Astronomy

23 free astronomy tools in the Calculators & Converters collection — every one runs in your browser with no signup and no uploads.

Estimate the EV of moonlight and get shutter, aperture, and ISO for moonlit scenes.

Calculate moon phase, illumination %, and lunar age for any date

Calculate civil, nautical, and astronomical twilight times for imaging

Find the compass direction the sun rises and sets for any date and location.

Calculate Dawes limit and Rayleigh limit for any telescope aperture

Calculate focal ratio, speed, and depth of focus for any scope

Calculate magnification, exit pupil, and true FOV for any eyepiece

Find the moon phase and illumination for any date.

Convert astronomical units (AU) to kilometers and back.

Convert light-years to kilometers and back.

Convert parsecs to light-years and back.

Find your telescope magnification from focal length and eyepiece.

Find exact sunrise, solar noon, and sunset times for any location and date.

Find the exact golden hour and blue hour windows for any location and date.

Find exact blue hour, golden hour and twilight times for any location and date.

Find the exact date and time of the next full moon — and the ones after it.

Magnification, exit pupil, true FOV, limiting magnitude and resolving power — all in one tool.

Rayleigh criterion, Dawes limit, Abbe limit, pixel scale and more — all in your browser.

Convert cosmic distances between light-years, parsecs, AU, km and more — with light travel time.

See the current moon phase, illumination, distance and next phase dates — instantly.

Compute cosmological distances, lookback time and recession velocity from redshift z.

Find the exact moment the sun peaks in the sky — plus sunrise, sunset and golden hour.

Compare star brightness, find absolute magnitude, and compute telescope limits.