If a day is <24hours, how are we still aligned with Day/night?

Question

Suppose a Day is 23 hours and 59 minutes. Every last minute, sunlight will come an avg. a minute sooner. After 90 days, we are talking 1.5 hours sooner, while night comes 1.5 hours sooner. How do we not experience this while we wait for Leap year to adjust a whole day?

Answer 1

The answer is that the earth does (by definition) take 24 hours to rotate.
But 365 rotations are not enough (by about 1/4 day) to make it all the way around the sun (a year). So every 4 years we add a day to catch up with 4 complete trips around the sun.

Answer 2

Days and years have absolutely nothing to do with each other. A year is determined by the time it takes to go around the Sun. A day is determined by the time it takes to rotate to the same sun-facing position. (A turn through 360 degrees, aka a "siderial" day is somewhat less, because we've moved part way around the sun, changing the angle. To us, the sun matters more than the constellations.) A CALENDAR year is a compromise between the year and the solar day because a fractional day makes no sense.

Suppose you start your year with the Sun at 0 degrees Earth longitude. Exactly one year later the Earth is in the same position, but the angle is wrong. The Sun has gone an extra 89 degrees West. We ignore this and restart the count when the Sun reached the zero position. But after four years, when the Sun has now overshot by about 354 degrees, we add the entire day to make a leap year, compensating for the mismatch.

Days are obvious because the Sun keeps disappearing. But you can't sense a year, outside of the seasonal changes. In fact, seasons are the only reason years matter to us. So it's important to synchronize days and years so we can make seasonal predictions. But it's a compromise.

Answer 3

It's the revolutions that determine when to have leap years. NOT the rotation of the sun (which IS what determines day and night). One REVOLUTION is an extra 1/4 day per year. the rotations are exactly 24 hours (give or take a few milliseconds. Maybe not even that much). If we did not have leap years, it would be the seasons that would get mixed up. Actually they do, slightly, as you said, while waiting for a leap year, but only very very slightly so we can't really tell a difference

Answer 4

Hi. The SOLAR day is 24 hours long. The SIDEREAL day is the length you are asking about. We do experience this by observing that the stars are in a slightly different position from night to night.

Answer 5

I believe you are confusing leap year with leap seconds. Leap year compensates for the number of days it takes to travel around the sun. Leap seconds compensate for the rotation of the earth. See http://en.wikipedia.org/wiki/Leap_second

Answer 6

the 24 hr day is based on the amount of time the earth takes to make 1 rotation, its not exactly 24hrs, its off a little and that is where the leep year comes in, the leep year puts us back on the schedule of the 24 hr time, daylight and night time is not a mesurement it is caused by the angel of the earth to the sun that dictates the amount of light or lack of light.

Answer 7

Daylight Savings time. We adjust forward or back an hour and every four years we add a day. It's worked so far... except in Indiana.