Leap second

Description

The rotation of the earth around its axis defines our natural measure of time, the length of the day. If you divide the average tag length over a year by 86400 (24 hours * 60 minutes * 60 seconds) you get to the so-called world time second. This was the unity of the “world time” until 1956, which is called by astronomers UT 1 (of Universal Time 1). On the other hand, it was recognised that the rotation of the earth is quite uneven and that, especially in the long-term mean, the rotation speed decreases, so the day length increases. One reason for this is the influence of low tide and tidal friction. This temporal change in the Earth’s rotation is the cause of the fact that, on average, over the last 40 years, the world-time second was 16.6 billionths of a second longer than the atomic second, as defined in 1967. The insertion of switching seconds as compensation does not take place in a fixed rhythm, but on the basis of observations of the Earth’s rotation, with reference to the reference system of quasars, with reference to the satellites of the GPS navigation system unharmed by the fluctuations of the Earth’s rotation and with reference to other satellites that orbit the Earth for special scientific purposes. These observations are collected and evaluated by the IERS (International Earth Rotation and Reference Systems Service). Normally leap seconds are inserted at the end or in the middle of a year, to the last minute of 30 June and 31 June respectively. On December 12, the UTC (Coordinated Universal Time) clock scale. This corresponds to the last minute of the second hour of 1 July in CEST or the first hour of 1 January in CET. On 01.01.1972, the starting point of the UTC scale, the difference TAI-UTC was set to 10 seconds. The first leap second was introduced in mid-1972.

Resources

Name Format Description Link
8 http://u99132.bs.ptb.de/cms/fileadmin/internet/fachabteilungen/abteilung_4/4.4_zeit_und_frequenz/pdf/2015_Schaltsekunden.csv

Tags

  • ptb
  • atomzeit
  • koordinierte-weltszeit
  • schaltsekunden
  • erdrotation
  • physikalisch-technische-bundesanstalt

Topics

  • EDUC
  • TECH

Categories