Angular sizes -- small angle formula
Apparent, angular sizes given by
- 206,265 arcsec = 2 x 105 arcsec = 57o = 1 radian
- Moon
- 3476 km diameter, 384,000 km distant
- angular diameter ~ 2000 arcsec
- Sun
- 1.4 x 106 km diameter (4 l.s.), 150 x 106 km distant (1 AU)
- angular diameter ~ 2000 arcsec
- 0.5o = 30 arcminutes = 30 x 60 arcsec = 1800 arcsec
Very handy and powerful formula
- If angular diameter and distance known => linear diameter
- how sizes of planets and Sun determined