What causes the length of the day to change?
156888
300 million years ago the day was about 22 hrs long. Earths rotation is getting slower and the days will be getting longer. This is because of the tidal forces between the earth and the moon. Earths oceans are being pulled on by the moons gravity. But as the moon moves in its orbit the oceans cant follow in a nice bulge because of the continents. So the oceans form another gravitaional centre offset from the center of the earth. This out-of sync tug is whats making the moon move farther away from the earth. The same force is slowing the earhts rotation. The moon is moving away from the earth by a couple of cms/year. How much longer the day gets each year I cant remember. It´s in the neighbourhood of nanoseconds. A leap second was acutally added to 2005.
221957
It has always seemed odd to me to have daylight savings time in the summer when the days are already naturally longer.  It is logical to me to at least try using it in the winter or not at all.
994954
Theres an extra day on the last week. Think how your birthday moves forward a day each year. Ther are actually 365 1/4 days in a year. The leap year every 4 years means this doesnt ever go out of synch too far
373015
because time is changing:\n12:30 12:31 12:32 and go on!!!
526017
The Earth's axis is tilted to make us facing closer to the sun a much longer time, getting more heat every day.  Thats why in winder the days are shorter, because we face away from the sun at a tilt.
6756
Scientists are delaying the start of 2006 by the first "leap second" in seven years, a timing tweak meant to make up for changes in the Earth's rotation.\n\nThe adjustment will be carried out by sticking an extra second into atomic clocks worldwide at the stroke of midnight Coordinated Universal Time, the widely adopted international standard, the US National Institute of Standards and Technology said this week.\n\nFor more info, visit:\nhttp://www.theage.com.au/news/world/a-year-late/2005/12/25/1135445473624.html
254919
Those would be changes that simultaneously affect time and space.  For example, if the mass of a black hole increases by swallowing a star, that would affect the curvature of space-time around the black hole.\n\nDoes that answer your question?  A few more details would help us to answer you better.
1218
nothing to do with daylight savings. Daylight savings is a human invention, not a natural phenomenon.\n\n...because leap seconds are not being added to compensate for the Earth's rotation slowing down.\n\nThe amount of time it takes for the earth to revolve around the sun is 365.2425 days.\n\nEven that is an approximation, the decimal digits can keep going on.\n\nSo initially, the calendar was divided evenly in 365 days. But about every 4 years, you'd be off 1 day. A century later, you've drifted off by a whole month!\n\nSo, leap years came into effect. Febuary has another day every 4 years. \n\nBut now you've approximated a year to 365.25 days, when in reality, its 365.2425 days.\n\nEvery century, you'll be off 1 day.\n\nSo that's where the next rule comes into play: "If the year is divisible by 4, but not by 100, its a leap year."\n\nNow we've approximated it to 365.2425, but because its always going to be an approximation, our calendar days are always slipping. All because the earth doesn't take exactly 365 days to go around the sun.\n\nThis is why leap seconds are added, and not to account for the slowdown of the earth's rotation.\n\nAs to why days are divided in exactly 24 hours, I'm not sure. But I would think the time difference is WAY less than 20 minutes, or we'd notice that soon enough, its dark at noon! :)  Time was divided a long time ago, and a simple system was sought for keeping track of it, so the minuts/hour/year thing is a nice division thats easy to do math with. The lost time, if its accounted for by leap years and such, could be easier to manage.\n\nFirst, I never said the earth is not slowing down. I said its not why leap seconds exist. And ok, I can entertain my explanation may be wrong, but that's no reason for your condescending tone, Jolly Roger. But look, your link brings me to a christian science evanglism site, where is the evidence that my answer is incorrect? \n\nYou haven't bothered to explain his original question. If leapseconds account for the slowdown of the earth's rotation, why are there leap seconds and not leap milliseconds?\n\nIf you want to append to your answer, at least try to do so while respecting the other users on this site, and not insult their intelligence.\n\nThis has piqued my curiosity, if there's anyone out there that has a source that says my explanation is incorrect, I mean an actual science website, you know, one that steers clear of religion, please let me know.
973387
The change does not take place until the next day....look at the following date and the change is complete.
690875
the days are not changing appreciably, but Congress did change daylight savings time, theoretically to save energy. You can read about the changes at the site below.
480279
because it relies to the events which can't be measured metrically anyway. Weeks follow the approximate lunar circle, there's 365 days in a year etc.\n\nalso, imagine we would divide a day into 100 hours. 1 hour would last only 14 minutes, which would be way too few and confusing. \nIf we divided a day into 10 hours, an hour would last 2 hours and 64 minutes. this would probably be too long, and we wouldn't have enough hours to properly determine a time of day...\n\nAn hour was determined as 1/4 of the time when the shadow of a pole travels a 60 degree angle or something... i THINK. I might be wrong on this, high school phisics is a LONG time ago. \nAnyway, it was old Sumerians or Babilonians who determined it like that and ever since it wasn't changed. We're too used to these units now, we can't just change them without causing a massive MESS :D
721642
Changes it from Thursday to the next morning.
471434
The same time as it was one second ago. The only reason it would change would be if the time was like 8:21:59; one second from that would be 8:22.\n :)
509348
u might have heard abt latitudes. Sun light constantly falls on earth. as earth moves different past of earth receives light and this is what we term as day and night. Latitudes help in determining times and it takes 15mins for sun to pass from one latitide to another. In other words we have time zones ever heard of green whtch time zone. This way, time is calculated with respect to sunrise and sunset. \n\nThus its all depending on how sunlight reaches in ur region..!
679596
Because an hour was defined such that there are 24 in a day.\n\nThe length of a day is getting longer though but it is still pretty damn close to 24 hours (and anyone who gives you 23 hours 56 minutes for the day length (or 24 hours 37 minutes for a Martian day) is a person who does not know what they are talking about.
972059
Temperature change depends on a number of environmental factors - flowing or still, sun exposure, reflective or absorptive bottom, wind, and primarily - size.  Unless it's a very small body (like a backyard fish pond), the thermal mass is so large that you won't see a significant intraday fluctuation, except at the surface.  Even a body as relatively small as a swimming pool doesn't change much in the span of a day.
34389
I get what you're asking. The answer is that the tidal cycle from high water to low water is a little longer than twelve hours long. Because of the earth's tilted axis (that's what causes summer and winter) the tidal cycle is not a simple sine curve and the two daily high tides are not equal in height. This cycle repeats on a 14 day period. Anyway, since the Atlantic coast is only 4 hrs different that the Pacific Coast, there are 4 short periods during each 24 hour day when the tides on the Atlantic coast will be moving the opposite direction of the tides on the Pacific Coast. \n\nTo see how this works, go look at the graph on this page title "Mixed, semi-diurnal tide" and look at any given 4 hour period. You'll see the result. \nhttp://www.esru.strath.ac.uk/EandE/Web_sites/03-04/marine/res_resourcebkd.htm