“Astronomy is a challenge against darkness, and this book narrates all the times we hypothesized about new worlds hidden in the dark depths of the Solar System. Some were genuine discoveries, others were illusions, yet we always learned something new.”
—— Amedeo Balbi, Astrophysicist

★ A new book by Italian National Award for Scientific Communication-winning astrophysicist Luca Nardi, as rigorous as an academic paper yet as vivid as a cosmic epic, once again showcasing the narrative magic that makes the profound universe accessible to all.
★ This book is the first systematic exploration of the "missing planets" in the history of astronomy—from the once-firmly-believed Vulcan, to the eventually discovered Pluto, and the still-mysterious Planet Nine. With a detective-like approach, the author weaves together scientific hypotheses, observational errors, and groundbreaking discoveries into a grand tapestry of intellectual exploration. It reveals how humanity continuously pushes the boundaries of imagination in its struggle against the cosmic darkness, offering both a retrospective look at history and inspiration for future exploration.

This book explores a completely novel topic: missing planets. From Vulcan to Planet X, the discovery of new worlds captivates us and reveals how much remains unknown in our universe.

The tale of "missing planets" is one of the most fascinating epics in astronomical exploration, weaving together over three centuries of science, history, and space discovery.

Some "missing planets" were sought but never existed, like Vulcan—a small body hypothesized to orbit extremely close to the Sun, whose mystery guided Einstein toward the theory of relativity. Others were successfully found, such as the ice giant Neptune at the edge of the Solar System. Sometimes, this quest led to entirely different discoveries: a century ago, speculation about an unknown planet called "Planet X" led Clyde Tombaugh to observe and discover Pluto. But this is not just history—even today, we are still searching for a missing planet: the mysterious Planet Nine, an icy super-Earth that could lie tens of billions of kilometers away from the Sun.

This is the first book entirely dedicated to the mystery of missing planets—bizarre, strange, and sometimes… non-existent celestial objects.

Luca Nardi
Luca Nardi is an astrophysicist, planetary science Ph.D., and science communicator. Widely known across social media, particularly on his YouTube channel, he collaborates with the Planetarium of Rome and various publications, including Wired Italia. He has published Un mese a testa in giù (2021), and Giganti ghiacciati (2023)—winner of the National Prize for Scientific Dissemination.