American Scientist

TARGET EARTH: Meteorites, Asteroids, Comets, and Other Cosmic Intruders That Threaten Our Planet. Govert Schilling, translated by Marilyn Hedges. 120 pp. The MIT Press, 2025. $21.95.

Imagine a calm Arizona high-desert landscape—the San Francisco Peaks in the distant background, animals milling about. Suddenly, an explosion on the scale of an atomic bomb occurs, wiping out all life for tens of miles and leaving behind a mile-wide crater. That can happen when a meteorite hits the Earth, as occurred at Meteor Crater, approximately 35 miles east of Flagstaff, Arizona, about 50,000 years ago.

In Target Earth: Meteorites, Asteroids, Comets, and Other Cosmic Intruders That Threaten Our Planet, author Govert Schilling provides a compelling exploration of our vulnerability to cosmic impacts. Translated by Marilyn Hedges, this accessible book arrives at a time when public interest in near-Earth objects (NEOs) continues to grow. Schilling's work stands out for its conversational tone and wealth of fascinating details—for example, did you know that rovers have discovered fifteen meteorites on Mars since 2005? By placing recent events like the 2013 Chelyabinsk impact in broader scientific contexts, Schilling creates a narrative that feels both urgent and relatable, which is bound to help readers understand the genuine cosmic threats orbiting silently above us.

Target Earth follows a thoughtful progression, beginning with personal and historical encounters with meteorite impacts. Schilling opens with his childhood memory of seeing a photograph of Ann Hodge, displaying the wound she received from being struck by a meteorite—an image "forever etched in my memory," he writes. From these human-scale incidents, the narrative expands to explain asteroid distribution throughout the Solar System, how asteroids have collided with other planets, moons, and even each other, and the role asteroids play in major extinction events such as the one that eliminated the dinosaurs. The latter portions of the book focus on humanity's current situation: how close we've come to catastrophic impacts, our ongoing vulnerability to them, and the detection and mitigation systems we have developed to respond to potential impacts. The book concludes with an intriguing look at the potential for asteroid mining.

Schilling, an award-winning Dutch astronomy writer whose bylines can be found in magazines such as Sky & Telescope and Science, excels at making complex astronomical concepts digestible. His writing style is particularly effective when explaining the real impact that science can have on everyday life, as he does when describing the aftermath of the dinosaur-killing asteroid: "For at least 10 years, the Sun was obscured by large amounts of dust in the atmosphere. The average temperature on Earth plummeted at least 40 degrees Fahrenheit. Photosynthesis came to a virtual standstill, food chains were broken, and eventually almost all life on Earth gave up the ghost."

The book also contextualizes planetary defense within broader current events. When discussing the 2004 discovery of the 340-meter asteroid Apophis, which initially showed a 2.7 percent chance of Earth impact in 2029—an alarmingly high probability for planetary defense experts—Schilling notes how this news "was overshadowed by reports of a real natural disaster." That disaster was the 2004 earthquake and subsequent tsunami in Indonesia, India, and Thailand that resulted in over 200,000 fatalities. This juxtaposition effectively illustrates how immediate crises often overshadow potential future catastrophes.

The accessibility of Schilling's writing is what makes it shine, and he occasionally employs humor to demystify technical distinctions. He jokes about how "astronomers and geologists like there to be a box for everything" and will "correct you in no uncertain terms if you say you saw a meteorite appear in the night sky," gently reminding the reader that distinctions matter. As someone who works in planetary defense at SPACEWATCH®—one of the organizations mentioned in the book—I was particularly interested in the chapter titled "Open Season," which describes the work of tracking NEOs. 

Schilling makes planetary defense relevant and understandable to all readers by clearly communicating why this niche scientific field should matter to everyone, highlighting the behind-the-scenes work that contributes to our collective safety. However, the book occasionally contains minor inaccuracies that experts will notice—for example, SPACEWATCH® doesn't have exclusive access to a 90-inch telescope, but rather to a 72-inch telescope with part-time use of the 90-inch. Similarly, some information appears slightly outdated, such as references to the now-obsolete "Spaceguard" community term or the start date for the Vera C. Rubin Telescope, which has been repeatedly postponed. However, it’s important to note that these small errors don't undermine the book's broader value, but instead reflect how rapidly the field evolves.

Target Earth offers an engaging, informative introduction to the science of cosmic impacts and planetary defense. It's ideal for readers who are curious about asteroids that might threaten Earth and who are also curious about the systems that are in place to protect us. I would particularly recommend it to those who want to understand what planetary defense researchers actually do. Most importantly, Schilling's clear explanations help bridge the communication gap that often exists between experts in planetary defense and the general public.