Is a day really just 23 hours 56 mins and 4 secs?

Question

I first read this from a book then i asked my freind and he said he heard it before as well and that our days, weeks and years arn't quite right and thats why we have leap years.
So its not the 24 hr day then really...

Answer 1

well, a day being the time it takes for the earth to make a full rotation is this length. This is absolutely true.
The clock will still give you the accurate time for social purposes, but its out of sync with the earth by a little less than 4 minutes. Like you said, that is why there are adjustments such as leap years.

Answer 2

This is true. The leap year comes in because the world makes 365 and 1/4 rotations on its axis in a year. We do not have a 1/4 day so we add them up every 4 years. Even that is an over compensation, and every leap year that would fall in a year at the turn of a century (but not a millenium) divisible by 400, the leap day is omitted!

Answer 3

well first this has nothing to do with leap year. the 23hrs,56mins,4secs is the official length of day relative to the stars. however, it is 24 hrs relative to the sun. this is because when the earth makes a revolution, it also has moved about 1 degree in it's orbit around the sun, so the earth has to rotate a little more for the sun to be in the same position it was the previous day. in leap year, there are 365 days/year, but the official length of year is 365.2422 days. so every 4 years, an extra day is added to bring the calendar year and the tropical year into accord. but when you add a leapday every 4th year, it over compensates and so only leap century years are only leap years if they are evenly divisible by 400. this helps to bring the year into accord, but it to is still off and will have to make other modifications in the future.

Answer 4

A leap year is a year in which an extra day is added to the calendar in order to synchronize it with the seasons. Since the tropical year is 365.242190 days long, a leap year must be added roughly once every four years . In a leap year, the extra day (known as a leap day) is added at the end of February, giving it 29 instead of the usual 28 days
The sidereal day is defined to be the length of time for the vernal equinox to return to your celestial meridian.
The solar day is defined to be the length of time for the Sun to return to your celestial meridian. The two are not the same,
Because the Earth is in motion on its orbit around the Sun in the course of a day, the Earth must turn about 4 minutes longer each day (3 minutes and 56 seconds, to be exact) to bring the Sun back to the celestial meridian than to bring the vernal equinox back to the celestial meridian. Thus, the solar day is 3 minutes and 56 seconds longer than the sidereal day. It is this almost 4 minute per day discrepancy that causes the difference in sidereal and solar time, and is responsible for the fact that different constellations are everhead at a given time of day during the Summer than in the Winter. As a matter of civil convenience, the Earth is divided into various time zones. The time for many astronomical events is given in Universal Time (UT), which is (approximately) the local time for Greenwich, England---the Greenwich Mean Time or GMT.- again,The true sidereal day is the time interval between two successive instants when the true vernal equinox crosses the meridian,as an example,In 1991, one mean solar day = 1.00273790935 mean sidereal days. The mean sidereal day is 23 hours, 56 minutes, 4.09054 seconds long, about 3 minutes 55 seconds shorter than the mean solar day. In other words, the stars rise about four minutes earlier each day.

Answer 5

The sidereal day is the length of time it takes the earth to complete one rotation about it's axis. On the other hand the solar day is the time taken for the sun to return to it's highest point above the horizon on two successive days. The average time for the latter of these over the course of a solar year is 24 hours-hence the 24 hours in a day. The difference arises because during the course of a day the earth orbits the sun and has to rotate slightly further for the sun to be at it's highest point over a fixed point on the planets surface but the "fixed" stars, being so far away, appear to at the same position in the sky.

To best visualise the solar day being different consider the earth making complete rotations on it's axis over the course of 6 months and a point which at the start faces directly to the sun. after six months of complete rotations the same point now points directly away into space.

Answer 6

Leap years are due to the Earth's orbit around the sun. They have nothing to do with the Earth's rotation. Leap seconds are added occasionally to correct the fact that the Earth does not revolve on its axis in exactly 24 hours.

Answer 7

That's right.
'A leap year (or intercalary year) is a year containing an extra day (or, in case of lunisolar calendars, an extra month) in order to keep the calendar year synchronised with the astronomical or seasonal year. For example, February would have 29 days on a leap year instead of the usual 28. Seasons and astronomical events do not repeat at an exact number of days, so a calendar which had the same number of days in each year would over time drift with respect to the event it was supposed to track. By occasionally inserting (or intercalating) an additional day or month into the year, the drift can be corrected. A year which is not a leap year is called a common year. In fact, the Earth takes slightly under 365 1/4 days to revolve around the Sun.'

Answer 8

That's the duration of a sidereal day -- the time interval between which any given star crosses a particular meridian. The solar day is of course 24 hours, being the time beween successive mean solar noons (not actual noons - there is a complication called the equation of time, which arises because the earth's orbit around the sun isn't a perfect circle).

Answer 9

This has nothing to do with leap years. The extra 3 minuits are because in one day the earth has moved a bit more round the sun.

Answer 10

There are different kinds of days. A solar day is 24 hours( ffom noon to noon).. A siderial day is 4 minutes shorter( when the stars return to the same position.