Journey to the Exoplanets, by Edward Bell and Ron Miller. Scientific American/Farrar, Straus & Giroux, 2011. ($9.99: iPad exclusively.)
Reviewed by Sean Carroll
When I was your age, we didn't have any of these fancy hand-held portable ebook readers. We didn't have any such thing as extrasolar planets, either. Planets orbited the Sun, and books were printed on paper. And we liked it that way.
I'm assuming here I was about your age in 1992 or maybe earlier, because that's when the world changed forever. Sony introduced a "portable" device called the Data Discman, arguably the first hand-held ebook reader. That same year, Alex Wolszczan and Dale Frail made the first discovery of extrasolar planets, orbiting a pulsar with the romantic name of PSR 1257+12.
It's been a busy twenty years. Everyone and their dog is reading ebooks, and astronomers are discovering planets around other stars (exoplanets for short) by the bushelful -- 760 as of this writing, if we go by the Extrasolar Planets Encyclopedia. Which is why it seems perfectly appropriate that one of the first and snazziest ebooks devoted to science is Journey to the Exoplanets, written by Edward Bell and illustrated by Ron Miller.
Exoplanet research is a booming area of astronomy, with both the general public and professional scientists caught up in the amazing progress we've made in just a few short years. The first planets around a pulsar were a complete surprise -- nobody thought that the violent aftermath of a supernova explosion was the ideal environment for forming planets. But it was only a few years later, in 1995, that astronomers discovered a giant Jupiter-like planet around a Sun-like star, 51 Pegasi. By 2002 we were finding more than 25 new exoplanets every year; in 2010 there were over 100 discoveries announced. The French satellite COROT, launched in 2006, has over twenty confirmed discoveries; NASA's Kepler mission, launched in 2009, is more willing to report on "candidates," of which there are over 2,000 to date. Very recent work indicates that the average number of planets orbiting stars in the Milky way is greater than one -- for over a hundred billion planets total -- and the number of planets that are not bound to stars at all might be enormously larger. (The total mass in such objects is still much less than the mass of the stars, so these wandering planets aren't an important contributor to dark matter, but they're still pretty cool.)
Journey to the Exoplanets does a great job at conveying this excitement, using all the tricks an iPad-based app has to offer. The opening screen is set up like the cockpit of a spaceship, completely with not-always-intuitive navigational controls. Audio and video are sprinkled liberally throughout the pages, including helpful animations explaining the different methods used for detecting exoplanets. There is a three-dimensional tilting map of twenty stars in our galactic neighborhood, useful for when you're planning your next interstellar voyage. A "little scientist" section provides a collection of experiments for kids, from quite easy to be-careful-not-to-look-directly-at-the-Sun. And my personal favorite: the Planet Builder, which lets you set the distance, size, and age of your planet, as well as its type of host star. I vacillated between being impressed that they populated an entire four-dimensional parameter space, and disappointed that there weren't even more to choose from. (Don't I get to pick the composition of the atmosphere? Number of moons? Strength of magnetic field?)
A crucial design choice for JttE can be summed up in a single word: shamelessness. And I mean that in the best possible sense. The real problem with a field like exoplanet research is that, despite the amazing achievements we've made to discover them and the world-view-altering implications of their existence, we can't actually see the little buggers. In fortunate circumstances we can "photograph" an exoplanet as a single pixel on a grainy image; more often, we infer their existence indirectly, from changes in the brightness or velocity of their parent stars. Bell and Miller have chosen, I think, the right solution: in the absence of information, use your imagination, and lavishly illustrate that. A major highlight of the app is the Exoplanet Gallery, full of sumptuous and utterly fictional depictions of the landscape of various exoplanets, both known and conjectured. We can only hope that our real knowledge will eventually catch up with these fictitious but realistic illustrations.
While my reactions are mostly positive, there was one shortcoming that hit me immediately and never went away: it's not that easy to dig out a specific piece of information. This should be what electronic books are best at -- searching and categorizing what's inside. But JttE lacks a search function, and one's guesses about what lies behind any particular tab aren't always accurate. I'll confess that when I was looking for some of the statistics at the beginning of this review, it was much easier to turn to Wikipedia than the dedicated app I was holding in my hand.
In fact, the least satisfying part of this particular ebook experience was the "book" part. The animations and illustrations were as lavish as one might desire, but the actual text made of words occasionally seemed like an afterthought -- grey letters on a black background, scrunched next to beautiful pictures. It's made for dipping into randomly, not reading systematically.
Perhaps this is like criticizing the Model T for not having power steering or bucket seats. For an early entry in the ebook genre, Journey to the Exoplanets is remarkably slick and compelling. It's the kind of thing you'd be very happy to share with friends/family/kids who aren't already hooked by science. As gateways to the wonders of space are concerned, you could do a lot worse.
Sean Carroll is a theoretical physicist at Caltech who blogs at Cosmic Variance. His day job includes proposing new models of dark matter, dark energy, and the origin of the universe. His most recent book is From Eternity to Here: The Quest for the Ultimate Theory of Time