical Union (IAU), mankind's arbiter of planetary order, a dilemma and the body convened in Prague in August 2006 to debate whether Eris and Brown's other discoveries were planets.
"Either they were going to declare me to be the discoverer of more planets than anyone else in human history or not. I felt like I had so much personally at stake that the best thing for me to do was stay as far away from it as possible," recalls Brown, who fled to a remote island off the North Western coast of the US and followed the debate online. However, when the IAU made an initial proposal to accept Eris as the tenth planet, Brown realised he had to act for the sake of accuracy, despite the consequences.
"I knew a decision to demote Pluto would cause a public outcry and the IAU knew demoting Pluto would incur public ire; everybody loves Pluto. They knew the most convenient thing to do would have been to keep things the way they were, but as someone deeply concerned with education and public understanding I couldn't sit by and watch that happen," says Brown. "I had always believed that it didn't make sense that Pluto was a planet and knew I would be getting hate mail from school kids if Pluto did get kicked out of the solar system."
Eventually, on August 25, 2006, a rebel faction of astronomers made a counter-proposal to place Eris and Pluto under a new classification; Dwarf Planet. Brown lobbied in support of this alternative view and the IAU reluctantly accepted it. The solar system was re-drawn and text books were revised.
For Brown, the pro-Pluto hate mail continues almost daily. He sighs: "I get obscene messages at 3am on my office line, which are really quite funny."
As for his feelings towards Pluto?
"It is like the child in the room who will not shut up," he laughs. "There are so many other fascinating things going on out there, maybe if we stopped talking about the planet debate and started talking about science instead, we would discover how interesting the edge of the solar system really is."
Prof Mike's astronomical events to look out for:
- June 2012 - partial lunar eclipse visible over Asia and Africa
- 2034 - solar eclipse over Dubai
How I killed Pluto and Why It Had It Coming by Mike Brown is available at www.amazon.co.uk
