Universally Speaking, Earthlings Share a Nice Neighborhood

August 11, 2008

We don't have spacecraft to take us outside our solar system--not yet, at least. Still, astronomers thought they had a pretty good understanding of how our solar system formed and in turn, how others formed. In the last dozen years, nearly 300 exoplanets have been discovered. Are the solar systems in which they reside indeed like our own? Without knowledge or observations to the contrary, conventional knowledge said yes. Three Northwestern University researchers questioned that assumption and explored this question. What they learned is that the solar system in which the Earth orbits our sun is actually uncommon.

Edward Thommes, Soko Matsumura and Frederic Rasio were the first to develop large-scale, sophisticated computer simulations to model the formation of planetary systems from beginning to end. Because of computing limitations, earlier models provided only brief glimpses of the process. The surprising findings of their study titled, "Gas Disks to Gas Giants: Simulating the Birth of Planetary Systems," are detailed in the August 8, 2008 issue of Science magazine.

The researchers used a range of computer simulations to explore the formation of extra-solar planetary systems. They were able to show the action of a planet-forming circumstellar disk in three different starting condition scenarios at different intervals from the beginning of the universe to 500 million years of evolution. They found that our solar system represents the rare case in which big gas giants form, but do not migrate to the inner planetary system, and the orbits of all of the planets in the system are circular and stable.

"We now know that these other planetary systems don't look like the solar system at all," said Frederic A. Rasio, senior author of the Science paper, and a theoretical astrophysicist and professor of physics and astronomy in Northwestern's Weinberg College of Arts and Sciences. "We now better understand the process of planet formation and can explain the properties of the strange exoplanets we've observed. We also know that the solar system is special and understand at some level what makes it special."

The computer simulations were performed on a supercomputing cluster operated by Northwestern's Theoretical Astrophysics Group and partially funded by a Major Research Instrumentation grant from the National Science Foundation (NSF). Rasio's research group on exoplanets also is funded by a grant from the NSF Division of Astronomy.

The National Science Foundation (NSF)

---

---

	13 Planets: The Latest View of the Solar System (National Geographic Kids) by David A. Aguilar (Author) First, Pluto left. Then it came back, along with Ceres and Eris...and now Haumea and MakeMake, too! The recent actions of the International Astronomical Union have put every solar system book out of date. In response, National Geographic joins forces with David Aguilar of the Harvard Smithsonian Astronomical Observatory to revise our 2008 book—and to update young readers on the high-interest topic of space. Using simple text and spectacular photorealistic computer art by the author, this book profiles all 13 planets in their newly created categories—plus the sun, the Oort Cloud, comets, and other worlds being discovered. Back-of-the-book activities offer hands-on fun for budding astronomers.
	Solar System: A Visual Exploration of All the Planets, Moons and Other Heavenly Bodies that Orbit Our Sun by Marcus Chown (Author) Based on the latest ebook sensation developed by Theodore Gray and his company Touch Press, this beautiful print book presents a new and fascinating way to experience the wonders of the solar system Following the stunning success of both the print edition and the app of The Elements, Black Dog & Leventhal and Touch Press have teamed up again. Solar System is something completely new under the sun. Never before have the wonders of our solar system—all its planets, dwarf planets, the sun, moons, rocky Asteroid Belt, and icy Kuiper Belt—been so immediately accessible to readers of all ages. Beginning with a fascinating overview and then organized by planet, in order of its distance from the sun, Solar System takes us on a trip across time and space that includes a...
	There's No Place Like Space: All About Our Solar System (Cat in the Hat's Learning Library) by Tish Rabe (Author), Aristides Ruiz (Illustrator) Au revoir, Pluto! In this newly revised, bestselling backlist title, beginning readers and budding astronomers are launched on a wild trip to visit the now eight planets in our solar system (per the International Astronomical Union’s 2006 decision to downgrade Pluto from a planet to a dwarf planet), along with the Cat in the Hat, Thing One, Thing Two, Dick, and Sally. It’s a reading adventure that’s out of this world!
	Planets: A Solar System Stickerbook by Ellen Hasbrouck (Author), Scott McDougall (Illustrator) Take a trip through the solar system and discover what¹s really up in the sky! Packed with fascinating facts about planets, comets, asteroids and more, Planets is a galaxy of fun for young astronomers...and everybody who gazes at the night sky! Create your own universe and solar system with reusable stickers of the planets, asteroids, galaxies, and comets!
	Our Solar System (revised edition) by Seymour Simon (Author) Born almost 5 billion years ago at the edge of the Milky Way galaxy, our Solar System is a place filled with mystery and wonder. In the last fifty years, we have learned more than ever about the farthest reaches of our world. With dramatic full-color photographs and spacecraft images, Our Solar System takes young readers on a fascinating tour of the sun, the eight planets, and their moons, plus asteroids, comets, and meteoroids. Award-winning science writer Seymour Simon has teamed up with the Smithsonian Institution on this new, updated edition of his much admired book about the vast and mystifying part of the universe that we live in.
	The Solar System by Emily Bone (Author), Terry Pastor (Illustrator), Tim Haggerty (Illustrator) What is the surface of Mars like? Why does Venus glow in the dark? How do scientists explore faraway planets? In this book, you'll find out the answers and lots more fascinating facts about he Solar System.
	The Planets in Our Solar System (Let's-Read-and-Find-Out Science, Stage 2) by Franklyn M. Branley (Author), Kevin O'Malley (Illustrator) You live on Earth, so you already know a lot about it. But do you know about its place in out solar system? For instance, it's not the largest planet. If Jupiter were a hallow ball, 1,000 Earths would fit inside it. And did you know our planet Earth takes 365 days to go around the sun, while the planet Pluto takes 248 years? This simple text by Franklyn M. Branely introduces the nine planets in our solar system and is complemented by Kevin O'Malley's full-color illustrations, which incorporate some of the newest space photographs available. How hot is it on Venus? Which planet takes longest to orbit the sun? Find out the answers in this updated version of this popular text. Kevin O'Malleys often humorous illustrations depict a group of children and an astronomer as they learn all about...
	What's Out There?: A Book about Space (Reading Railroad) by Lynn Wilson (Author), Paige Billin-Frye (Illustrator) What is the sun made of? What causes night and day? Why does the moon change shape? Colorful collage illustrations and an easy-to-understand text bring planets, stars, comets, and the wondrous things out there in space right down to earth in a simple introduction to the solar system for young armchair astronauts. Full color.
	The Solar System (True Books: Space) by Howard K. Trammel (Author) This series explores Earth's solar system as well as galaxies, stars, and other objects in space. Each book reflects the latest research and will teach readers basic scientific principles that aid in understanding the workings of the universe.
	The New Solar System: Ice Worlds, Moons, and Planets Redefined by Patricia Daniels (Author), Robert Burnham (Foreword) Aimed at the popular audience by experienced astronomy author Patricia Daniels with contributions by former editor of Astronomy magazine Robert Burnham and highlighted by 160 photographs, diagrams and maps, this superb guide explores every corner of Earth’s planetary neighborhood, from the fiery sun at its center to the dark, icy realm where interstellar space begins. It’s a state-of-the-art observation of the solar system as we know it today and a knowledgeable forecast of what to expect in the future, from Pluto’s demotion to plutoid to the upcoming Moon mission, the likelihood of a manned expedition to Mars, and much more. From breathtaking full-color photographs to detailed explanatory diagrams to expert essays, fascinating sidebars, and informative fact boxes, the New...