July-August 2017

Current Issue

July-August 2017

Volume: 105 Number: 4

The past decade has seen an explosion of discoveries of planets outside of our Solar System, dubbed extrasolar planets, or simply exoplanets. Many of the first exoplanets identified were large, about the size of Jupiter, and orbiting close to their parent stars. But such planets are not likely to harbor liquid water nor, therefore, life. More advanced techniques have allowed astrophysicists to locate exoplanets such as the one illustrated here, Kepler-138b, which was the first exoplanet discovered that has a mass and size smaller than Earth (planets are not shown at scale to star). Planets in what’s called the habitable zone around their stars could have liquid water on their surfaces. But as Howard A. Smith argues in “Questioning Copernican Mediocrity”, a significant number of additional factors are needed to determine whether intelligent life might exist elsewhere in the universe. (Image courtesy of SETI Institute/Danielle Futselaar and NASA.)

In This Issue

  • Astronomy
  • Biology
  • Chemistry
  • Communications
  • Engineering
  • Environment
  • Ethics
  • Evolution
  • Mathematics
  • Medicine
  • Physics
  • Policy
  • Sociology
  • Technology

Reexamining Lyell's Laws

Michael Robert Rampino


Increasing evidence points to the role of periodic catastrophes in shaping Earth's history, challenging long-standing dogmas within geology.

Questioning Copernican Mediocrity

Howard A. Smith

Astronomy Biology Evolution

Modern astrophysics can intimate our cosmic significance.

How to Tame a Fox and Build a Dog

Lee Dugatkin, Lyudmila Trut


A decades-long experiment opens up like a set of Russian nesting dolls, to reveal story after story, each embedded within the one that preceded it.

Scientists' Nightstand