Useage of Small Angle Formula
Example -- the diameter of Jupiter
- at opposition, Jupiter’s angular diameter is 48 arcsec
- closest to earth -- overhead at midnight
- distance away = 5.2 AU - 1 AU = 4.2 AU
- solve SAF for linear diameter using above data
- diameter ~ 150,000 km, therefore radius ~ 75,000 km
- cf. Earth radius 6400 km
- Jupiter is huge ~10 times our radius
- 102 = 100 times our area
- 103 = 1000 times our volume
Distance to Large Magellanic Clouds
- Supernova 1987A produced a ring of light after time t
- the radius of the ring = (speed of light) x t
- The angular radius of the ring, ?, was measured
- Solve SAF for distance using above data