NEW TO THIS EDITION OF DISCOVERING THE ESSENTIAL UNIVERSE

Exoplanets The explosion of exoplanet discoveries has prompted us to add a chapter (Chapter 5) on this subject. This chapter directly follows the chapter on the formation of the solar system, reinforcing student understanding of how our own planetary system formed while showing how others also have formed.

Coverage of the altazimuth coordinate system helps students to visualize their position in the cosmos (Chapter 1).

Revised coverage of planet classification The categories of planets, dwarf planets, and small solar system bodies are explained and reconciled with the existing classes of objects, including planets, moons, asteroids, meteoroids, and comets. Also explained is how Pluto fits more comfortably with the dwarf planets than with the eight planets in our solar system.

Expanded coverage of the satellites of the planets in our solar system is included.

Many scientific updates are included in this edition, with new findings in many areas of physics and astronomy, including the discovery of the Higgs boson, indications of water activity on Mars, observations of fragmentation of an asteroid and rings around another one, the meeting of the Rosetta spacecraft with Comet 67P/Churyumov-Gerasimenko, the discovery of new exoplanets with interesting orbits and masses, the unusual sunspot cycle we are in, the improved parallax measurements by Gaia and by the Hubble Space Telescope, and new properties of the solar wind, among many other things.

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