Free Online Tools

Instantly see the current moon phase, illumination percentage, and phase name for any date. Find the next full and new moon dates.

Live countdown to the next full moon with the traditional name (Wolf Moon, Harvest Moon, etc.) and exact date.

Calculate the exact distance from Earth to the Moon for any date. See if it's a Supermoon or Micromoon and the angular diameter.

Calculate precise sunrise, sunset, solar noon, and all twilight times for any location and date. Includes civil, nautical, and astronomical twilight.

Find the exact golden hour and blue hour photography windows for any location and date. Perfect for landscape and portrait photographers.

Calculate the escape velocity from any planet, moon, or star. Compare Earth, Moon, Mars, Jupiter, the Sun, and custom bodies.

Calculate the orbital period of any satellite or planet using Kepler's Third Law. Works for solar system objects and Earth satellites.

Calculate the event horizon (Schwarzschild radius) of a black hole for any mass. Visualize what happens when the Sun or Earth collapses.

Calculate magnification, exit pupil, true field of view, and limiting magnitude for your telescope and eyepiece combination.

Convert equatorial coordinates (Right Ascension, Declination) to local horizontal coordinates (Altitude, Azimuth) for any time and location.

Convert between calendar dates and Julian Date (JD) or Modified Julian Date (MJD). Essential for astronomical calculations and archival research.

Calculate Local Sidereal Time (LST) and Greenwich Mean Sidereal Time (GMST) for any location and time. Find what constellation is on your meridian.

Convert between apparent and absolute magnitude, calculate distance modulus, and compare star brightness using Pogson's law.

Calculate the current distance from Earth to all planets in the solar system for any date using Keplerian orbital mechanics.

Annual meteor shower calendar with peak dates, ZHR rates, and visibility from your location. Shows Perseids, Geminids, Leonids, and more.