Abstract

The sun is a bright, low-contrast, extended object. One arcsecond corresponds to 725 km on the sun. In the solar atmosphere the density scale height and the photon mean-free-path are both ~100 km. Due to the large conductivity, the solar magnetic field has an extremely inhomogenous structure with a typical scale of 100 km or even less. In order to resolve 50 km on the sun, a telescope should have an angular resolution of 0.07 arcsec. In the visible (λ=500 nm), this would require an aperture of about 2 m.

© 1996 Optical Society of America