113 CERES. % 



distance from the sun is two hundred and sixty-three millions | 



of miies. Its atmosphere seems to be dense and cloudy. I 



The planet Ceres was discovered by Piazzi, at Palermo, i 



in Sicily, January 1, 1801. It is apparently surrounded by  



a dense atmosphere, and is of a ruddy appearance. Its j 



mean distance from the sun, and its revolution in its orbit is i 



nearly the same as that of Pallas. These newly discovered ^ 



planets exhibit various changes in appearance and size ; so j 



that their real magnitude has not been ascertained with cer- ; 



tainty. '*^ 



From some irregularities, observed in the motions of the "J 



old planets, some astronomers had been led to suppose, long ^ 



before the discovery of the four new planets, that a planet < 



existed between the orbits of Mars and Jupiter. Dr. Olbers, j 



before he made his last discovery, conceived that these '■ 



small celestial bodies were merely the fragments of a larger j 



planet, which had been burst asunder by some internal con- ; 



vulsion, and that several more might be discovered. With .: 



the intention, therefore, of detecting other fragments of the j 



supposed planet, he examined, thriopoowery year, the little J 



stars in certain constellations, till hi^iabours were crowned ^ 



with success by the discovery of the new planet Vesta. The t 



opinion, that these four small planets have been separated \ 



from one original planet, by some convulsion in nature, has 1 



been maintained by Dr. Brewster with much ingenuity and j 



plausibility. He supposes, moreover, that the phenomena ] 



of the meteoric stones, whicli have fallen on the earth from \ 



the atmosphere, may have been occasioned by the bursting j 



of this planet. 1 



Questions. — 1. By what is Mars distinguished from the rest of ; 

 the planets ? 2. Tn what time does Mars revolve round the sun ? 3. ', 

 At what mean distance f 4. What is the time of his diurnal rotation, i 

 and how was it discovered ? 5. What is the telescopic appearance | 

 of Mars ? 6. Proportion of light and heat ? 7. What is the appear- 

 ance of Vesta ? 8. When, where, and by whom were each of the i 

 new planets discovered ? 9. What is the distance of each from the j 

 sun .'' 10. By what is Juno distinguislied from all the other planets? < 

 11. What supposition did some astronomers make before the discoverj ' 

 of the new planets ? 12. What was the conjecture of Dr. Olbers, 

 and to what did it lead ? 13. To what does Dr. Brewster think the ; 

 phenomena of meteoric stones may be attributed .-' i 



