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When is a star going to pass by? Choose any of 493 named stars, a place and a date — and see when it rises, when it crosses your meridian at its highest, and when it sets.
Latitude north / longitude east are positive. With custom coordinates, times use your chosen UTC offset.
A star's daily path is fixed by two numbers in the catalog: its right ascension (its longitude on the celestial sphere) and its declination (its latitude there). The Earth's rotation, measured against the stars as sidereal time, carries the star across your sky at 15.04° per hour. It transits — passes highest, due south or north of you — when sidereal time equals its right ascension; rise and set follow from the hour-angle formula with the star 0.58° below the horizon (allowing for atmospheric refraction). Catalog positions are from the Yale Bright Star Catalog.
Worked example: Sirius, the brightest star, from New York on New Year's Eve (December 31, 2026): it rises in the early evening and passes highest almost exactly at midnight — the sky's own New Year marker, as it has been since ancient Egypt timed the Nile flood by this star. Set the star to Sirius, the place to New York and the date to 2026-12-31 above, and read the transit line.
The moment a star crosses your meridian — the great circle running from north to south over your head. It is then at its highest point of the day, and usually best placed for viewing.
The Earth orbits while it spins, so the stars gain roughly 3 minutes 56 seconds on the sun each day. Over a month that is two hours — which is why the evening sky changes with the seasons.
Daylight. A star above the horizon in daytime is washed out by the sun; use the Sunrise & Sunset page to see when darkness falls, and pick a date when the star's hours up fall in the night.
Stars near the celestial poles. From New York, Polaris and its neighbors are circumpolar — they circle the pole and never set — while far-southern stars like Canopus never clear a northern horizon at all. The calculator tells you which case applies.