Astronomy

Follow Astronomy

http://www.twitter.com/

AstronomyMag

http://www.facebook.com/

AstronomyMagazine

plus.google.com/

+astronomymagazine

6 ASTRONOMY • MAY 2018

BY DAVID J. EICHER

FROM THE EDITOR

Editor David J. Eicher

Art Director LuAnn Williams Belter

EDITORIAL

Managing Editor Kathi Kube

Senior Editors Michael E. Bakich, Richard Talcott

Associate Editors Alison Klesman, Jake Parks

Copy Editors Dave Lee, Elisa R. Neckar

Editorial Assistant Amber Jorgenson

ART

Graphic Designer Kelly Katlaps

Illustrator Roen Kelly

Production Specialist Jodi Jeranek

CONTRIBUTING EDITORS

Bob Berman, Adam Block, Glenn F. Chaple, Jr., Martin George,

Tony Hallas, Phil Harrington, Korey Haynes, Jeff Hester, Liz

Kruesi, Ray Jayawardhana, Alister Ling, Steve Nadis, Stephen

James O’Meara, Tom Polakis, Martin Ratcliffe, Mike D.

Reynolds, Sheldon Reynolds, Erika Rix, Raymond Shubinski

EDITORIAL ADVISORY BOARD

Buzz Aldrin, Marcia Bartusiak, Timothy Ferris, Alex Filippenko,

Adam Frank, John S. Gallagher lll, Daniel W. E. Green, William K.

Hartmann, Paul Hodge, Edward Kolb, Stephen P. Maran, Brian

May, S. Alan Stern, James Trefil

Kalmbach Publishing Co.

CEO Dan Hickey

Senior Vice President, Sales & Marketing Daniel R. Lance

Vice President, Content Stephen C. George

Vice President, Consumer Marketing Nicole McGuire

Art and Production Manager Michael Soliday

Corporate Advertising Director Ann E. Smith

Circulation Director Liz Runyon

New Business Manager Cathy Daniels

Retention Manager Kathy Steele

Single Copy Specialist Kim Redmond

ADVERTISING DEPARTMENT

Phone (888) 558-

Advertising Sales Manager Steve Meni

Advertising Sales Representative

Dina Johnston, [email protected]

Ad Services Representative

Christa Burbank, [email protected]

RETAIL TRADE ORDERS AND INQUIRIES

Selling Astronomy magazine or products in your store:

Phone (800) 558-

Outside U.S. and Canada (262) 796-8776, ext. 818

Fax (262) 798-

Email [email protected]

Website http://www.Retailers.Kalmbach.com

CUSTOMER SALES AND SERVICE

Phone (877) 246-

Outside U.S. and Canada (813) 910-

Customer Service [email protected]

Digital [email protected]

Back Issues [email protected]

CONTACT US

Ad Sales [email protected]

Ask Astro [email protected]

Books [email protected]

Letters [email protected]

Products [email protected]

Reader Gallery [email protected]

Editorial Phone (262) 796-

Copyright © 2018 Kalmbach Publishing Co., all rights reserved. This pub-

lication may not be reproduced in any form without permission. Printed in the U.S.A. Allow 6 to 8 weeks for new subscriptions and address

changes. Subscription rate: single copy: $5.99; U.S.: 1 year (12 issues) $42.95; 2 years (24 issues) $79.95; 3 years (36 issues) $114.95. Canadian:

Add $12.00 postage per year. Canadian price includes GST, payable in U.S. funds. All other international subscriptions: Add $16.00 postage per

year, payable in U.S. funds, drawn on a U.S. bank. BN 12271 3209 RT. Not responsible for unsolicited materials.

O

ne of the most

fundamental ques-

tions we innately

have as humans is

the simple notion

of where we came from. In

astronomy, that question

can be asked on a variety

of scales — where did we as

creatures come from? Where

did our solar system come

from? Our galaxy? he uni-

verse at large?

This month’s cover story

by science journalist Jesse

Emspak takes on the ques-

tion of the origin of the solar

system. For many years,

astronomers thought they

had a neat answer, with the

Sun and its retinue of planets

having coalesced from a

dusty disk, the debris clear-

ing out once our star began

nuclear fusion. From there, it

was a simple matter of Jupiter

dominating the gas giants, by

happenstance, and Earth

taking on the role as the most

massive of the terrestrial

planets by pure luck. They

also believed that our solar

system is typical, and that

most solar systems around us

ought to resemble ours.

Studies over the past

few years have upset the

apple cart of how our solar

system formed and its early

history. Emspak’s story tells

the sordid tale as it is now

shaping up for planetary

scientists.

The idea that our solar

system’s early history must be

very different from the con-

ventional notion came along

suddenly. Fueled by com-

puter modeling and by obser-

vations made by the Kepler

space telescope, the new view

of the solar system is radical

compared with the old.

Scientists now know that

protoplanets bounced around

the early solar system “like

billiard balls,” in Emspak’s

words, and that our solar

system is very different from

most others we see around

us. The so-called Late Heavy

Bombardment pummeled the

inner solar system, and we

can still see its effects on the

ancient surfaces of Mercury

and the Moon.

Compared with the mod-

els, the real Mars in our

solar system is far less mas-

sive than astronomers would

expect it to be. Scads of

small objects like asteroids

and Kuiper Belt objects have

been scattered into eccen-

tric, oddball orbits.

Something catastrophic or

extremely energetic had to

have pushed these bodies

into their weirdo orbits, and

planetary scientists now

believe that migration of

planets played a major role

in the early history of our

solar system.

Many planetary scientists

now believe that Jupiter

formed relatively close to the

Sun and pushed outward

early on, clearing a lane and

shoving material outward,

as it also left a “tail” of

debris in its wake. Saturn

then formed, and both plan-

ets moved inward in a kind

of spirograph wobble, f ling-

ing other objects inward and

outward. After depleting

material near them, the two

largest planets made their

way outward once again.

The details of how we got

the solar system we have

today are incredible. These

are still ideas being worked

on, but they clearly show

that forming the solar sys-

tem was a far more compli-

cated task than anyone

imagined until just a few

years ago.

Yo u r s t r u l y,

David J. Eicher

Editor

How our

solar system

formed

Follow the Dave’s Universe blog:

http://www.Astronomy.com/davesuniverse

Follow Dave Eicher on Twitter: @deicherstar