Keep time with
the universe.

Our calendar covers the four principal Moon phases, global solar and lunar eclipses, the four equinoxes and solstices, twelve tropical zodiac seasons, and retrograde/direct stations for Mercury, Venus, Mars, Jupiter, Saturn, Uranus, Neptune, and Pluto. It does not attempt to list every planetary aspect, meteor shower, or comet.

We calculate the astronomy with Astronomy Engine. Station times are found from changes in geocentric ecliptic longitude. Dates were checked against the U.S. Naval Observatory’s season tables, Moon phase tables, and NASA’s eclipse catalogs. Small differences between astronomical models are normal; allow roughly a minute for the displayed estimates.

The event happens at one instant worldwide. Your browser’s timezone changes its clock time and sometimes its date. Daylight saving time is handled for the event’s date. You can choose a different timezone above; no location permission is needed.

A local-time countdown does not determine local visibility. The calendar shows the global eclipse peak, which can differ from the peak at your location. Use the NASA map linked from the eclipse’s detail card to check where it can be seen. Never look directly at the Sun without appropriate solar protection.

Event dates come from astronomical calculations. The reflection beside each event is an original symbolic prompt, with room for your own beliefs. Tropical zodiac seasons describe astrological coordinates, not the Sun’s passage through astronomical constellations. A retrograde is apparent motion from Earth, not a physical reversal of a planet’s orbit. The illustrations help explain an event and are not observation maps. Moon-phase images use a conventional orientation; the Moon’s apparent tilt changes with your viewing location.

Seasons are named by month because the Northern and Southern Hemispheres experience opposite seasons. The March equinox, for example, begins spring in the north and autumn in the south.

Explore NASA’s guide to eclipses, Moon phases, and Earth’s tilt and seasons. Solar eclipses place the Moon between the Sun and Earth. Lunar eclipses bring the Moon into Earth’s shadow. An ordinary Moon phase comes from our changing view of its sunlit side.