Mike Brown's Planets

My preview of the reviews for The Pluto Files: The Rise and Fall of America's Favorite Planet by Neil DeGrasse Tyson and The Hunt for Planet X: New Worlds and the Fate of Pluto by Govert Schillng is in the September issue of Physics Today.

Or you can read it here.

Forty years is a long time, particularly if you are only a smidge over forty yourself, like me. When I was a kid, I wanted nothing more than to be an astronaut and go to the moon like those guys did 40 years ago today. The father of everyone I knew – mine included – was some sort of engineer working to build the Saturn rockets to send men to the moon (for a while as I child I thought that when you grew up you became a rocket engineer if you were a boy and you married a rocket engineer if you were a girl; few other options in the world appeared to exist). When Neil Armstrong stepped on the moon, I was pretty sure that that was exactly what I was going to eventually be doing, too. I drew picture story books of rockets and command capsules and lunar modules and splash down. I made cardboard models of Lunar Rovers and designed outposts where, I was pretty sure, I would eventually live.

The moon landings have faded into history as simply one of those amazing things that happened a long time ago that we don’t do any more, like dog treks to the south pole, first ascents of unscouted peaks, and world wars.

Every once in a while, though, something happens that pulls the moon landings out of the abstract haze of history and makes me remember: these things were real! They really happened. Here are two:

A few years ago I was giving a talk in New York City at the Hayden Planetarium, and I decided to spend the afternoon visiting the Planetarium itself and the Museum of Natural History. I was particularly interested to see how they were dealing with all of the controversy over Pluto, the then-embattled 9^th planet. And I was mesmerized by the best example I had ever seen of a Pallasite meteorite – a chunk from the boundary between the inner iron core and the rocky mantle of a little dwarf planet in the asteroid belt which got smashed to little bits, one of which I was staring at. But the part of the visit that unexpectedly took my breath away was staring at the pictures that were strewn on the walls of the hallways of the Planetarium with little fanfare. These were full sized prints of pictures taken by the Apollo astronauts, prints so large that you could stick your face right up to them and see details that you would never seen in the typical book or TV show or anything else. And most of them I had never seen before, anyway. There are only a few canonical moon shoots that we have all seen over and over and over but most of the hundreds and hundreds of pictures have not gotten much light of day. And oh what pictures. Standing and staring at those pictures took me back 35 years to when I wanted to be an astronaut. They were really there. You could almost taste the moon dust.

My favorite of all of the pictures, and the one that made me suddenly re-remember how spectacularly far-fetched the whole idea of going to the moon was, was a shot where you could see the lunar rover in the near foreground and way way way way way in the distance was the lander. And suddenly I realized: these two men are so far removed from home that the chance they will ever make it back alive seems miniscule. They are hundreds of yards from the rover, which is miles from the lander, which has to take off from the surface of the moon, rendezvous with the command module, return to the earth, drop out of the sky, and splash down into the ocean. And it all has to work. What were they thinking?

I stumbled across one of my other favorite Apollo moments a few years ago through some sort of random web surfing, looking for I-can’t-remember-what. My eye was grabbed by a link to an annotated transcript of the Apollo 11 landing. I clicked and started reading. I looked up 30 minutes later in a sweat, my heart pounding, and, again, thinking: who possibly thought that this would work? These guys were insane. I was too young at the time of the Apollo 11 landing to have known at the time whether or not people paid attention to how close Apollo 11 came to not making it. And how nail-bitingly suspenseful to know if they were going to land or crash or abort or something else entirely. I won’t give away the ending (perhaps you know it already), but instead simply point you in the right direction. I can read the whole thing over and over again (and pause for all of the audio clips and film clips), but if you feel the need to cut to the chase, start at 102_48_08 with “Eagle, Houston. You’re Go for landing. Over.”

I just did it again. To get the link right here I searched for the page again and while I was at it I read the whole thing. And my heart rate is still going strong.

