`\alpha = 2.06 \times 10^5 ( \lambda / D )`

0.3777

The Resolving Power of a Telescope calculator computes the angular distance between two stars on the limit of visibility for a telescope.

INSTRUCTIONS: Choose units and enter the following:

• (λ)  Wavelength of light
• (D) Diameter of Telescope

Resolving Power (α): The calculator returns the Resolving Power in  arc seconds.  

The Math / Science

The resolving power of a telescope is the angular distance between two stars that are just barely visible through the telescope as separate images. The resolving power α in arc seconds of a telescope with diameter D in meters that is collecting light of wavelength λ in nanometers equals is given by this formula.  The formula for the resolving power of a telescope is:

     `α = 2.06 x 10^5 ( λ / D )`

where:

• α = resolving power
• λ = wavelength of light
• D = diameter of telescope

---

Astronomy Calculators

Kepler's 3rd Law           T² = (4π • R³)/(G • M) (M) Mass of the system.  (T) Period of the orbit. (R) Separation distance between the two objects. (G) Universal Gravity Constant	Flux and Magnitude Change in Magnitude from Flux Ratio Flux Ratio from Magnitudes
Small Angle Formula         α = S / D (α) Angle (D) Distance from Size and Angle (S) Size of astronomical object	Telescope formulas Resolving Power of a Telescope Magnification of a Telescope Luminosity Luminosity from Stellar Mass Luminosity from Stellar Radius and Surface Temperature
Mass formulas Mass from Luminosity Mass from Acceleration and Radius Mass from Speed and Separation Mass of extra-solar planet from mass of star, radius of star orbit and radius of exoplanet orbit Mass of extra-solar planet from mass and velocity of star and velocity of planet Black Hole Mass Calculator Black Hole Event Horizon Calculator	Other Formulas Distance from absolute and apparent magnitude Radius from Speed and Period Speed of Circular Motion Hubble Time Galaxy Recession Velocity Luminosity from Mass Hubble's Law Exoplanet Calculator  Orbital Radial Acceleration Distance to Barycenter Sakuma-Hattori Equation Astronomical Distance Calculator  Astronomical Travel Time Calculator  3D Vector Calculator Drake Equation Calculator Seager Equation Calculator Friedman Equation Calculator Lagrange Points L1 and L2 Schwarzschild Radius Hill Sphere Radius Escape Velocity Barycenter Distance
Relative Size Formulas Relative Size from Relative Temperature and Luminosity Relative Temperature from Relative Size and Luminosity Relative Luminosity from Relative Temperature and Size
Wavelength Formulas Velocity from shift in Wavelength and Unshifted Wavelength Wavelength Shift from Wavelength and Speed Blackbody Wavelength from Temperature Blackbody Temperature from Peak Wavelength Photon Energy from Wavelength Photon Wavelength from Energy Redshift Galaxy Recession Velocity