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Convert Day (d) to Hour (Sidereal) (h (sidereal)) instantly.

About these units

Day (d)

A day represents a full rotation of the Earth relative to the Sun, traditionally measured as 24 hours. Although the day is deeply tied to astronomy, its exact length varies due to Earth's gravitational interactions with the Moon, tidal braking, and geophysical processes. The modern civil day uses Coordinated Universal Time (UTC), with occasional leap seconds added to compensate for subtle variations in Earth's rotation. This ensures that civil time remains aligned with the real solar day. Days are fundamental in cultural, religious, biological, and economic cycles. Sleep patterns, work-rest rhythms, calendars, and circadian biology all operate on daily cycles, making the day not just a unit of measurement but a cornerstone of human existence.

Hour (Sidereal) (h (sidereal))

A sidereal hour is 1/24 of a sidereal day, approximately 59 minutes and 50.17 seconds of solar time. Astronomers use sidereal hours to measure right ascension and to coordinate telescope pointing systems. Because stars return to the same apparent position after exactly one sidereal day, sidereal hours offer a stable celestial reference frame. While not used in daily life, sidereal hours are indispensable for precision observation of the universe.

More Day converters

Day [d] ↔ Second [s]
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Day [d] ↔ Minute [min]
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Day [d] ↔ Hour [h]
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Day [d] ↔ Week [week]
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Day [d] ↔ Month [month]
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Day [d] ↔ Year [y]
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Day [d] ↔ Millisecond [ms]
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Day [d] ↔ Microsecond [µs]
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Day [d] ↔ Nanosecond [ns]
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Day [d] ↔ Picosecond [ps]
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Day [d] ↔ Femtosecond [fs]
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Day [d] ↔ Attosecond [as]
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Day [d] ↔ Decade [decade]
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Day [d] ↔ Century [century]
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Day [d] ↔ Millennium [millennium]
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Day [d] ↔ Shake [shake]
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Day [d] ↔ Planck Time [tₚ]
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Day [d] ↔ Month (Synodic) [month (synodic)]
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Day [d] ↔ Year (Julian) [y (Julian)]
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Day [d] ↔ Year (Leap) [y (leap)]
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Day [d] ↔ Year (Tropical) [y (tropical)]
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Day [d] ↔ Year (Sidereal) [y (sidereal)]
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Day [d] ↔ Day (Sidereal) [d (sidereal)]
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Day [d] ↔ Hour (Sidereal) [h (sidereal)]
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Day [d] ↔ Minute (Sidereal) [min (sidereal)]
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Day [d] ↔ Second (Sidereal) [s (sidereal)]
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Day [d] ↔ Fortnight [fortnight]
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Day [d] ↔ Septennial [7 years]
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Day [d] ↔ Octennial [8 years]
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Day [d] ↔ Novennial [9 years]
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Day [d] ↔ Quinquennial [5 years]
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Day [d] ↔ Quindecennial [15 years]
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Convert Day to Hour (Sidereal)