Just in time for the big anniversary there are a slew of new books about the moon, of course. I recently got two of them to whet my lunar appetite. They both have that ability to make me re-remember my astronaut-yearning days, but each in very different ways.

Who could not like the idea of Moon 3-D: The Lunar Surface Comes to Life? As long as you can get over reading the book while looking through built-in 3D glasses (and thus looking pretty silly to anyone around you, including even 4 year olds), the book is a pleasure to look through. I never realized that the astronauts purposefully tried to take 3D image. They didn’t have any of the bulky dual camera stereoscopic equipment that people usually use, they simply took a picture and then moved left or right a few feet and took another. The results range from hard-to-figure-out to spectacular. And the 3D really works most of the time (enough so that after the 4 year old was finished making fun of me for the funny glasses she wanted to look through them herself and she made ooohing and ahhhhin sounds and kept taking off the glasses to make sure nothing funny was happening). A personal favorite of mine is an Apollo 15 picture looking back at the lander with desolate mountains in the background and footprints all around the base. Even with 3D none of the pictures quite has the impact of the large prints on the wall of the Hayden Planetarium, but if you’re not headed into New York anytime soon, this might be the way to relive the moon.

The other book takes a special type of space geek to enjoy. Missions to the Moon, a big glossy book chock full of geeky things like reproductions of Wernher Von Braun’s design for a space station, somebody’s schematic sketch of how an Apollo mission would work, a schematic of the Apollo console with all of the lights and switches indicated, and, my favorite, the lunar module descent monitoring chart, which the astronauts would have used to look out the window and know they were going in the right direction. Couple that with the transcript of the landing itself and see if you can follow the whole thing.

After Lilah got done playing with the 3D glasses she, of course, wanted to know what all of those other things in the other book were, and I explained all about landing on the moon to her. Today, on our drive in to school, we listened to Buzz Aldrin on the radio, and I told her, again, that he was an astronaut who went to the moon.

“Why is everyone talking about the moon today, Daddy?”

And I explained about how on this day, 40 years ago, astronauts landed on the moon.

Forty years is a long and arbitrary time in some ways, but to me, and to Lilah, this was even more meaningful. I am 40 years and 1 month older than my daughter. I remember when Armstrong and Aldrin stepped on the moon 40 years ago today; the things I saw and the things I read and talked about affected the direction of the entire rest of my life. Lilah is, finally, the same age as I was then. What will she remember? Where will she go? No way to know, but I’d like to ask her in 40 years if she remembers a day we looked at books and listened to the radio and tried to remember what it was like 40 years before that when I was a 4 year old watching people on the moon for the first time.

I was asked by a magazine to review Alan Boss's new book The Crowded Universe. They asked for a review that was a much an essay on the field as a review of the book itself, which made it a very fun exercise. The following is based on the review that I got to write.

Two hundred fifty years ago, Immanuel Kant, in his Universal Natural History and Theory of the Heavens, laid out a remarkably modern-sounding account of the state of the universe. Moons go around planets. Planets go around stars. Stars go around the Milky Way. The Milky Way and other galaxies (“other Milky Ways,” he called them) go around something even larger. The solar system had an understandable origin, and inevitable consequences:

The planetary structure in which the sun at the centre makes the spheres found in its system orbit in eternal circles by means of its powerful force of attraction is entirely developed, as we have seen, from the originally distributed basic stuff of all planetary material. All the fixed stars which the eye discovers in the high recesses of the heavens and which appear to display a kind of extravagance are suns and central points of similar systems.

To paraphrase: gravity takes stuff and turns it into stars surrounded by planets, and it has done so everywhere you see a star in the sky.

For the first 240 years after the publication of Kant’s assertion, this fact could only be verified for only a single star in the sky: the sun. In 1995 Michel Mayor and Didier Queloz announced the discovery of the first planet orbiting a star other than the sun. Now, fourteen years later, almost 300 stars are known to have planets around them. It is not quite “all of the fixed stars which the eye discovers,” but it’s getting close. Kant was substantially correct. It had been accepted since the 17^th century that our sun is not special, but is, instead, but one of many stars in the universe. Now, at the beginning of the 21^st century, it is clear that our planets aren’t special either.

