Tuesday, April 18, 2017

Author Event: Exoplanets!

Exoplanets: Diamond Worlds, Super Earths, Pulsar Planets, and the New Search for Life Beyond Our Solar System,
by Michael Summers and James Trefil.

On Thursday night at 7:00 p.m. at the Buena Vista Branch, Michael Summers will discuss his new book, Exoplanets, co-written with James Trevil, his colleague at George Mason University. This book is about the major discoveries of exoplanets (planets outside of our own solar system) during the last 10 years, discoveries that have caused us to change some of our most important assumptions about the universe. The new planets reviewed in Exoplanets are a sampling of the various types (more than 2000!) found by the Kepler space telescope since the launch of that satellite in 2009. The important thing to note about the Kepler satellite is that it is focused directly on only a single pencil-thin slice of our galaxy, so the discoveries made to date give us some idea of the vast number of planets in the universe.

Ice worlds may be one of the most common
types of planets in our galaxy. We have at least
six examples in our solar system: the moon
Europa, seen here, may have biological
significance. Its subsurface ocean is heated
by internal tidal dissipation due to gravitational
interactions with Jupiter and Io, and may have
hydrothermal vents and other similarities
to Earth’s deep-ocean regions.
A primary interest of astronomers monitoring the Kepler discoveries is identifying which of these planets are located around their stars in areas called CHZ (continuously habitable zones) and have the conditions to support life as we know it here on Earth. These are the so-called “Goldilocks” planets, after the eponymously named story, places that are neither too hot nor too cold, but just right for life to flourish. Perhaps the most astonishing thing revealed by these discoveries, however, is that--much like the discovery of dark matter and dark energy in the universe--it appears that most of the planets in the galaxy are not, as we had assumed from the model of our own solar system, star-centric. They have been dubbed “rogue planets,” planets wandering through space rather than orbiting a star. The work of Kepler is being supple-mented by that of other space satellites. Some readers may recall that in February of this year NASA announced a major new discovery by its Spitzer infrared telescope of additional earth-like planets orbiting the “ultra-cool dwarf star,” TRAPPIST 1.

Exoplanets come in a wide range of masses, compositions, temperatures,
densities, and distances from their central star. There is a continuous
spectrum of masses, from planets the size of Mercury to thosemore than
10 times the mass of Jupiter. They can be as hot as metal or
as profoundly cold as interstellar space.
Exoplanets is a popular work of science, one intended to bring lay readers up to date on significant new discoveries about the universe, and the implications of those discoveries. An outstanding work of popular science does several things: It explains scientific concepts clearly, often by use of analogies to more commonly understood phenomena; it does so while presenting a logical and concise overview of its subject;
it explains what we have come to know, or think we know, and why and how we think we know it; and, last but not least, it points out what we do not know and directs us to the important things we need to know.

That last point is critical in the lasting impression a book like this will have for us, and in fact integral to its purpose, for what is attractive to us are the mysteries yet to be uncovered, our anticipation--and our speculation--about what the answers might be. It is the thing that we find stimulating and expansive in a book like this, as it engages our imagination and makes the world a larger, more complex, and seemingly boundless place. This book does all of those things superbly, and Jim Trefil’s long experience and deft hand as a popular science writer is apparent here. And of course, the subject of a book of popular science has a lot to do with how engaging we find the book, and what could be more engaging than a book that addresses a subject that causes us to speculate broadly on the working of the universe, the origins and nature of life, and our place in the whole thing?

Most stars have planets--in fact, observations suggest that on average each star
has at least four.  This estimate is derived by extrapolating the frequency of exo-
planets that we have observed around stars other than our Sun.  Furthermore,
research suggests that most planets are not even bound to stars. 

This is a small jewel of a book, and it has many facets. You are presented with a wealth of intriguing ideas as you are ushered back and forth between speculative worlds and across eons of time. But this is not science fiction, it is a combination of fact and informed speculation, and it is all the more powerful for that. Perhaps each reader will find something that particularly strikes them.

A student from the Burbank High School astronomy club will give a short introduction. The Sidewalk Astronomers will be on hand with telescopes that are popular with amateur astronomers, should you want to take your interest to the next level. Books will be available at a special price for those who attend, and the author will sign copies. Proof of attendance will be provided for students who are attending for extra credit. It promises to be a fascinating and fun evening!

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