Astronomical Constants

Quantity

Value

astronomical unit (A.U.)

149,597,870.691 kilometers

light year (ly)

9.460536207× 1012 km = 63,240 A.U.

parsec (pc)

3.08567802× 1013 km = 206,265 A.U.

sidereal year

365.2564 days

tropical year

365.2422 days

Gregorian year

365.2425 days

Earth mass

5.9736× 1024 kilograms

Sun mass

1.9891× 1030 kg = 332,980 × Earth

mean Earth radius

6371 kilometers

Sun radius

6.96265 × 105 km = 109 × Earth

Sun luminosity

3.827× 1026 watts