Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. Pages: 121. Chapters: Van Allen radiation belt, Hollow Earth, Precession, World, Flat Earth, Apsis, Effective Earth radius, South Atlantic Anomaly, List of artificial radiation belts, Geomagnetic storm, Asteroid impact avoidance, History of the Earth, Earth in science fiction, Spherical Earth, Future of the Earth, Rare Earth hypothesis, Geological history of Earth, Geomagnetic reversal, Gravity of Earth, Earth's rotation, Earth's location in the universe, Evolution of water on Mars and Earth, Geomagnetically induced current, Geographical distance, Earth in culture, Earth's orbit, List of Earth-crossing minor planets, Pale Blue Dot, Near-Earth supernova, The Blue Marble, Origin of water on Earth, Earthrise, Earth's energy budget, Mediocrity principle, Windows on Earth, Etymology of the word "Earth", Flag of the Earth, True polar wander, Substorm, Earth Orientation Parameters, Subsolar point, Jaramillo reversal, Darwin-Radau equation, Earth exploration, Earth religion, Geomagnetic latitude, Shape of the Earth. Excerpt: Earth (or the Earth) is the third planet from the Sun and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets. It is sometimes referred to as the World, the Blue Planet, or by its Latin name, Terra. Home to millions of species including humans, Earth is currently the only astronomical body where life is known to exist. The planet formed 4.54 billion years ago, and life appeared on its surface within one billion years. Earth's biosphere has significantly altered the atmosphere and other abiotic conditions on the planet, enabling the proliferation of aerobic organisms as well as the formation of the ozone layer which, together with Earth's magnetic field, blocks harmful solar radiation, permitting life on land. The physical properties of...