Page 322 - Third Book of Reading Lessons

READING LESSONS. 321
2. The solar system consists of the sun, thirteen primary planets, nineteen secondary planets, and an unknown number of comets. Of this system the sun is the centre. His diameter is computed to be 882,000 miles, and.his revolution on his own axis is per rmed in ab t 25 d s. He is distant om the earth about 95 millions of miles,-a distance so great, that a cannon ball, which moves about 8
miles in a minute, would be more than 22 years in
going from one to the other. The planets called primary, revolve round the sun at unequal dis­ tances, in elliptical orbits. Their names are, :Mer­ cury, Venus, the Earth, Mars, Vesta, Juno, Ceres, Pallas, Astrea, Jupiter, Saturn, Uranus, or Herschel, and Neptune. Mercury and Venus are within the earth's orbit, and are there re called i rior, or more properlJ, interior planets. The others being without the earth's orbit, are called s erior or e
terior planets.
3. :Mercury and Venus, when viewed through a
telescope, present pl1ases like those of the moon. }fercury is 3,224 miles in diameter, and revolves round the sun in 87 da ·s, at the distance of 37 mil­ lions of miles om that body. Venus is computed to be 68 millions of miles distant om the sun : she completes her revolution in 224 days and 17 hours. Both these planets, when viewed through a te scope, present phases like those .of the moon. Mercury can never be seen except immediately after sunset, or a little be re sunrise. Venus, as seen om the earth, is the most beautiful of all the planets. When she appears to the west of the sun, she rises be re him, and is called the morning star; when she appears to
the east of the sun, she rises after he is set, and is then called the evening star. When, either of these