Except that some of our planets are still special.

It is tempting to describe the many planetary systems that have been discovered in the past decade and a half as simply weird. Rather than the orderly arrangement of planets that we have here in the solar system, with small planets close, large planets far, and everything going around the sun in satisfyingly circular orbits in a common disk (each one of these properties is “inevitable”, according to Kant, and according to most astronomers up until late 1995), we have instead found planets the size of Jupiter that orbit their stars closer than Mercury, planets with orbits as elliptical as some of the comets in the solar system, and planets with separations from their central star far beyond even the most distant objects detected in our solar system. Weird, indeed. The only type of planetary system that we haven’t found, it seems, is one like our own. Nowhere out there has there been anything quite like the solar system; nowhere out there is another Earth.

But even this special position that our home planet holds is now in jeopardy.

Alan Boss’s new book The Crowded Universe tells the story of the development and launch of NASA’s Kepler spacecraft, which was recently launched from the earth to go into orbit around the sun. Kepler’s 3 1/2 year mission is simple to state: find the Earths. Kepler, along with a similar ESO mission CoRoT, will be the first to finally have a chance to tell us whether planets like the one on which we live are as common as Kant would hope or as rare as some astronomers think.

Boss weaves the story of Kepler (surely a must-read cautionary tale for anyone contemplating a life in NASA mission development) with the larger story of the entire, now booming, field of exo-planets. As someone whose astronomical career has spanned the period Boss discusses, I’m glad someone was taking notes. It is fun to be able to go back to those days when each new planetary discovery was an exciting event with multiple teams struggling to outdo the others with firsts. First planet at the distance of the earth! First transiting planet! First multiple planet system! With the current richness of the exo-planet field it is easy to forget that almost all of this is under a decade old.

Boss gives the insider story not only of the Kepler mission development and the birth and childhood of the entire exo-planet field, but, in a stroke of luck for us all, he got to play a intimate role in the definition of planets in our own solar system, and he gives what I believe is the first account of some of the inner workings of the International Astronomical Union committee that first started trying to figure out what to do with Pluto and Eris and the things that we now call dwarf planets. The demotion of Pluto was unassailably reasonable, but the events leading up to this eventual demotion were some of the more publicly comical occurrences in recent astronomical history. Reliving these moments is an excellent reminder that for all of their command of the physics of the universe around them, astronomers, being human, have the capacity for nearly infinite folly.

But for Boss and The Crowded Universe, Pluto is just a distraction, and rightly so. The meat of his book is the race for finding something like the Earth. Sitting in the middle of the events, it would be easy to get caught up in the day-to-day (or perhaps committee meeting to committee meeting) details. But Boss, while detailing the daily work of himself and other scientists involved in the field, never ceases to forget that we’re privileged to live in such at a time when a nearly-Copernican-magnitude revolution is unfolding.

Yet even if Kepler and CoRoT find an abundance of planets, the 250 year old Kantian revolution will not be complete. The planets that these spacecraft might find could be the precise size of the Earth and could orbit their stars at the exact distance of the Earth, but while an astronomer might be willing to call such a thing Earth-like, most people will still want to know more. Does it have liquid water? Does it have a recognizable atmosphere? And, inevitably, the only thing that really matters, could it – no: does it – support life?

The answer to these questions will take decades or more to answer. Kepler and CoRot are simply first steps along the way. In the meantime, we can perhaps take solace from Kant:

I am of the opinion that it is not particularly necessary to assert that all planets must be inhabited. However, at the same time it would be absurd to deny this claim with respect to all or even to most of them.

It took 240 years to prove him mostly right the first time. With a little bit of luck and a little bit of perseverance and, as Boss shows, a lot of the day-to-day work of astronomers around the world, the final step might come just a little bit faster.