We are The other made me such a trick question how many times the earth rotates on itself over a year? Most would say 365, then no. Well that last is true but only half, if we consider the sun. It is true that the earth turns around 366 or so. Now you will wonder why it occurs this curious detail.
To explain this phenomenon we must take into account the definition of solar day, which is the elapsed time between two steps of the sun by the same meridian. But while the earth rotates on itself, is also revolving around the sun, that means that when a land has completed a turn on its axis, the position of the meridian is diverted at an angle, so you must still turn a bit more to complete the day. If we now add these angles "surplus" we see that the sum 360 °, if a loop more. But once made this introduction, I would like to talk a bit more of a concept as day. When the first day I talk to referee a solar day, but there are several types of days you will wonder, yes. Apart from the solar day which is what we use in our daily lives in general, and the cost of 86,400 seconds, which is actually a mean solar day, because this is not regular due to fluctuations in the speed of rotation of the Earth, this is schedule used in civilian life and is denoted as UT1. There is lso apparent solar day, is what is given by the position of the sun in the sky, is related to the mean solar day by calling
equation
time.
other hand we can talk or sidereal sidereal day
, but I think the second last prevails, as the time elapsed between two successive steps of a meridian by the First Point of Aries. Its main difference from the solar time is given by the translation movement that made the earth to the sun, which we discussed earlier, when completing a full rotation on itself must move at an angle to maintain the same position on sun, but instead of taking into account the sun we take as reference a distant star this angle becomes almost zero. This means that the solar day is slightly longer than the sidereal day.
Offset between UTC and UT1 
But back a moment to mean solar time and us go back to the creation of the International Measurement System. This defined the second initially, depending on the rotation of the earth as part of a day 86,400. Later this definition was changed due to irregularities in the rotation of the Earth, mainly caused by the moon, and the second step to be 9,192,631,770 periods of radiation corresponding to the transition between the two ground state hyperfine levels of the isotope 133 of cesium atom. This new definition was the birth Two new systems of measurement of time on one hand the UTC or coordinated universal time, based on atomic clocks. Due to the high accuracy timing atomic clocks, there is little difference between UTC and solar time. If this difference is less than 0.9 seconds is considered correct, if instead exceeds that level, then adds a second, called leap second to atomic clocks all, to maintain synchrony. But he also appreciates the opportunity to discount a second even never been produced so far. These latter are traditionally added on June 30 or January 1. Although there have been proposals to abolish the leap second replaced by the hour or interlayers, although this proposal were cast down. The other system of measuring the time it came up with the atomic clocks was the International Atomic Time (TAI
) which is analogous to UTC except that it was not added or removed will leap seconds. As there is a difference today from 33 seconds of each other. This is the time used by the majority of equipment needed for handling precision such as GPS.
Web Pages Viewed:
Malaciencia
.
Sun Dial.
Wikipedia
Microsiervos
About watches.
Superstring Theory. Thanks to XKCD 
