The Astronomy Book

59 Galileo demonstrates his telescope to Leonardo Donato, the Doge of Venice. Like other astronomers of his time, Galileo relied ...

60 was directly related to the ratio of the focal length of the objective lens to the focal length of the eyepiece. A longer-foc ...

61 Galileo quickly published his discovery in his book Siderius Nuncius (The Starry Messenger), published on March 10, 1610. In ...

62 moons and claimed to have discovered them before Galileo. Galileo would later accuse Marius of plagiarism, but it is now gene ...

63 The challenge now was to find observations to prove that one theory was correct and the other false. The discovery of moons a ...

64 See also: Elliptical orbits 50–55 ■ Halley’s comet 74–77 I n 1639, a 20-year-old English astronomer named Jeremiah Horrocks p ...

65 See also: Galileo’s telescope 56–63 ■ The origin of the moon 186–87 ■ Huygens (Directory) 335 W orking at the Panzano Observa ...

GRAVITY EXPLAINS THE MOTIONS OF THE PLANETS GRAVITATIONAL THEORY ...

GRAVITY EXPLAINS THE MOTIONS OF THE PLANETS GRAVITATIONAL THEORY ...

68 G ravity is the name given to the force of attraction between any two masses. It is the force that attracts all objects to Ea ...

69 orbits, he did not know why the planets moved as they did. In his 1609 book Astronomia Nova, he suggested that Mars was being ...

70 system. This breakthrough intrigued Halley so much that he went on to calculate the orbits of 24 other comets, and to prove t ...

71 12 in (5.1 and 30 cm) (see above). Many have tried to refine and repeat the experiment since. This has led to a slow improvem ...

72 An example of a three-body system is the moon-Earth-sun. Newton thought about this system but the mathematical difficulties w ...

73 Gravity thus also shapes life on Earth by limiting the size of animals. The largest land animals ever were dinosaurs weighing ...

74 I DARE VENTURE TO FORETELL THAT THE COMET WILL RETURN AGAIN IN THE YEAR 1758 HALLEY’S COMET I n the 16th century and for much ...

75 See also: The Tychonic model 44–47 ■ Elliptical orbits 50–55 ■ Gravitational theory 66–73 observational data from different p ...

76 interested in discussing what force might account for the motions of planets and other celestial bodies such as comets. Newto ...

77 successive reappearances, which occurred about once every 75 to 76 years, of the same comet, which was traveling on a closed, ...

78 See also: Shifting stars 22 ■ Stellar parallax 102 ■ Rømer (Directory) 335 I n the 1720s, while seeking proof that Earth was ...