Why are there 24 hours in a day?

Answer 1

There are not 24 hours in a day only 23 hours, 56 minutes, and 4 seconds. Because we use 24 as an arbitary figure we have to make adjustments by adding an extra "day" every four years and further adjustments every 400 years.

Answer 2

Solar and Sidereal Day
The fact that our clocks are based on the solar day and the Sun appears to drift eastward with respect to the stars (or lag behind the stars) by about 1 degree per day means that if you look closely at the positions of the stars over a period of several days, you will notice that according to our clocks, the stars rise and set 4 minutes earlier each day. Our clocks say that the day is 24 hours long, so the stars move around the Earth in 23 hours 56 minutes. This time period is called the sidereal day because it is measured with respect to the stars. This is the true rotation rate of the Earth and stays the same no matter where the Earth is in its orbit---the sidereal day = 23 hours 56 minutes on every day of the year. One month later (30 days) a given star will rise 2 hours earlier than it did before (30 days × 4 minutes/day = 120 minutes). A year later that star will rise at the same time as it did today.



Another way to look at it is that the Sun has made one full circuit of 360 degrees along the ecliptic in a year of 365.24 days (very close to 1 degree per day). The result is that between two consecutive meridian crossings of the Sun, the Earth has to turn nearly 361 degrees, not 360 degrees, in 24 hours. This makes the length of time for one solar day to be a little more than the true rotation rate of 23 hours 56 minutes with respect to the background stars.

Answer 3

I suppose that your questiion is "Why 24 and not 37 hours?"

The answer goes back to Roman times. The Romans divided the night time into three "Watches". Soon they were able to determine the length of each watch by the rotation of the stars.

When it came to the daytime, they were able to ascertain when noon time was from sundials. However they soon realized that that the time from dawn to noon (or ½ of the daytime) was the same as 1½ "watches". By doing the math they came up with the idea that easiest way to divide both the daytime and night time into equal time periods was to divide the watch into 4 equal periods. Thus the time from dawn to noon was 6 equal periods.

Hence. Dawn to noon = 6 periods of time
Noon to Dusk = 6 periods of time
Three night watches = 4 x 3 = 12 periods of time.

Thus from one noon to the next noon was 24 periods of time.

That is how we got 24 hours in a day.

Answer 4

it takes the earth 24 hours to rotate on its axis through 360 degrees, so in a 24 hour period the earth goes through each phase once, a day is born

Answer 5

Because that is how long it takes the earth to make one full rotation.

Answer 6

because that is how long it takes the earth to make a full rotation

Answer 7

WHY NOT?