Astronomy— Continued 



1 calendar year (common) = 31,536,000 seconds* 



= 525,600 minutes' 

 = 8,760 hours* 

 = 365 days* 



1 calendar year (leap) = 31,622,400 seconds* 



= 527,040 minutes* 

 = 8,784 hours* 

 = 366 days* 



1 light-year " 9,460,000,000,000 kilometers 



= 5,880,000,000,000 statute miles 

 = 5,1 10,000.000,000 nautical miles 

 = 63,300 astronomical units 



^ parsec " 31,000,000,000,000 kilometers 



= 19,300,000,000,000 statute miles 

 = 16,700,000,000,000 nautical miles 

 = 206,265 astronomical units 

 = 3.26 light years 



1 astronomical unit = 149,500.000 kilometers 



= 92,900,000 statute miles 

 = 80,700,000 nautical miles 

 = mean distance, earth to sun 



Mean distance, earth to moon = 384,41 1 kilometers 



= 238,862 statute miles 

 = 207,565 nautical miles 



Mean distance, earth to sun = 149,500.000 kilometers 



= 92,900,000 statute miles 

 = 80,700,000 nautical miles 

 = 1 astronomical unit 



Sun's diameter =1 ,393,000 kilometers 



= 866,000 statute miles 

 = 752,000 nautical miles 



Sun's mass =1 ,987.000,000,000.000,000,000,000,000,000,000 



grams 

 = 2.200.000.000,000.000,000,000,000,000 short tons 

 = 2,000,000,000,000,000,000,000,000,000 long tons 



Speed of sun relative to neighboring stars = 19.6 kilometers per second 



= 12.2 statute miles per second 

 = 10.6 nautical miles per second 



Orbital speed of earth = 29.8 kilometers per second 



= 18.5 statute miles per second 

 = 16.1 nautical miles per second 



Obliquity of the ecliptic = 23°27'08."26 - 0:'4684 (f-1900), where f = the year 



(date) 

 General precession of the equinoxes = 50!'2564 + 0!'000222 (f— 1900) per year, where t = 



the year (date) 

 Precession of the equmoxes in right ascension = 46!'0850 + 0!'000279 (r-1900) per year, where t = 



the year (date ) 

 Precession of the equinoxes in declination = 20!'0468 — 0!'000085 (f— 1900) per year, where f = 



the year (date) 



Magnitude ratio = 2.512 



= 5/ 



100 



Charts 



Nautical miles per inch = reciprocal of natural scale -r 72,913.39 



Statute miles per inch = reciprocal of natural scale -r 63,360* 



Inches per nautical mile = 72.913.39 X natural scale 



Inches per statute mile = 63,360 X natural scale* 



Natural scale =1 :72.913.39 X nautical miles per inch 



= 1 :63, 360 X statute miles per inch* 



714 



