Telescopes Resolution Degree to which fine detail can

Telescopes • Resolution - Degree to which fine detail can be distinguished • Fundamentally an issue of distinguishing angles

Telescopes • Resolution Power - Angle betwn two stars that can just be resolved • Images created by telescope have a size in at the focus that depends on the size of the objective lens or mirror Eye (5 mm) Small Telescope (5 cm) “Large” Telescope (15 cm)

Telescopes • Resolution Power - Angle betwn two stars that can just be resolved Wavelength (cm) a Small Telescope (5 cm) Resolution (arcseconds) “Diffraction Limit” Diameter of Objective (cm)

Telescopes • Atmospheric Seeing - blurring due to atmospheric motions - true limit of ground-based observations

Telescopes • Atmospheric Seeing - blurring due to atmospheric motions - true limit of ground-based observations 1 arcsec

Telescopes • Atmospheric Seeing - blurring due to atmospheric motions - true limit of ground-based resolution

Telescopes • Atmospheric Seeing - blurring due to atmospheric motions - true limit of ground-based observations Palomar Hubble Space Telescope

Telescopes • Resolution Power - Angle betwn two stars that can just be resolved Wavelength (cm) a Small Telescope (5 cm) Resolution (arcseconds) “Diffraction Limit” Diameter of Objective (cm)

Telescopes • Atmospheric Seeing - blurring due to atmospheric motions - true limit of ground-based observations