Mike Brown has gotten a lot of hate mail over the years. His dissenters skew younger, their notes disproportionately crayon-scrawled. Brown, after all, will forever be known as the Man Who Killed Pluto, thanks to his 2005 discovery of Eris, an object more massive than the ex-planet that led astronomers to reconsider the definition of a planet. The solar system’s most charismatic planet was demoted, to the dismay of schoolchildren everywhere.
So when the Caltech professor was awoken this morning with a phone call at 4:30, he may have thought a particularly distraught 3rd grader was on the line. Fortunately, Brown received better news: He has been selected as a co-winner of the 2012 Kavli Prize in Astrophysics, a prestigious international award that comes with $1 million and an audience with King Harald of Norway.
Brown shares the award with Jane Luu of MIT and David Jewitt of UCLA. I caught Brown on his way to the airport to discuss his prizewinning work.
Wired: The Kavli Committee cites several discoveries as evidence of your fundamental contributions to the field of astrophysics. One of them is Sedna; why is this particular object important?
Brown: Sedna might be my favorite object we’ve come across. It goes around the sun in a looping orbit every 12,000 years, but its orbit is completely unconnected to anything else in the planetary system. For every other object, you can explain where it is and why it’s there based on gravitational interactions with giant planets or with other orbiting objects. Everything else makes sense. Sedna, on the other hand, is far enough away from the planets that nothing ever interacts with it now, but something had to have kicked it into this strange orbit.
This means that there was something else here in the Solar System to make that orbit happen -- maybe a leftover fossil signature from when the Sun was born. If the Sun was born in a cluster of stars, for example, some of those other masses could have influenced Sedna’s orbit and left an imprint that we still see today. To me, Sedna is a reminder that there are still a lot of basic questions about the formation of our Solar System that aren’t known.
Wired: You’ve spent years surveying large sections of the sky with no guarantee that anything interesting would come of it. When did you first sense that this was a big deal?
Brown: It built slowly actually. In 1998, we started a search across the sky for large undetected objects that might tell us more about how the Solar System formed. We found things in an interesting order -- at first we found relatively small objects, and as we kept searching we found bigger and bigger objects. It turns out that the largest objects in the outer solar system are away from the plane of the planets, away from the ecliptic. We had no idea, so we first searched in that plane. It seemed that if the planets were all in one plane because of the Solar System’s rotation, other large objects would be too.
Then we thought we might as well search off the ecliptic and we found slightly larger objects; only when we got quite far off the ecliptic did we find the biggest things. No one thought this would be the case. So there as never really one moment, just this growing urgency and the sense that things in the Solar System weren’t always the way we understand them today.
Wired: What are the biggest questions these days in astronomy?
Brown: There are all kinds of important questions in astronomy -- from big cosmic-scale questions about dark energy to questions of planet formation and habitability. Astronomy is so diverse that I certainly can’t speak for the field as a whole, but in my field, I’m most excited about trying to understand the fossil record of Sedna, trying to reconstruct the earliest history of the Sun and get back to the moment when the Sun and the planets were born. That’s the most exciting thing to me.
Wired: The Kavli Astrophysics Prize, which was split three ways, comes with $1 million. What will you do with your share?
Brown: They woke me up at 4:30 in the morning with a phone call and told me the news, so I haven’t had much time to think about it. My wife says college tuition for the kids.
