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Modern timekeeping defines a day as the sum of 24 hours – but it's not that simple. Earth's rotation slows down over time. See the exact day length for today, yesterday, and tomorrow.


The Earth rotates about its axis exactly once, or 360 degrees, in about 23 hours and 56 minutes. This is called a sidereal day. The 24-hour day we all know and love is called a solar day. It represents a rotation of approximately 361 degrees about...


A day is defined by the scientific community as 86400 seconds (which also happens to be 24 hours). A solar day is not exactly 24 hours which is why leap seconds are added to certain days.


24 hours (exactly) The full day covering both the dark and light periods, beginning from the start of the dark period or from a point near the middle of the dark period; A full dark and light period, sometimes called a nychthemeron in English, from the Greek for night-day; or more colloquially the term 24 hours. In other languages, 24 hours is ...


You're right that a "sidereal" day is about 23 hours, 56 minutes, 4 seconds. But this is not a day in the everyday sense. A sidereal day is how long it takes the earth (on average) to make one rotation relative to the faraway stars and other galaxies in the sky.


Our system of telling time is based on the premise that every day is exactly 24 hours long — quite precisely, with no exceptions. This concept is fully ingrained into our culture, a core ...


How Long is a Day on Earth? I’m going to ask you how long a day is on Earth, and you’re going to get the haunting suspicion that this is a trap. Your instincts are right, it’s a trap!


How many EXACT hours and minutes are in a regular day? ... a day was divided into exactly 24 hours, each hour divided into 60 minutes, which were divided into 60 seconds. Now, however, with SI standards, a second is defined "neutral" of Earth; it's defined in terms of the time it takes for a certain isomptope to decay. ... How many EXACT hours ...


Calendar Calculations . The tropical year is the period of time required by the sun to pass from vernal equinox to vernal equinox. It is equal to 365 days, 5 hours, 48 minutes, and 46 seconds, or 365.2422 days. The tropical year is used to keep track of seasons, planting, and harvesting.


under 1/4 of all years 366-day "leap" years. Exercise : Design a reasonable calendar for an imaginary planet. Your calendar will consist of a pattern of 366-day "leap" years and 365-day regular years that approximates your planet's average number of days per year.