Astronomical and Calendar Time Conversion

This calculator allows you to convert between various astronomical and calendar-based time units. It supports conversions for sidereal and synodic days and years for planets like Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, and Pluto. Additionally, it handles standard time units like seconds, minutes, hours, days, weeks, and years (Julian, Gregorian, tropical, and anomalistic). This tool is ideal for astronomers, researchers, and anyone working with planetary and calendar-based time.

Atomic, Scientific Time Conversion

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enter a number you wish to convert (a positive number)
select the unit of the input value
choose the unit to convert the value into
decimal precision, the number of digits after the decimal point

Result

the converted value
conversions performed will be added to the history below the result

Note: You can easily reverse the conversion units by clicking the "Reverse" button or reset the fields by clicking the "Reset" button.

Planetary Time Units

Sidereal Day: The time a planet takes to complete one full rotation relative to distant stars. Sidereal days are used in astronomy to track planetary rotations independent of the Sun's position.
Synodic Day: The time it takes for a planet to rotate from one conjunction with the Sun to the next. Synodic days are relevant for observing solar conjunctions and phenomena like the phases of the Moon.
Sidereal Year: The time it takes a planet to complete one full orbit around the Sun relative to distant stars. It is used in astronomy to measure orbital periods and study planetary motion.
Synodic Year: The time between successive alignments of a planet with the Earth and the Sun (as seen from Earth). It is essential to study planetary positions relative to Earth and understand phenomena like retrograde motion.

Common Time Units

Seconds (s): The base unit of time in the International System of Units (SI) is the time it takes for a cesium atom to undergo a certain number of radiation cycles.
Minutes (min): A unit of time equal to 60 seconds.
Hours (hr): A unit of time equal to 60 minutes or 3,600 seconds.
Days (d): A unit of time equal to 24 hours.
Weeks (wk): A time unit equal to 7 days.

Calendar and Astronomical Years

Julian Year: A year in the Julian calendar with 365.25 days.
Used in astronomical calculations before the adoption of the Gregorian calendar.
Gregorian Year: A year in the Gregorian calendar, which has 365.2425 days, is the modern civil calendar used today.
Tropical Year: The time it takes Earth to complete one orbit around the Sun relative to the equinoxes, approximately 365.2422 days.
Sidereal Year: The time Earth takes to complete one orbit around the Sun relative to distant stars is approximately 365.256 days. Used in astronomy for precise measurements of Earth's orbit and stellar positions.
Anomalistic Year: The time Earth takes to complete one orbit relative to its closest approach to the Sun, about 365.2596 days. Used to study changes in Earth's orbit due to gravitational interactions.
Centuries (c.): 100 years.
Decades: 10 years. Common in time-related studies and historical periods.

Lunar and Synodic Time Units

Synodic Month (mo syno): The time between successive new moons is approximately 29.53 Earth days.
Sidereal Month: The time it takes the Moon to orbit Earth relative to the stars is about 27.32 days. Used to measure the Moon's position relative to celestial objects.
Draconic Month: The time between successive crossings of the Moon through the same node (where its orbit crosses the ecliptic), about 27.21 days. Important for predicting solar and lunar eclipses.
Anomalistic Month: The time between two successive perigees (when the Moon is closest to Earth) about 27.55 days. Used to study the Moon's orbit and distance variations.

Special Astronomical Units

Stellar Day (d stel): The time it takes for a star to return to the same position in the sky, very close to a sidereal day. They are used for precision in stellar observations.
Sidereal Seconds, Minutes, Hours: Units based on the sidereal day (23 hours, 56 minutes, 4.1 seconds) used in astronomical timekeeping.

These units are essential for time-related calculations, ranging from everyday measurements like hours and days to specialized astronomical terms like sidereal days and synodic months. This tool allows precise conversions between these units for various scientific and practical applications.

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