Moon Phase Finder
Estimate the moon phase and illumination for any calendar date.
Astronomy & Space5 indexed toolsClient-side first
Astronomy & Space tools
Compare optics, sky-view calculations, and observational planning data in the browser.
Escape Velocity Calculator
Calculate escape velocity from planetary mass and radius estimates.
Planet Weight Calculator
Compare your Earth weight against gravity on planets and the moon.
Telescope Magnification Comparator
Compare eyepiece magnification and field-of-view tradeoffs for one telescope setup.
Telescope Field of View Calculator
Estimate telescope magnification, true field of view, and exit pupil using aperture, focal length, and eyepiece data. It helps astronomy hobbyists compare setups before a night of observing.