[...]... are in the northern sky and 48 are in the southern sky The remaining dozen lie along the ecliptic—a circle that describes the path that the sun takes in the course of a year against the background stars This apparent motion is actually due to the earth moving around the sun (We’ll revisit the term ecliptic in Chapter 11) These 12 constellations are the zodiac, familiar to many as the basis of the pseudoscience... comprehensive tour of the universe in The Complete Idiot’s Guide to Astronomy, Second Edition Readers will enjoy the historical approach, starting with the ancients, moving on to Copernicus and Galileo, and ending in the modern era with Neil Armstrong and others This book provides an excellent guide not only for first-time observers, but also for experienced amateur astronomers Astronomical techniques, the solar... sphere—which contained the stars—rotating, and not the individual stars All the stars, they noticed, moved together, their positions relative to one another remaining unchanged (That the stars “move” because of Earth’s rotation was a concept that lay far in the future.) The coordinated movement of the stars was in dramatic contrast to something else the ancient sky watchers noticed While the vast majority... Showers (or the Lyrids) 187 xi 00 1981 FM 6/11/01 9:55 AM Page xii The Complete Idiot’s Guide to Astronomy, Second Edition 13 So Close and Yet So Far: The Inner Planets 189 The Terrestrial Roster 190 Mercury: The Moon’s Twin 192 Lashed to the Sun 193 “I Can’t Breathe!” 194 Forecast for Venus: “Hot, Overcast, and Dense” 194 The Sun Sets on Venus (in the East) ... hours, the same objects will return to for measuring the east-west positheir positions in the sky approximately 24 hours tion of objects in the sky later After 24 hours, the earth has rotated through 360 degrees, so that each hour of R.A corresponds to 15 degrees on the sky If the celestial poles, the celestial equator, and declination are projections of earthly coordinates (the poles, the equator, and... jumped on the Moon and even hit a golf ball across the lunar surface, the Moon holds wonder Bathed in its silver glow, we may feel a connection with our ancestors of 10 millennia ago Like them, we see in the lunar blotches the face of the “Man in the Moon.” Neil Armstrong took this picture of fellow astronaut “Buzz” Aldrin about to join him on the surface of the Moon, July 20, 1969 (Image from arttoday.com)... in the sky and be able to “take their temperatures” simply from their colors Astro Byte “Arc to Arcturus” is a handy mnemonic often taught to astronomy students to help them easily locate the star Following the arc of the Big Dipper’s handle leads to this bright star Summer Nights Summer offers four bright stars Three of them form a distinct right triangle called the summer triangle Vega is at the. .. could also be used to guide and coordinate human activity As we will see in Chapters 2 and 3, the ancients became remarkably adept at using the heavens as a great clock and calendar The phases of the Moon The globe in the center is Earth The inner circle shows how the sunlight illuminates the Moon as it orbits Earth The outer circle shows how the Moon appears from Earth (Image from the authors’ collection)... Finally, we’ll take you into the cosmos aboard a host of manned and unmanned probes, satellites, and space-borne observatories Part 3, “A Walk Around the Block,” begins with a visit to our nearest neighbor, the moon, and then ventures out into the rest of the solar system You’ll find here a discussion of the birth and development of the solar system and a close look at the planets and their moons, as well... above the earth’s North Pole as the north celestial pole, and the point below the South Pole as the south celestial pole Just as the earth’s equator lies midway between the North and South Poles, so the celestial Star Words Declination is the angular distance (distance expressed as an angle rather than in absolute units, such as feet or miles) north or south of the celestial equator It is akin to lines . 26 Aristarchus Sets the Sun in the Middle and Us in Motion 26 Eratosthenes Sizes Up the Earth 26 00 1981 FM 6/11/01 9:55 AM Page vii viii The Complete Idiot’s Guide to Astronomy, Second Edition 3 The Unexplained. comprehensive tour of the universe in The Complete Idiot’s Guide to Astronomy, Second Edition . Readers will enjoy the historical ap- proach, starting with the ancients, moving on to Copernicus. 262 Using the Spectrum 262 00 1981 FM 6/11/01 9:55 AM Page xiii xiv The Complete Idiot’s Guide to Astronomy, Second Edition From Giants to Dwarfs: Sorting the Stars by Size 262 Making the Main