Date calculators, holiday timers, solar terms, and cosmic countdowns — all running in your browser.
Countdown to any date or count days since any date. Select two dates and get the exact difference in days, hours, and minutes.
How many days until the next Gregorian New Year and Chinese Lunar New Year? See the upcoming zodiac animal.
Countdown to Christmas, Easter, Thanksgiving, Halloween, and more global holidays. Computed with precise algorithms.
Discover which Chinese solar term we are in now, and how many days until the next one. Based on Sun ecliptic longitude.
Countdown to upcoming meteor showers, solstices, equinoxes, and eclipses. Perfect for stargazing planning.
Enter your birth date and see exactly how many days, hours, and heartbeats you've lived. Fun physiological trivia.
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The Julian Day Number (JDN) is a continuous count of days since January 1, 4713 BC. Astronomers use it to simplify date arithmetic — you subtract two JDNs to get the exact number of days between any two dates, no calendar quirks to worry about.
USNO ReferenceThe 24 solar terms divide the year by the Sun's position along the ecliptic. Each term spans exactly 15° of celestial longitude. They are a lunisolar calendar system distinct from the lunar month system, used for agriculture in East Asia for over 2000 years.
WikipediaEaster Sunday is determined by the Computus — a set of rules that finds the first Sunday after the first full moon on or after the March equinox. Butcher's Algorithm (1876) computes it with pure integer arithmetic, valid for all Gregorian years.
Butcher's AlgorithmMeteor showers occur when Earth passes through debris trails left by comets. The International Meteor Organization (IMO) publishes an annual calendar of peak dates. Major showers like the Perseids and Geminids are reliable year after year.
IMO Calendar